You probably know that situation. You take something for granted and then somenody (often a child) ask you "Why.....?" and you run into trouble explaining (even if it is not the traditional origin of holes in cheeeeeese question).
I propose this thread for the discussion of everyday things like that.
This could be run as a competition/game with some readers trying to explain the current question while others try to poke holes into it.
For starters:
What is farther from the Earth? Sun or Moon or does it change?
How can you prove it with simple methods that a child (or pre-radar person) could understand? How could you estimate the relative distance of Sun and Moon to Earth and their actual relative sizes?
medium:
How can you show that the Earth is roughly spherical?
How can you calculate the size?
How can you show that the Earth is slightly flattened? (Pole to Pole shorter then from one point on the equator to the opposite point)
For experts:
Why is it dark at night?
Edited: to clean up title. Mero.
I thought about these questions for a while and then realised I am too stupid to answer them and gave up. I did work out that the moon must be further away as it is less bright and everybody knows that the further away a light is the less it illuminates.
Can we have some biological / nature easy questions please?
Easy questions indeed. My elder son asked me these very questions aged three. He started with the final question and my answer led him to asking the first two (try reconstructing my answer from that!!). We also had a discussion about the sun going round the v. the earth going round the sun. He grew up to be a physcist. I was a little relieved when my second son arrived and did not make such enquiries. Indeed when playing Trivial Pursuit, the question being what is 93 million miles away from the earth, his answer was Manchester (for those of you who do not realise the relationship between the North of England and London this may seem a strange answer but actually it showed a fine appreciation of British society for a four year old). He grew up to be a civil servant!!!
Paaaaaarr!!! I'm not even going to try to answer these questions. I'm still exhausted from answering them all those years ago :)
You know what's funny? I can only take a stab at the last one. lol
I homeschooled my kids for two years and had to show about day/night, the moon's orbit, etc...
I got out a globe, a small ball, and a flashlight. Turned off the lights and turned on the flashlight. Shone it on the ball with the ball being in between the light and the globe. Then moved the light around. My kids could clearly see the 'phases' of the 'moon' as I did this.
Actually come to think of it this would be a way to prove to a child that the sun is farther away than the moon as well. It proves that the moon is closer, because it goes 'dark' to 'light' due if being in betwen the sun and the earth.
the main problem for thew sun/moon question would be that it is difficult to prove that their distance from us is constant. How do we know that the moon is not sometimes behind the sun. They seem to be or roughly equal size with small variations over time (difficult to see with the sun without going blind of course).
The easiest way to show that the sun is much farther away I came up with is the solar eclipse. It is only visible as a total in a rather narrow strip bordered by strips of partail eclipse. the breadth of this strip is connected to the relative distances. If the sun were directly behind the moon (i.e. (earth -> sun)-(earth -> moon) = very small) the strip would be very wide and the farther the sun is behind the moon the narrower it would be.
All of this would of course need the assumption that distance and appartent size are inversely proportional and that celestial bodies do not change their size on a regular base.
The darkness at night is actually a very difficult question that requires a lot of cosmological models to solve (Olbers paradoxon)
I'll address the Earth size in a later post.
Quote from: Swatopluk on November 15, 2006, 03:23:59 PM
For experts:
Why is it dark at night?
Don't you know? So that one can fly up and study the Sun, and not get all sun-burny. Silly.
______________________
Seriously, the spherical-earth can be demonstrated by ships at sea.
First, it should be demonstrated that water, if no other forces are acting on it, will seek a level surface - that is, it will always assume a flat surface.
Therefore, the sea's surface can safely be assumed to be flat in relation to the Earth's surface.
If the Earth were a flat plane, then a ship sailing directly away from an observer, would appear to become smaller and smaller, until it became a tiny dot.
THIS phenomena can be demonstrated by birds in flight. Especially, if you observe birds taking off from a landed position, and they begin flying higher and higher and farther away. This keeps them in visual range longer, before they go below the horizon. But, their apparent size diminishes over distance.
Back to the ships. What is actually observed, is not that the ships appear to grow smaller, but that the ships seem to sink into the sea. They do get smaller, but long before they disappear as a dot, they "sink" below the wave-tops.
The first time this was observed, the observer may have concluded that the ship did indeed sink. However, when the same ship made a return journey, the reverse happened: the ship appeared to rise out of the sea as it's apparent size increased.
Upon questioning the sailors, the observer would have to discard the idea that the ship sank, as the experience of the sailors was that the ocean always appeared flat, and it was the LAND that "sank" into the sea. Or at least appeared to.
There are two obvious explanations for this observed situation. The sea has "dips" in it near to land masses, and the ships sailed into these dips. However close inspection of smaller bodies of water, such as lakes or ponds, no dips are ever observed. Moreover, these dips cannot be recreated by manipulating the bottom of the container, either.
That leaves the other obvious explanation: the actual Earth itself is curved, and the water clings to it's surface by the same forces that hold other objects down, such as people, rocks and, indeed, ships. A curved surface would neatly account for what is observed by both the land-based observer, and the sailor on the ship.
A diagram, with visual sight-lines can demonstrate how this works better than words.
that shows that the world is curved but not that it is spherical
Quote from: goat starer on November 16, 2006, 05:30:07 PM
that shows that the world is curved but not that it is spherical
True. But a sphere is much more logical than an upside-down dish, is it not?
I like topic drift. I am now considering whether spheres and/or upside-down dishes can be logical - in the sense of thinking in a logical way. My initial gut feeling is yes. Although I think it's easier to prove for an upside-down dish than a sphere. I've a feeling this proof would need to rely on some of Aggie's Hyper theories and probably needs a separate thread.
The classical proof/calculation of earth shape/size is the measurement of the angle of the sun over the horizon at noon in different places with known distances and relative positions. For a strict proof it would have to be at least 3 positions not located on a single straight line and not symmetrical to the path of the sun. That's the only simple idea I came up with to show that the curvature is different in east-west from north-south (slightly flattened sphere).
The "sinking ship" method has one disadvantage. It could be that the light has a tendency to either follow the surface or be drawn away from it, i.e. the rays of light could be curved slightly instead of being straight lines. Of course it is possible to disprove it but some effort would be needed.
Btw, all methods imply that it is possible to determine the exact direction to the center (if the earth's core would be asymmetrically positioned that could be tricky because the lead on the line would point into the wrong direction).
You see into what trouble one can run with "easy questions" ::)
If you knew we would have trouble why did you ask them. I will be sending you the bill for my councilling and psychiatry. ???
I expected to be paid the same way (despite us not being a flagellating order). My solutions to the problems probably leave a lot to desire anyway. I thought of this thread more as a discussion catalyst than a sadistic riddle game. There were e.g. a few interesting aspects in Bob's post I had not thought about and there should be an easier way to determine the curvature of the Earth than differential solar bearing.
I hope it did not look like a vanity exposition to show my superior knowledge/intellect. :oops: The "how to explain 'easy' things to children" problem is quite a real one. :smartass:
OK, time to reveal the answer that will not satisfy a 3 year old - why does it get dark at night - because the sun disappears over the horizon..... (I thought that was about as much as a 3 year old would comprehend).... well he knew what a horizon was, he wasn't bothered by that bit, just wanted to know why does that happen... that's when the trouble started
Yes it is extremely hard to explain such easy questions.
In fact there may well be a need for a handy pocket book for distressed parents.
Quote from: NoName on November 17, 2006, 08:05:11 PM
In fact there may well be a need for a handy pocket book for distressed parents.
Probably lots of them on the market but those little brats come up with new questions faster than the printing press will satisfy the demand.
Another classic (in German) is the question about the Anglo Saxons.
The German term Angelsachsen is confusing because there are already two Saxonias in Germany (Sachsen and Niedersachsen) and angeln means fishing with a rod. ::)
Here's one I've never understood. Why is it that when you leave biscuits and cake out of an airtight box the cake goes like biscuit, and the biscuit goes like cake?
They all end like biscuits in Calgary, as does ANYTHING left out (fruit in our apartment dries before it ripens).
I've been sending a couple of gallons of water through the humidifier lately (for the benefit of the houseplants), and never even get a trace of condensation forming on the windows. It is DRY here, and horrid for the skin in winter.
What's more curious is why they don't just make biscuits out of cake in the first place to avoid this.
If I was explaining the first and third to a young child, I would do it like this - assuming that they knew that the earth, sun, and moon are all round.
If the sun was a beach ball, the earth would only be a marble - that's how big the sun is. It looks smaller because it's further away, like a tree in the distance looks really little.
If the earth is a marble, then the moon is like a tiny bead, or a teeny ball of blue-tack (whichever is handier).
The earth, the marble, goes around the sun. It takes one year for the sun to go all the way round.
The moon, the bead/blue-tack, goes around the earth. It takes about a month for the moon to go all the way around.
All the time, the earth is spinning. Each time it spins is one day and one night. The day is when we're facing towards the sun, so the light can shine on it, and the night is when we're on the other side, so the rest of the earth blocks the light.
You can see that the moon is always closer than the sun.
Demonstration is the best way, in my opinion. ;D
Actually, for a 20-inch beach ball (50cm) you'd need a 1/10-inch earth - about the size of a green pea. The marble is usually about 1/2-inch, too big. Make an acceptable Uranus or Neptune. A 1-inch marble would make an acceptable Jupiter.
As for the moon, a very small pin-head would work I suppose.
Here's a cool Java site with a scale-size calculator http://www.exploratorium.edu/ronh/solar_system/
Now, if you're talking ORBITS, it gets even more interesting. Take a 1-inch marble (Sun), and the orbit of the earth would be almost 9 feet, and the diameter of the earth would only be 2 tenths of a millimeter, or about a hundredth of an inch. (remember: the average orbit of the Earth is 93 million miles)
If you keep that 20 inch sun, the Earth's orbit goes out to nearly 180 feet, or more than 1/2 of a foot-ball field (which is 300 feet). To keep it in perspective, that puts Neptune at more than a mile away, and Pluto about 1 and 1/2 miles from the 20 inch sun. (No wonder Pluto is so cold :) )
And while on the subject of scale, there is a VERY cool demonstrator of scale - it is a little animation that goes from the nucleus of an atom to an overview of the universe. I first saw this as a film in the Smithsonian museum, when I was a teenager. http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/index.html
One should not underestimate the lack of knowledge/understanding even in adults (what an elitist statement :-[). There are quite many people who cannot believe that a solar eclipse always happens at new moon. Their "common sense logic" tells them that a moon "that is not there" cannot eclipse the sun, therefore solar eclipses naturally occur only at full moon.
Concerning the cake and biscuit question
Clearly depends on the type. One thing is clear: there is a dynamic exchange between the atmosphere (gas with "dissolved" water) and the solid object. The cake could be seen as a sponge that already holds water while the biscuit is more like a dry sponge.
The atmosphere being big will have a more or less constant humidity (let's ignore the weather for a moment) while in the wrapping of the eatables there is not much air, i.e. only a fixed small amount of water. In the wrappers there will be an equilibrium between water in the eatable thing and the surroundings. In the open air a dry good will suck water from the surroundings until there is again an equilibrium. If on the other hand you have a humid good the not saturated air (unlimited capacity) will suck the water out until there is either an equilibrium or there is no accessible water left. Goods will dry often at the surface only because the water at the center cannot easily come to the outside (and the other way around in dry food, soggy on the outside but still dry inside).
That food gets soggy in the fridge is slightly different. Cold air can hold less water than hot air. The fridge permanently exchanges the air inside itself. The air from outside is cooled down and will lose some of its water content that will end either as condensation or will be sucked up by food stored in the fridge. In the oven you have the opposite effect. The hot air can hold more water and will suck it from the baking goods.
I have to admit that there are a lot of aspects concerning this that I do not completely understand. There is probably another effect of water tightly and loosely bound in the food. We will not notice it in the former case but if by some effect the tightly bound water becomes loose we will.
A nice experiment demonstrating something similar can be carried out at home too.
Get some copper sulphate. It is blue and apparently dry. Now heat it ( a gas stove would be best) and it will turn colorless/white. If you keep it under dry conditions it will stay that way but under humid conditions it will turn blue again without seemingly getting wet (at first). If you have precise scales you can show that the blue dry salt is slightly heavier than the white dry salt. In the blue version the water is bound so tightly that it cannot be detected.
There are other chemicals besides copper sulfate. Silica gel crystals behave in much the same way. You'll often find them in those "do not eat" packets that look like 1/2 size sugar packets--you'll often find these in foods that need to stay very dry. Electronics products often have them as well.
A nice source for a lot of the silica gel crystals is that new cat litter.
What many people do not realize, is that you can re-activate the crystals with heat. Get the silica gel crystals hot enough (300+ degrees F) and the water will be driven off. There is not a color change, unlike the copper sulfate.
(If one had access to a suitable oven, one could get away with purchase of only 1 bag of the kitty litter - it's pricey, when compared to clay litters - and whenever it becomes saturated, simply bake in an oven for an hour to renew. Likely you'd want enough for 2 changes - one to be baking, and one to be in use. Store the just-baked batch in an airtight container, so as to minimize absorption of atmosphere water.)
If I remember my chemistry right, the water that is bound in the copper sulphate or silica gel, is held by what is called "loosely bound". That is, it IS a chemical bond, as opposed to simply dissolved in solution or held by surface-tension as you'd see in a sponge.
This "loose" chemical bond is easily broken by the application of heat.
Isn't science fun? :O
It's called the complex binding (also very complex in detail with bonds inside the molecule weakened to allow for the outside binding to the metal that then creates a back-binding. Enough to torture chemistry students for half a year with). I chose the copper salt because of the color change. Silica gel itself has no visible change but is often dyed with cobalt salts that have a blue to pink transition.
Apart from water ammonia is a common complex ligand. A faintly blue-green copper salt solution in water will for example turn dark blue after addition of ammonia.
Next question: Why is there thunder after a lightning strikes? It's not that clouds should make sounds when crashing (otherwise we would hear it when a plane goes through the clouds). The story about the big guy with the hammer looks a bit fishy.
Air rushing into the vacuum caused by the lightning.
The charge of the strike leaves an "airless tunnel" that is refilled by the air around it, and it rumbles as it rushes into the vacuum.
If camera lenses are round, why do the pictures come out square?
Because film is a strip, not a circle, silly. And not all lenses are round.
Besides, the lens thingy is to capture the light so the imps can see to paint the picture!!
Back to the thunder. The lightning looks so thin. Why can the air filling that tiny bit of vacuum make such a deafening noise?
[That's not disputing the answer, just the counterquestion to be expected]
Additionally: An electric arc/discharge is audible with a typical "electric sound". Why doesn't the lightning sound like that?
Another tricky one: Why does the mirror switch left and right but not up and down?
----
Chatty,
But don't say "Heckuva job, Brownie!" to your camera ;D
Quote from: Swatopluk on November 20, 2006, 01:33:46 PM
Another tricky one: Why does the mirror switch left and right but not up and down?
It doesn't switch
either.
It switches front to back!
Your head is still in the same position, your right hand is still in the same position. But your image is reversed front-to-back.
Since your mind has to interpret somehow, and it 'understands' that people can turn around, but not that they can be 'reversed', then it interprets a 'reversed person as being switched from left-to-right. (The true front-to-back reversed 'doesn't make sense' because the 'turned around' is so 'obviously' the answer.)
Quote from: Swatopluk on November 17, 2006, 10:15:01 AM
The "sinking ship" method has one disadvantage. It could be that the light has a tendency to either follow the surface or be drawn away from it, i.e. the rays of light could be curved slightly instead of being straight lines. Of course it is possible to disprove it but some effort would be needed.
And to complicate things even more, radio waves
do tend to curve over water (especially salt water) to follow the surface, and they're part of the EM spectrum just like light. ::)
Another possible answer to the mirror question (Quasi-Mero is of course right, eh left, eh... whatever ;) )would be that left/right are relative to the viewer and the "person on the other side of the mirror" is falsely seen as another viewer while the other directions can be absolutely described. I have read that only the indogermanic group of languages uses that subjective perspective while others use absolute coordinates.
What would we do, if our eyes were not side by side but above each other. Would the concept of left/right still make sense (let's ignore our asymmetric inner organd for a moment).
If the tides are caused by the moon pulling why is there flood tide on the opposite side of the Earth also? And is it the moon pulling the water or does the Earth slightly change its form and the water follows the way of least resistance? [Ignore breaking/reflecting effects on coasts, that is still beyond complete mathematical modelling]
And while we are at the moon again, why do we always see the same side of it while from the moon we can see the whole earth turning in front of use once about every 24 hours?
I don't remember the tide-answer, I used to know. (old age--*sigh*)
As for the moon's face, that one I do know.
In any two-body gravitational system, each object is free to rotate on an axis within the system.
That is, as the moon circles (elipsis? it's not a true circle, actually. :D ) the earth, it also rotates about it's axis. As does the earth.
As it turns out, the axis of each is roughly in the same direction (unlike the planet Neptune, which lies on it's side).
The earth rotates once every 24 hours (roughly-- there's a tiny fraction of difference).
The moon rotates once every 28 days. As it turns out, this corresponds to a complete "lunar year" or revolution of the moon in the circular path around the earth.
Thus as the moon moves about the earth in it's orbit, it ALSO rotates at a rate that ensures the same face points to the earth.
Why this is so, is still a mystery. But there are a number of pretty theories to explain it. I'll leave the research to discover these theories as an exercise for the student. ::)
Calculation show that he tides slow down the rotation of the Earth and that one day Earth and moon would face each other with the same side permanently. To keep the angular momentum balance the moon would then be much farther from the Earth. This will actually not happen because the sun will go Red Giant long before and either swallow the Earth directly or having it tumble into it on a spiral.
What a pity for werewolves. They could either follow their inner predator by settling in the permanent full moon regions or avoid it by living somewhere else.
We'll talk about the tide effect later.
Quote from: Sibling Chatty on November 19, 2006, 05:25:39 PM
Air rushing into the vacuum caused by the lightning.
The charge of the strike leaves an "airless tunnel" that is refilled by the air around it, and it rumbles as it rushes into the vacuum.
Chatty. I would not presume to question your knowledge of the subject but I had understood that this theory had rather fallen out of favour and that it is generally accepted that lihghtning is caused by a shock wave due to thermal expansion in the plasma in the lightning channel. That is a lot harder to get accross simply.
The easiest way to explain the high tide on opposite sides of the Earth seems to be this: The force exerted is inversly proportional to the square of the distance (greater distance = lower pull).
Let's represent that with arrows of different length pointing into the same direction:
------>
---->
-->
Now let's presume that you "sit" on the middle arrow so it is not moving relative to you. How would the other arrows (representing force or velocity) look to you?
-->
.
<--
That is: If you consider yourself unmoving the other two seem to point into different (opposite) directions. With the seemingly unmoved middle you can associate the solid Earth as a whole. It is pulled towards the moon but on the side of the moon the pull is a bit stronger so everything movable on this side will "run forward". On the opposite side the pull is weaker than average, so movable objects "stay behind" because they cannot "keep up". Free-floating water will follow that. The effect is tiny but because of the great distances involved becoming visible (a few meters tide difference on a distance of 10000 km in theory). In reality the blocking landmasses can both increase and decrease the tide difference from negligible (in enclosed areas like the Mediterranean) to more than 10 m in certain other areas where different effects add.
Churches are among the buildings most often hit by lightning. Is that God's revenge for immoral priests and boring sermons?
Here's a common "easy" question.
Why is the Grass Green?
Quick answer: 'Because the Sky is Blue'.
Can anyone give any actual physical justification for the above answer? :D
The grass is green and the sky is blue to stop us walking on the sky by mistake... :P
Quote from: goat starer on November 20, 2006, 06:04:44 PM
Quote from: Sibling Chatty on November 19, 2006, 05:25:39 PM
Air rushing into the vacuum caused by the lightning.
The charge of the strike leaves an "airless tunnel" that is refilled by the air around it, and it rumbles as it rushes into the vacuum.
Chatty. I would not presume to question your knowledge of the subject but I had understood that this theory had rather fallen out of favour and that it is generally accepted that lihghtning is caused by a shock wave due to thermal expansion in the plasma in the lightning channel. That is a lot harder to get accross simply.
Goat Honey, this is science. I have NO idea if that's right or wrong. (See answer about the film and the imps. I'm as sure of that one as I am of the other...) I'm a total wash out on science and math, because my education came during a time that it was permissable to say "she's a girl, she'll never really need it" and I was stupid enough to believe it.
Swato?? Lightning sounds 'like that' when you're right by where it strikes...in the dang bar-ditch waiting for the storm to blow over. (Bar-ditch is a specific style of ditch in tornado and cattle country, made to help keep your cattle from wandering if the tornado takes the fences and gates.) Been there, done that, had the 3 days deafness.
Oh, and the churches question??
Steeples. Churches have nice tall steeples that are usually the highest thing around and that's where lightning wants to go...to the highest point. (Smart churchbuilders put a lightning rod atop the steeple and ground it securely, and by something stone or brick.)
Who made that quote about the terminal irony of churches installing lightning rods? (I always forget that).
Another church steeple effect is that the tower tends to be narrow and needle-like. A broad flat-top is less likely to be hit than a spire.
Concerning the thunder sound, that is probably a function of amplitude too. Our school van-de-Graaf generator (static electricity) made the "electric" sound. At the university a few students constructed one with condensator spheres with a diameter of about 2 m. That one didn't sizzle, it did BANG!
Quote from: Bob in a quantum-state-of-faith on November 21, 2006, 09:12:53 PM
Why is the Grass Green?
Quick answer: 'Because the Sky is Blue'.
Can anyone give any actual physical justification for the above answer? :D
there is one that goes something like this (probably not simple enough but here we go)
grass is green because it contains chlorophyll a green pigment that is able to absorb sunlight and convert it to energy (photosynthesis)
light is a specrtrum of waves with different wavelenghths. Colour perception depends on the wavelength.
In the atmosphere short wevelength light is scattered. Short wavelength light is blue and that is why the sky appears blue. look in any direction and you will see the short wavelength blue light. look directly at the sun (not recommended) and you will see longer wavelength red and yellow light.
As there is an abundance of blue light even when out of direct sunlight. there is an abundance of red light light in direct sunlight. To take advantage of this a green pigment such as chlorophyll is needed to absorb blue and red light. If it were green light that scattered in the atmosphere a different pigment that absorbed green light would be needed and the grass would be blue.
I just made that up!!! perhaps a scientist can tell me if it is complete gibberish. ;D
Chlorophyll absorbs light best in the red
Quote from: goat starer on November 22, 2006, 02:56:46 PM
Quote from: Bob in a quantum-state-of-faith on November 21, 2006, 09:12:53 PM
Why is the Grass Green?
Quick answer: 'Because the Sky is Blue'.
Can anyone give any actual physical justification for the above answer? :D
I just made that up!!! perhaps a scientist can tell me if it is complete gibberish. ;D
Chlorophyll absorbs light best in the red
I bolded your last sentence, because this is EXACTLY right!
The shorter wavelengths (blue) tend to scatter, rather than pass directly through the atmosphere, especially ultra-violet (which we can't perceive directly).
Green pigmented objects are green because they are REFLECTING green light. In this case, Blue and Yellow (the reflecting colors, red being the 3rd one in the REFLECTING spectrum. In the transmissive spectrum, the colors are Cyan, Green and Magenta-- such as you'd seen on a transparency, or on your PC monitor).
So, a plant will ABSORB the red colors, but reflect all the rest.
If it absorbed ALL the colors, it would be overloaded with energy, and get sunburn. But, by absorbing just the red, it gets sufficient energy to break apart CO2 and H2O (photosynthesis) various parts.
A simple general equation for photosynthesis is:
6 CO2 + 12 H2O + light → C6H12O6 + 6 O2 + 6 H2O
carbon dioxide + water + light energy → glucose + oxygen + waterBecause of the blue-scatter (due to absorption of light energy by free-oxygen, if I remember right), red and yellow would be the best wavelengths to absorb. red AND yellow would be too much, so yellow (and any residual blue) is reflected (making the leaves GREEN), and only the red is kept.
Thus, due to the BLUE SKY, the GRASS IS GREEN. ;D
To add another bit: Plants contain carotenoids (yellow-orange) as protectors. They absorb light in "dangerous" wavelengths and additionally capture free radicals that are a byproduct of photosynthesis. In fall the chlorophyll is degraded by the plants, so only the carotenoids remain (=> leaves turning yellow).
Actually we have to isolate chlorophyll to prove it to be green. If it were blue it could result in a color-mix: blue + yellow = green.
We do not notice it but the sun emits quite a bit in the green part of the spectrum but not enough to "overpower" the yellow impression. Interestingly there are no true green stars (at least non yet found), while about everything else can be found from blue-white to dark red.
Here's a puzzler that my Dad would ask me when I was little (partly because I'd laugh at all the homonyms, I think):
If you dig a hole, you have a whole hole. But if you fill it halfway full, you'll have half a hole, but still a whole hole. How can that be?
Quote from: Sibling Lambicus the Toluous on November 23, 2006, 02:37:12 PM
Here's a puzzler that my Dad would ask me when I was little (partly because I'd laugh at all the homonyms, I think):
If you dig a hole, you have a whole hole. But if you fill it halfway full, you'll have half a hole, but still a whole hole. How can that be?
But, wait! it gets better ;D
If you want to REMOVE something from your yard, normally, you'd dig it up.
When you dig up the hole, you're left with---an even bigger hole!
So, to REMOVE a hole, you must ADD something! Subtraction by addition? ;D
Quote from: Bob in a quantum-state-of-faith on November 23, 2006, 01:10:59 AM
So, a plant will ABSORB the red colors, but reflect all the rest.
Chlorophyll absorbs blue light best but it is very good at absorbing red light also. My explanation above explains why this is important as many plants do not get direct sunlight and must rely on scattered blue light.
here is the graph
(http://www.dlr.de/caf/technologie/technologie_transfer/technologie_transfer_caf/miniveg/x_images/Spectrum_hoch_Chl.jpg)
the hole thing works for a mound too. It works for almost enything that does not have a frixed quantity but workd particularly well for holes as they are an absence rather than a presence (which alows the second point). In anything that assumes a shape regardless of size and has the same name regardless of size subtraction and addition do not change the name.
Concerning the hole: A notorious case of an absence having a name of its own and therefore easily mistaken as "something".
Similar: cold(ness), darkness, vacuum (if you don't go into quantum mechanics/dynamics).
Additionally it is an indivisible. i.e. any part being essentially being the same as a whole (the difference between extensive [size-dependent, e.g. mass] and intensive [unchanged by division, e.g. temperature] characteristics).
----
Can a photon see itself in a mirror in front of it?
For Sibling Chatty .... (non-sciencey) What are the top five fibs parents tell their children? (no googling!!).
You were planned, It won't hurt a bit, Not until we were married, Of course Mum/Dad loves grandparent on opposite side of family, You can be anything you want to be if you work hard enough.
Quote from: Sibling Chatty on November 25, 2006, 03:17:51 AM
You were planned, It won't hurt a bit, Not until we were married, Of course Mum/Dad loves grandparent on opposite side of family, You can be anything you want to be if you work hard enough.
Don't forget the #1: Mommy & daddy still love you, of COURSE it's not your fault we are separating ...
AH, I never went through that one. Mom and Dad stayed together because of the kids. The court fight over which one would have to take us would have lasted for a decade.
So far, scores zero !! It's fibs we are after not lies ! :)
Tooth Fairy, Santa/Father Christmas, Easter Bunny, Veruca Gnome? and The Government Knows What It's Doing.
Quote from: NoName on November 26, 2006, 01:34:23 AM
So far, scores zero !! It's fibs we are after not lies ! :)
Oh!
I don't have the slightest idea WHAT the difference between a "fib" and a "lie" is, sorry! * ;D
I suppose I'm too literal-minded for most things ... :P
________________________
* I grin, because it's true: I really don't. Not to disparage on what you're asking, it's ME that's screwed up... ;)
Possibly just a matter of size.
Another of those "easy" questions: Do fish sleep?
a tricky one as it relies on a definition of sleep. Fish do nothing for periods which seems to equate in effect to sleep / rest but does not have the same brain state as sleep.
so I guess fish do not sleep (which means you cannot 'sleep with the fishes') but do chill out in a way that has sleep like effects. The difference between resting to regain energy and sleeping is pretty analagous
Quote from: Swatopluk on November 27, 2006, 12:57:34 PM
Possibly just a matter of size.
Another of those "easy" questions: Do fish sleep?
As Goat said, depends on "sleep".
I used to keep fish in aquariums of various sizes. One of the more interesting aspects, is some of the nocturnal bottom-fish I had. Many times, I'd get up in the wee-hours of the night, to see the activity of these critters.
And, I observed, the 'day' fish in a very low state of activity-- barely moving, etc. First time I saw that I thought some of 'em had died, and not "floated" yet. :D
But, based on this observation, I would say, "yes" fish sleep--- in a fishy sort of way. Since their brains are so much less complex than that of mammals, so too, their sleep is far less complex.
Why is it colder on the top of a high mountain than on sea level (ignoring the wind)?
With the Earth flatter on the poles and thicker at the equator, why doesn't all the water flow "downhill" to the poles?
How does a mole find its way and prey?
Do migrating birds sleep in-flight?
Same question for the wandering albatross
Penguins can be found up the the equator on the southern hemisphere. Why don't they cross it towards the north?
Quote from: Swatopluk on November 27, 2006, 03:44:19 PM
How does a mole find its way and prey?
A combination of smell, touch, and electrical field sensors (like Platypuses and sawfish).
I know the penguin one.
They don't want to have to explain that they can't get their ear pierced, because they don't have 'regular' ears.
(Old sailor's tradition.)
Quote from: Sibling Chatty on November 27, 2006, 07:26:47 PM
I know the penguin one.
They don't want to have to explain that they can't get their ear pierced, because they don't have 'regular' ears.
(Old sailor's tradition.)
No, it's that there USED to be penguins north of the equator, in the arctic in fact. But they were all eaten by polar bears.
It was a lesson the southern cousins never forgot ... ;D
(I'm kidding .. I really have zero idea.. ::) )
Personally, I think we're to be lauded for adding a new...perspective to scientific inquiry. ;D ;D :mrgreen: :mrgreen: ;D ;D
After all, not EVERYTHING has to make sense!!
Quote from: Swatopluk on November 27, 2006, 03:44:19 PM
Why is it colder on the top of a high mountain than on sea level (ignoring the wind)?
Now, digging down deep into my met classes back when I was a young man...
Generally speaking the lower part of the atmosphere cools with altitude at what is called the adiabatic cooling rate which is a direct application of Boyle's Law. BTW, I think, if I remember correctly, that this is about 5
oC per thousand feet. In other words if you take a sample of air at sea level and raise it up to the altitude of the top of your mountain, the reduction in temperature caused by the expansion of the gas (lower pressure due to there being less air above you "pressing" down under the force of gravity) will reflect that observed at the mountain top. Obviously there are a whole lot of local effects that determine what the actual temperature is on any given day, but overall, when averaged out, this is how the atmosphere behaves - at least in the lower part, the troposphere. Once you get up into the stratosphere, however, the temperature stays the same at around (from memory) minus 60
oC until you begin to reach the upper atmosphere then all bets are off and other, mainly kinetic effects take over and "temperature" is a bit of an academic point, for although the temperature can be very high, there is very little heat in it up there, what with there being so little air around to hold it.
Quote
With the Earth flatter on the poles and thicker at the equator, why doesn't all the water flow "downhill" to the poles?
Because the water is effected by the same force that causes the Earth to be flattened at the poles and the local water surface remains perpendicular to the sum of the two forces, gravity and cetrifugal "force". Thus there is no "downhill" to flow down. In a way, this is the same as what happens when you fill a bucket with water and swing it over your head. Even though gravity is still pulling it down, the centrifugal "force" keeps it in the bucket, as it does all the way around. If you could conduct this experiment smoothly enough, you would see the water surface tilting from side to side in your bucket, twice for each revolution as the two vectors change relative direction.
Quote
How does a mole find its way and prey?
He buys a street directory, just like everyone else. Churches are marked so he can find somewhere to pray. ;)
Sibling Bluenose
The earth explanation would fall a bit flat, if the Earth would not spin (no centrifugal force). I think one would have to calculate the potential energy level everywhere on the surface. Any local difference would create a flow towards the lower level.
Extreme case: what would happen with water on a nonspinning disk?
My guess is that it would give an elevated level at the center and a decreased level at the edges (something like 1/(x²+1) [general form, not specific solution]).
How would water distribute on a toroid planet (bagel form)? (either spinning or not spinning).
Quote from: Swatopluk on November 28, 2006, 12:12:36 PM
The earth explanation would fall a bit flat, if the Earth would not spin (no centrifugal force). I think one would have to calculate the potential energy level everywhere on the surface. Any local difference would create a flow towards the lower level.
Extreme case: what would happen with water on a nonspinning disk?
My guess is that it would give an elevated level at the center and a decreased level at the edges (something like 1/(x²+1) [general form, not specific solution]).
How would water distribute on a toroid planet (bagel form)? (either spinning or not spinning).
The SciFi author Hal Clement wrote about a fictional planet that had some interesting traits.
It was a very, very large, but very low density planet. It had a rate of spin that was sufficiently high, that gravity was noticeably higher at the poles, than at the equator. Obviously, the planet was not a regular sphere, but flattened, by the high-speed spin.
(I don't remember the title-- "Mission of Gravity" maybe? )
Mr Clement did pretty good hard science-fiction, but he did not consider the planetary stresses induced from such high-speed spinning. I would think that the planet's crust would be under constant "earthquake" conditions-- and likely not all that solidified, either. Tidal frictional heating is not something to be dismissed lightly. :)
Anyway, wanted to add that into the mix: very large planet, very low density, very high-speed rotation. Assuming the planet was large enough to have 8 times "earth" gravity at either pole, and the density was roughly 1/2 that of Earth. What would the size be? And what rotational speed would you need to achieve 1 "earth" gravity at the equator?
I remember that was roughly what Mr Clement had worked out in the story -- but it may have been 3 "earth" gravities at the equator, rather than one. (Big difference, I know ;D )
Anyway, how would water behave under such planetary conditions? (Assuming that water was liquid at the planet's surface... <heh>)
Quote from: NoName on November 17, 2006, 08:05:11 PM
there may well be a need for a handy pocket book for distressed parents.
Why don't penguins feet freeze? (http://www.amazon.co.uk/Why-Dont-Penguins-Feet-Freeze/dp/1861978766/sr=8-1/qid=1164764912/ref=pd_ka_1/203-3881032-8245560?ie=UTF8&s=books)
Quote from: Sibling Chatty on November 26, 2006, 05:08:14 PM
Tooth Fairy, Santa/Father Christmas, Easter Bunny, Veruca Gnome? and The Government Knows What It's Doing.
First two correct..but in reverse order. Easter Bunny is no. 6 but I only asked for five !!
Quote from: Sibling Chatty on November 28, 2006, 01:48:11 AM
Personally, I think we're to be lauded for adding a new...perspective to scientific inquiry. ;D ;D :mrgreen: :mrgreen: ;D ;D
We should have an Ig Nobel Monastery Prize.
Well, if it's Southern Moms and Grannies, the others are
"If you keep makin' that face, a cold wind's gonna freeze it that way."
"Eat the crusts off that bread, 'cause it'll make your hair curly."
And the ever popular "Eat your carrots so you can see good at night like bunnies can."
Or "If you keep sickin' your arm out that car window, a truck will knock it off." " Don't do _____, you'll put you eye out." And "If you don't eat your vegetables, your chest isn't ever gonna develop." (The last one for daughters.)
What I wanna know are where are the one-eyed, one armed people with frozen faces, stright hair and no boobs that can't see worth a damn??
Quote from: Sibling Chatty on November 29, 2006, 05:42:06 AM
What I wanna know are where are the one-eyed, one armed people with frozen faces, stright hair and no boobs that can't see worth a damn??
They all live and work in Washington, DC ;D ;D
Ok you got them all. Easy. I guess your last comment is why they are fibs not lies. No, that doesn't add up does it? So what is the difference between a fib and a lie?
The difference between a fib and a lie may very well be the difference between a slut and a whore...such an advanced capability that one is considered a professional.
OMG, did I just say that?? I guess I did.
Like politicians. They don't tell fibs, they lie. Professional level. :mrgreen: :mrgreen: :mrgreen:
Intriguing. One of my dearest sons called me a slut for not washing the dishes, after eating, when he saw them piled up in the kitchen. I shall now regard that as a compliment ;D after all I am much too poorly to be an effective whore.
The professional angle, well yes, it seems even politicians (well, some of them, here at least) are beginning to realise their most resounding feature is lying.
But how would one explain it to a child? Is Santa a fib not a lie because it is so obviously untrue? Not to the small child. Is a lie something one truly believes oneself. No, clearly that wont wash either.
Googling gives, a trivial lie, an insignificant or childish lie. But who draws the line and where is the line drawn?
That line is so flexible, so changable as to be anywhere.
Santa's a fib, a lie, a deception, but he's also a 'Wonder of the World' for little kids. Which is worse, to never know the wonderment of seeing the presents there and the snacks gone and everything all sparkly and shiny, or to have to learn about the 'Santa Myth'? There are ways to teach it that make it a positive thing.
Case in point--from an on-line friend of many years duration. (Miss Meow, a teacher in El Paso, Texas.)
In our family, we have a special way of transitioning the kids from receiving from Santa, to becoming a Santa. This way, the Santa construct is not a lie that gets discovered, but an unfolding series of good deeds and Christmas spirit.
When they are 6 or 7, whenever you see that dawning suspicion that Santa may not be a material being, that means the child is ready.
I take them out "for coffee" at the local wherever. We get a booth, order our drinks, and the following pronouncement is made:
" You sure have grown an awful lot this year. Not only are you taller, but I can see that your heart has grown, too. [ Point out 2-3 examples of empathetic behavior, consideration of people's feelings, good deeds etc, the kid has done in the past year]. In fact, your heart has grown so much that I think you are ready to become a Santa Claus.
You probably have noticed that most of the Santas you see are people dressed up like him. Some of your friends might have even told you that there is no Santa. A lot of children think that, because they aren't ready to BE a Santa yet, but YOU ARE.
Tell me the best things about Santa. What does Santa get for all of his trouble?[lead the kid from "cookies" to the good feeling of having done something for someone else]. Well, now YOU are ready to do your first job as a Santa!"
Make sure you maintain the proper conspiratorial tone.
We then have the child choose someone they know--a neighbor, usually. The child's mission is to secretly, deviously, find out something that the person needs, and then provide it, wrap it, deliver it--and never reveal to the target where it came from. Being a Santa isn't about getting credit, you see. It's unselfish giving.
My oldest chose the "witch lady" on the corner. She really was horrible--had a fence around the house and would never let the kids go in and get a stray ball or frisbee. She'd yell at them to play quieter, etc--a real pill. He noticed when we drove to school that she came out every morning to get her paper in bare feet, so he decided she needed slippers. So then he had to go spy and decide how big her feet were. He hid in the bushes one Saturday, and decided she was a medium. We went to Kmart and bought warm slippers. He wrapped them up, and tagged it "merry Christmas from Santa." After dinner one evening, he slipped down to her house, and slid the package under her driveway gate. The next morning, we watched her waddle out to get the paper, pick up the present, and go inside. My son was all excited, and couldn't wait to see what would happen next. The next morning, as we drove off, there she was, out getting her paper--wearing the slippers. He was ecstatic. I had to remind him that NO ONE could ever know what he did, or he wouldn't be a Santa.
Over the years, he chose a good number of targets, always coming up with a unique present just for them. One year, he polished up his bike, put a new seat on it, and gave it to one of our friend's daughters. These people were and are very poor. We did ask the dad if it was ok. The look on her face, when she saw the bike on the patio with a big bow on it, was almost as good as the look on my son's face.
When it came time for Son #2 to join the ranks, my oldest came along, and helped with the induction speech. They are both excellent gifters, by the way, and never felt that they had been lied to--because they were let in on the Secret of Being a Santa.
Nice one DD.
I'm afraid Santa made the mistake of giving my boys those yellow flash arm bands to wear when cycling when they were small. Blotted his copybook and has never recovered his good reputation with them :)
Never mind. Santa is trying again as usual this year and has some very odd items up his sleeves for them....
Time Santa sent them on a Conversion Course to become Santa's themselves.... great idea. I love it.
A course I took years ago taught that the best things one does are things that no one else ever knows about.... ie. exactly like you describe. I try to live like that. But hadn't thought of it in relation to xmas gifts.
Has anyone some new "Easy" Questions?
Kid's question but I don't know how 'easy'...
Why is the moth attracted to the candle/light?
It isn't.
It's trying to navigate in it's evolved manner by keeping the light source (evolutionarily the Moon) at a fixed angle to fly in a straight line. With a very distant light source (the Moon or Sun) this works very well, with a point light source (like a candle) it results in a spiral flight path which ends in the candle flame. OOPS!
Too sad an answer for a New Year. I prefer to believe moths adore the scent of candle smoke (including new-fangled flavours) which is stronger than the sun or moons cos closer (Quasi was correct on the aspect of distance). They therefore follow the scent, depending on the amount of ventilation in the room which accounts for an indirect path, and reach moth heaven, full on scent of choice. The reason you never see another moth follow suit quickly is they are repelled by the burning moth smell and will not approach until the burning candle smell is smellier than the burning moth spell.
Another question, a special Happy New Year Question:
Why does a teaspon (metal not plastic) popped up side down into the neck of an open bottle of champagne prevent the bubbles from disappearing when the champagne needs saving for another day?
Quote from: Griffin NoName The Watson of Sherlock on January 01, 2007, 04:49:51 AM
Too sad an answer for a New Year. I prefer to believe moths adore the scent of candle smoke (including new-fangled flavours) which is stronger than the sun or moons cos closer (Quasi was correct on the aspect of distance). They therefore follow the scent, depending on the amount of ventilation in the room which accounts for an indirect path, and reach moth heaven, full on scent of choice. The reason you never see another moth follow suit quickly is they are repelled by the burning moth smell and will not approach until the burning candle smell is smellier than the burning moth spell.
Another question, a special Happy New Year Question:
Why does a teaspon (metal not plastic) popped up side down into the neck of an open bottle of champagne prevent the bubbles from disappearing when the champagne needs saving for another day?
Actually, this one was on MythBusters awhile back-- and they concluded it didn't actually do anything .. ::)
The people I am staying with use the spoon trick and it works for them. If it doesn't work, this must imply that the Champagne they drink would not lose its bubbles anyway, or there is some strange set of conditions in their home environment. Or they are lying. Clearly more research needed.
Arrr...
Why do biscuits turn soft when they're stale, but cakes turn hard?
Mmm... someone didn't read the thread? ;)
Quote from: Swatopluk on page 2 on November 18, 2006, 11:18:16 AM
Concerning the cake and biscuit question
Clearly depends on the type. One thing is clear: there is a dynamic exchange between the atmosphere (gas with "dissolved" water) and the solid object. The cake could be seen as a sponge that already holds water while the biscuit is more like a dry sponge.
The atmosphere being big will have a more or less constant humidity (let's ignore the weather for a moment) while in the wrapping of the eatables there is not much air, i.e. only a fixed small amount of water. In the wrappers there will be an equilibrium between water in the eatable thing and the surroundings. In the open air a dry good will suck water from the surroundings until there is again an equilibrium. If on the other hand you have a humid good the not saturated air (unlimited capacity) will suck the water out until there is either an equilibrium or there is no accessible water left. Goods will dry often at the surface only because the water at the center cannot easily come to the outside (and the other way around in dry food, soggy on the outside but still dry inside).
That food gets soggy in the fridge is slightly different. Cold air can hold less water than hot air. The fridge permanently exchanges the air inside itself. The air from outside is cooled down and will lose some of its water content that will end either as condensation or will be sucked up by food stored in the fridge. In the oven you have the opposite effect. The hot air can hold more water and will suck it from the baking goods.
I have to admit that there are a lot of aspects concerning this that I do not completely understand. There is probably another effect of water tightly and loosely bound in the food. We will not notice it in the former case but if by some effect the tightly bound water becomes loose we will.
A nice experiment demonstrating something similar can be carried out at home too.
Get some copper sulphate. It is blue and apparently dry. Now heat it ( a gas stove would be best) and it will turn colorless/white. If you keep it under dry conditions it will stay that way but under humid conditions it will turn blue again without seemingly getting wet (at first). If you have precise scales you can show that the blue dry salt is slightly heavier than the white dry salt. In the blue version the water is bound so tightly that it cannot be detected.
Interestingly, not too long ago I placed a bag of burger buns (in their package) in the fridge and after a while some turned hard, the others where almost wet, inside
the same bag (I believe the ones on top were hard and the ones below wet). Some interesting dynamics there.
Water following the pull of gravity? I have made the experience that items in the lower parts of the fridge and at the back get more water even when proteced against condensed water dropping down. I can only guess that it is so because the lower parts are cooler (natural air distribution) and the back too (the cooling spirals are located there).
Quote from: The Black Spot on January 31, 2007, 01:46:37 AM
Arrr...
Why do biscuits turn soft when they're stale, but cakes turn hard?
Ye blaggard...you've got cake on board yer ship now!
Could a moon of a planet always be in the shadows by having a period of exactly one year or would such an orbit be mechanically impossible?
Unless my physics fails me, yes, it would be possible.
Going back to Kepler, assuming a circular orbit:
(P/2pi)2=a3/[G(M+m)]
where:
P = Period (i.e. time for one orbit)
a = semimajor axis (i.e. distance from the Sun to the planet, or from the planet to the moon
M, m = masses of the bodies in question
So, for the lunar orbit to be exactly one year, the two periods would be equal, or:
as-p3/[G(ms+mp)]=ap-m3/[G(mp+mm)]
(note: s = sun, p = planet, m = moon)
Assuming that the masses and the distance from the sun to the planet are fixed,
ap-m3 = as-p3*(mp+mm) / (ms+mp)
So, for any particular set of sun, planet and moon masses, there is always a distance that you can plunk the moon at that will cause an orbital period of once per year
... for a circular orbit, at least. I'd attempt to figure it out for an eliptical orbit, but I'm worried that would make my brain explode.
Same for me, the ellipses are beyond my capabilities (that are therefore elliptical ;))
A second question would be, whether that orbit could be stable, if one includes the gravity of the sun in the calculations. If not, would an orbit that effectively is always in the light be stable (i.e. moon permanently between planet and sun instead of planet between moon and sun)? Is it a Lagrangian point?
Edit: Yes (http://en.wikipedia.org/wiki/Lagrangian_point), those are L Points but unstable ones.
Quote from: Swatopluk on March 16, 2007, 03:05:04 PM
A second question would be, whether that orbit could be stable, if one includes the gravity of the sun in the calculations.
I don't see why not.
Another way of looking at it (and probably the way I should've used above) is to consider the planet-moon system as one body with its own mass and centre of gravity. In terms of orbit around the sun, this system would behave just like a planet.
Then if you look at the moon-planet interaction, you can consider that as a separate system...
... oh, but hang on. That system would be in an accelerating frame of reference. That would make things... goofy.
QuoteIf not, would an orbit that effectively is always in the light be stable (i.e. moon permanently between planet and sun instead of planet between moon and sun)? Is it a Lagrangian point?
Hmm... we're beyond my expertise, but would there be a Lissajous orbit* that satisfies the original problem?
*i.e. just outside Lagrange - I think ZZ Top wrote a song about the orbital mechanics involved. ;)
Umm. I don't think it would work. What you are proposing is in effect a tethered pair of objects - that is two objects with the same solar orbital period but at different orbital distances. This can work if the two objects are tethered and the net result is tidal forces providing a stretching force along the tether with the closer (to the sun) object orbiting faster than it would on its own and the outer object orbiting slower than it would on its own. This idea has been proposed as a way to provide artificial gravity on a satellite - two flat surfaces tethered and in orbit, with each feeliing "up" as being in the direction of the other. In the case of a planet and moon, gravity alone is no where near strong enough to overcome the tidal forces that would ensue and so the pair would very quickly move apart. Actually at the difference in their nominal orbital velocities.
Sibling Bluenose
What if the two objects were entangled?
Another Oldie
A worm sits at one end (or near it) of a rod that permanently expands.
It begins to crawl towards the far end with a speed lower than the expansion of the rod.
Will it ever reach the end and, if yes, how long will it take?
Given parameters
L = length of the rod at the start
v1 = expansion speed of the rod
v2 = crawling speed of the worm
x0 = starting position of the worm
The end of the rod where the worm is starting is considered non-moving and the rod expands uniformly, i.e. the forward speed at a point x[0;L] is (x/L)*v1
Ack! Integrals!
I have an Easy Question.
Why is this thread called Easy Questions?
I couln't be bothered doing the math, and frankly I'm not sure if I remember how to do the math, but I'm pretty sure the answer is, it depends on the starting position.
(Ignoring relativistic effects) at any given point xn the velocity of the worm (v3) is equal to its crawling speed v2 plus a proportion of the expansion of the rod v1 equal to the ratio of the worm's position xn and the length of the rod L, in other words v3=v2+v1(xn/L). So for any starting position x0 where v3 is greater than v1, the worm will indeed reach the end.
Thus if v3>v1 or if (v2+v1(x0/L)>v1, then the worm will get to the end, otherwise it won't make it.
Hmm, looks like it did the math after all.
These are called easy questions because they are questions that look like they are simple, but often require complex or subtle answers to explain. I guess we are saying that the question may well be easy, that does not say anything about the answer!
Quote from: Sibling Lambicus the Toluous on March 16, 2007, 03:30:25 PM
QuoteIf not, would an orbit that effectively is always in the light be stable (i.e. moon permanently between planet and sun instead of planet between moon and sun)? Is it a Lagrangian point?
Hmm... we're beyond my expertise, but would there be a Lissajous orbit* that satisfies the original problem?
*i.e. just outside Lagrange - I think ZZ Top wrote a song about the orbital mechanics involved. ;)
I think they also wrote one about a proposed solution "I'm a Fool for Your Stockings, I believe."
The proof that the worm will reach the end in the end looks relatively easy.
If it does not crawl, its relative position on the rod does not change. If it crawls even at the lowest speed it improves its relative position and thereby its speed toward the end.
The latter fact should prevent the function from becoming asymptotic.
When it reaches the position on the rod where its own speed and the positional expansion speed add up to the total expansion speed its distance from the desired end reaches its maximum, then begins to shrink.
I haven't done the calculation yet how long it actually takes but I remember that the numbers get huge.
Quote from: Bluenose on March 29, 2007, 03:12:03 AM
I couln't be bothered doing the math, and frankly I'm not sure if I remember how to do the math, but I'm pretty sure the answer is, it depends on the starting position.
[...]
Thus if v3>v1 or if (v2+v1(x0/L)>v1, then the worm will get to the end, otherwise it won't make it.
The starting point's given: it's the fixed end of the rod.
And the worm will make it, since it's given that v
2 > v
1. Therefore, v
3 > v
1 as well.
Wait... hang on. I think I was making the problem more difficult than it had to be. Is the time taken just
L/v2?
I haven't done the math, but I think if you look at the worm's movement as a percentage of the instantaneous length of the rod, you'll find that the change in percentage is constant with time; all the terms with v
1 in them should drop out of the equation.
Edit: I tried the math and it got messy, but I think it works in concept: at any point in time, the additional speed the worm receives due to the expansion of the rod is equal to the expansion of the rod itself (as it has to be, the way the problem is set up). Therefore, the faster the rod expands, the more extra speed the worm will receive.
I'm fairly certain that over the entire length of the rod, this extra "push" will result in a "bonus worm distance" (i.e. the extra distance travelled by the worm above and beyond what it would have done at speed v
2) that will work out to the final length of the rod minus the initial length.
The solution I have come up with
x= v1*t+ integral[0;t]{v(x,t)dt}
v(x,t)= v2*(x/L(t)) = v2*x/(L0+v2*t)
with q=L0/v2
=> v(x,t)=x/(t+q)
integral[a;b]{x/(t+q)}dt = [x*ln(t+q)]ab*
=> x = v1*t + [x*ln(t+q)]0t
=> x = v1*t/(1+ln(1+(t/q)))
Unfortunately, this equation can't be brought to a form t= f(...) because one t is in the logarithm, the other isn't.
Thus with x=L0 one would have to solve an implicit equation to get the value of t, when the worm reaches the end of the rod.
*[f(x)]ab means f(b)-f(a)
I just looked up the riddle on the net.
My thought process was obviously far too complicated.
The way is to start with a sum and then go to the integral.
First it is assumed that the rod does not expand continuously but in jumps.
The crawling distance for the worm can be calculated for each interval. first 1/x of the band, then 1/(2x), 1/(3x).....
This defines a sum.
If the time intervalls are shortened indefinitely the sum turns into an integral.
The solution for
v1= 1cm/sec
v2= 1m/sec
L=1 m
is
t = e100000sec ~ 1043422 years
Old and grey he will be when reaching his goal.
I say take the rod, the worm, some string...and go fishing!
Or at least sit around pretending to fish while you nap.
Quote from: Swatopluk on March 29, 2007, 03:13:35 PM
The solution for
v1= 1cm/sec
v2= 1m/sec
L=1 m
is
t = e100000sec ~ 1043422 years
Old and grey he will be when reaching his goal.
Is that with v1 and v2 defined as you did before? If so, that seems too long. Is there a unit prefix missing there? 1 m/s is a quick walking speed.
But look at it this way: if the worm were on the table next to the rod, rather than on the rod itself, it would take 1.01 seconds ( i.e. t = (v2-v1)/L ) to reach the end of the rod.
Since in the original problem, the worm is going faster than v2, the time taken must be less than 1.01 s (assuming the units are okay).
Sorry, confused v1 (rod) and v2 (worm)
And the solution quoted seems to imply a 1km rod, not a 1m one.
The solution looks confusing but the trick is to take L as a constant (tt: reduced length) and to change from an absolute speed of the worm to a relative one (i.e. in comparision to the reduced length L). Thus the term dependent on both x and t can be dropped and the worm term becomes essentially dimensionless. The integration is made from the time the rod reaches its initial length to tend when the worm reaches it*. The integral is then set as 1 (= 1 length) and t isolated
* t=0 would be a point back in time when the rod had zero length.
I should have had that idea myself but I thought that a transformation of coordiantes would make the problem more not less difficult.
Now, where do we get such an elastic rod and a worm with sufficient life expectation?
I just washed my white towelling robe in deep blue detergent. Why is it still white?
I imagine you will tell me all about light. But can you phrase it in a way a three year old would understand?
It is a dye that does not stick to the cloth. Thus it can be rinsed out completely.
If the little thingies that give the color would prefer to stay with the fibres instead of going for a swim, the situation could look different. Just don't ask me why the foam is white independent of the color of the stuff the foam came from.
Silly...it's
MAGIC
Okey Dokey then yer blaggards...
If you have to squeeze through a small gap you breath in.
Why should taking a large amount of air into your body make you smaller?
Hey Spot, it depends where you draw the air into :mrgreen:
I think it's not breathing in but holding your breath.
To breathe in could be just a safety measure in case that you get stuck.
If you breathe out and then get stuck, you could be in trouble of suffocation.
----------------------------------------------------------------------------------
Let's say you have no idea about star constellations (or are on a planet with different ones from ours and no map), have no compass (neither magnetic nor gyroscopic) and no clock/watch, but want to find the exact direction towards the next geographic pole (no telephone pole ;)).
How could you do it with simple tools?
Erm... the sun? Or is it underground/always clowdy/in the forest/etc?
---
I have a question: this happens to me from time to time, take a new book and start reading it slightly bending from the cover pages. If you put the book on its back the cover (and sometimes a few pages) is lifted. Now rest the book on its cover and -oh surprise- the back page begins to lift.
1. Does it happen to you (or is only me)?
2. well... why?
1. Sometimes for paperbacks. With hardcover books, I can't recall it happening.
2. Two possible reasons:
- you bent the back cover slightly while reading the book.
- as you read, the spine became bent by your turning the pages at the front. This exerts force on the rest of the book. Since the back cover and back page is light enough, it gets lifted when you put the book down.
I'd vote for option 2 (force exerted by or on the spine).
Concerning the North direction. I mean you can watch the sky and it is clear. The sun would be in my opinion pretty useless (and there could be more than one) because you have no prior knowledge about the tilt of the planet's axis (though you can get it by observing something else) or the calendar, daylength etc. And you have no clock available.
I will grant you an assistant that can do things while you do observations (that makes it easier but is not strictly necessary).
Actually, the sun is the go. Place a stick in the ground as near to vertical as you can manage, preferably in a sandy spot or one where you can mark the ground somehow. Make a mark in the ground for the tip of the shadow of the stick. Do this every so often. Note which direction the sun appears to be moving, to give you a general East/West alignment (the sun appears to move generally from East to West.) When the shadow is at it's shortest, the sun is either due North or South (of course, the shodow points the opposite direction.) To determin which, stand aligned and facing the North/South line (from the shadow) so that East is on your right (as determined earlier), North is the direction of the shadow (or the reverse as the case may be), heading away from you.
An alternative is to look at the night sky and draw a map of the brighter stars. Repeat this every hour or so during the night. By comparing the maps, you should be able to find the point in the sky (there may or may not be a star there, that would be just luck) around which all the others appear to be roatating. That point it the nearest celestial pole (you don't know yet whether North or South). The only exception to this case is if you are on the equator in which case the sky would appear to revolve around two opposite points of the horizon, one being the North celestial pole, the other the South. Resolve the ambiguity by observing which "side" the stars appear to rise from, this direction is East, place that on your right and the celestial pole in front of you is North.
The sun method could fail in a double star system, I think. I had the night method in mind.
The trick is to mark the East/West extremes of a few stars from a fixed observation point and then to find the middle point between those extremes. The line from the observation point to the marked middle point is the direction towards the next geographical pole. The North/South extremes (and then simply using a plumb line) are far less precise.
Btw, the Egyptians used that method to "North" their pyramids. The markings can still be found on the plateau.
Next question please ;D.
Why do I keep finding ways of avoiding writing my essay?
The same reasons I find to avoid doing my work I guess ;)
This question concerns disolving a soluble tablet (the sort that fizzes as it disolves) in water in a glass. Trying to drink from the glass whilst the tablet is still disolving would appear to be possible by turning the glass so that the fizzing tablet will not enter the mouth. However, turning the glass always results in the tablet maintaining the property of being at the point nearest the mouth, even when the glass is held upright and not tipped towards the mouth. Why?
Have you tried the same with a rectangular glass instead of a cylindrical one?
Turning the glass not necessarily also turns the contents, especially with a liquid of low viscosity as water (the gas may even reduce it further).
Drinking will likely cause a bit of suction that would affect the tablet too. Has using a straw the same effect?
I have a hexagonal glass which I could test. ;D
I assume this is an easy question. Actually it's two questions. No, it's three questions.
I've been watching science for the masses on TV again.
They start with speed of light stuff. Seeing into the past. Lots of this light from this star started out 150 years ago bla bla. Hubble, seeing almost to the edge of the visible universe.
How can we be sure it's the past? Couldn't our mindsets be fixed in a way that actually means we are seeing into the future and the end of the universe? (like the way the retina captures images upside down and the brain turns them the right way up).
Sceond question. In the beginning there was nothing. Flashes of many scientists repeating this. Just a second before the Big Bang, de nada. Good popular science.
What's the proof there was nothing? Experimental data?
Third question. Should I stop watching popular science and stick to the text books?
If the first were true then a mirror deposited far enough away could be used for long term weather prediction ;D (or the results of horse races).
The "in the beginning there was nothing" is anything but undisputed. One should keep the campus gun free for the sole reason of preventing duels bewteeen rivalling cosmologists. :o
TV for living nature, books for dead ;) Long live David Attenborough!
Quote from: Griffin NoName The Watson of Sherlock on May 06, 2007, 01:45:20 AM
Just a second before the Big Bang, de nada. Good popular science.
What's the proof there was nothing? Experimental data?
Always tricky when singularities are involved, but I guess one way of looking at it is having a "before" in advance of having a spacetime is a bit like having a horse race before you've evolved the horse.
Anyway, my limited understanding is that the very big brains currently think universes get created due to the collision of very big branes. Hope that's cleared things up.
So, we're back to the gigantic Cozmic Zombies lurching around, mumbling "Branes, branes"?
Sounds about right.
Quote from: Griffin NoName The Watson of Sherlock on May 06, 2007, 01:45:20 AM
I assume this is an easy question. Actually it's two questions. No, it's three questions.
I've been watching science for the masses on TV again.
They start with speed of light stuff. Seeing into the past. Lots of this light from this star started out 150 years ago bla bla. Hubble, seeing almost to the edge of the visible universe.
How can we be sure it's the past? Couldn't our mindsets be fixed in a way that actually means we are seeing into the future and the end of the universe? (like the way the retina captures images upside down and the brain turns them the right way up).
Sort of tied into this. I think. I don't think it's a stretch for most people (well, most people
here ::) ) to imagine the possibility of a universe that starts at a singularity and goes on forever (with equilibrium possibly reached at some point). So why does it seem completely counterintuitive to imagine the opposite - a universe that goes on forever into the past, and ending at a singularity sometime in the future?
I personally find the idea a bit discombobulating in itself, like waking up on the ceiling.
Quote from: Agujjim on May 07, 2007, 06:40:26 PM
Sort of tied into this. I think. I don't think it's a stretch for most people (well, most people here ::) ) to imagine the possibility of a universe that starts at a singularity and goes on forever (with equilibrium possibly reached at some point). So why does it seem completely counterintuitive to imagine the opposite - a universe that goes on forever into the past, and ending at a singularity sometime in the future?
Probably because of the way most people think of time and causality: things happened because of the things before them. If things stretch forever into the past, then there is no beginning, no "first cause" (to borrow the expression from those trying to prove God)... and ergo no "us".
Streching off into the future is okay, since we don't "need" it in order to have our here-and-now.
Quote from: Agujjim on May 07, 2007, 06:40:26 PMI personally find the idea a bit discombobulating in itself, like waking up on the ceiling.
One of my friends told me a story (probably untrue) about a rich man who made up one of the rooms of his mansion to be exactly like one of his main rooms, except it was built completely upside-down. Supposedly, when people passed out drunk at his parties, he'd put them in there and, for his own amusement, videotape them waking up.
;D
Quote from: Sibling Lambicus the Toluous on May 07, 2007, 06:54:57 PMOne of my friends told me a story (probably untrue) about a rich man who made up one of the rooms of his mansion to be exactly like one of his main rooms, except it was built completely upside-down. Supposedly, when people passed out drunk at his parties, he'd put them in there and, for his own amusement, videotape them waking up.
;D
This is one of the reasons I should never be trusted with large sums of money. ;D
(have always wanted a few rooms like that, and a host of other oddities.... theremin-circuit based 'sound sculpture' rooms that change according to your proximity to pillars, mirror arrays that allow the viewer to see the back of their own head, indoor lakeshore rooms).
Quote from: Agujjim on May 07, 2007, 07:14:13 PM
(have always wanted a few rooms like that, and a host of other oddities.... theremin-circuit based 'sound sculpture' rooms that change according to your proximity to pillars, mirror arrays that allow the viewer to see the back of their own head, indoor lakeshore rooms).
Your theremin room kinda reminds me of something I saw on TV years ago: an artist did up a sort of robotic sculpture (for lack of a better word) that consisted of several arms hanging down from the ceiling. The arms were made out of dried vines, so they looked more organic than mechanical, and he did his best to camoflage the motors in the arms.
The really funky thing was how they worked, though: each one was equipped with a microphone, and they "flocked". They'd act randomly until one heard a noise... then that arm would pan around to find the source of the noise. Once it did, it'd "tell" the other arms by way of DTMF telephone tones, and they'd all swivel around and point the same direction as the first arm.
He had the things rigged so well that they really had a "living" quality to them. When anyone walked into the room, they'd hear this other-worldly whistling and hooting, as all the other arms "look" up as well and join in the chorus. Whimsically freaky/freakishly whimsical, I guess.
Quote from: Agujjim on May 07, 2007, 07:14:13 PM
This is one of the reasons I should never be trusted with large sums of money. ;D
This is reminiscent of the Dilbert where Dogbert makes a fortune. After paying a businessman in a suit thousands of dollars to wallow in a puddle he says "I don't understand how rich people ever get bored".
Quote from: beagle on May 07, 2007, 08:25:49 PM
Quote from: Agujjim on May 07, 2007, 07:14:13 PM
This is one of the reasons I should never be trusted with large sums of money. ;D
This is reminiscent of the Dilbert where Dogbert makes a fortune. After paying a businessman in a suit thousands of dollars to wallow in a puddle he says "I don't understand how rich people ever get bored".
My favourite "what I'd do if I was rich" story is from Canadian Comedian Brent Butt... it involves buying the town of Red Deer, Alberta and riding a giraffe down the main street while wearing a Viking helmet and swinging a bag of gophers around his head.
Quote from: Agujjim on May 07, 2007, 06:40:26 PM
....So why does it seem completely counterintuitive to imagine the opposite - a universe that goes on forever into the past, and ending at a singularity sometime in the future?
How about a Toadfish pact that we all set our clocks going in reverse? If a whole community reversed time, may be we'd crack all this ?
Quote from: Sibling Lambicus the Toluous on May 07, 2007, 08:32:41 PMMy favourite "what I'd do if I was rich" story is from Canadian Comedian Brent Butt... it involves buying the town of Red Deer, Alberta and riding a giraffe down the main street while wearing a Viking helmet and swinging a bag of gophers around his head.
So, he wants to be in the Stampede parade then? ;)
You'd have to be pretty rich to pick up Red Deer these days... maybe Medicine Hat or Moose Jaw SK instead? ;D
Quote from: Griffin NoName The Watson of Sherlock on May 07, 2007, 10:38:36 PM
Quote from: Agujjim on May 07, 2007, 06:40:26 PM
....So why does it seem completely counterintuitive to imagine the opposite - a universe that goes on forever into the past, and ending at a singularity sometime in the future?
How about a Toadfish pact that we all set our clocks going in reverse? If a whole community reversed time, may be we'd crack all this ?
I have an old battery operated clock from the late 70's that runs backwards if you putt the batteries in wrong. I'll try to find it.
I used to keep it running and on display in my living room. ;D
There is a theory that 'Merlin' of King Arthur's court, was living backwards in time...or was that the dream I had after finishing off me Holy Grail Ale!!
Still less problems than with the Douglas Adams linguistic time paradoxes.
Back to the subject, didn't Hawking or someone else discovered that a black hole can be unstable under certain conditions? The point is that perhaps (and I am talking out of my @$$ now) after certain amount (several galaxies) of matter a blackhole can explode creating the equivalent of a big bang, it would be a singularity and who knows what would be the composition of the resulting nebula, think supernova on lots of steroids. I may be perfectly possible that some stuff may have been outside of said black hole (perhaps not emitting light?).
A back hole loses energy (and therewith mass) through the Hawking radiation. But the bigger it is the less it loses. The postulated black mini holes are small enough to lose enough that way to reach the end of their lives within the time the universe exists in its current form. If they pass the minimum treshold they explode in a very hot outburts of radiation (for some time the so-callled gamma bursts were suspected to be exactly that). A large black hole like The Beast in the center of our galaxy has a life expectancy that is many orders of magnitude higher than the current age of the universe.
According to popular science, the Large Hadron Collider (http://en.wikipedia.org/wiki/Large_Hadron_Collider) may well sort all this out for us; if it does, we won't be around to know it has. Probably. I find the Uncertainty Principle comforting.
Before this thread dies an old classic:
Why does a three legged table or stool not jiggle (correct verb?)?
Answer in a way that "normal" people can understand ;)!
Because 'wobbling' (better verb - 'jiggling' more properly refers to Boobs) is oscillation between two or more stable states. Three-legged stools or table one have one stable state (all three legs on the ground).
"Jiggling' may invole 'osculation' rather than 'oscillation'. :P
A "normal" person may believe a stable state is one where the auotmobile is banned.
Quote from: The Meromorph (Quasimodo) on July 08, 2007, 03:05:17 PM
"Jiggling' may invole 'osculation' rather than 'oscillation'. :P
Sounds like you are one lucky guy... ;)
:mrgreen: :mrgreen:
Mero, the answer is correct but not everybody would understand the "single stable state". Please explain for dummies why it exists with 3 legs but not with more.
Additional: Could there be a rigid body that is unstable independent of spatial position (in layperson's term: would fall over however you put it on a horizontal surface)?
Apart from a sphere? (otherwise it sounds like a perpetum mobile)
That is indeed the most practical answer. But why exactly?
Quote from: Swatopluk on July 08, 2007, 06:21:20 PM
Mero, the answer is correct but not everybody would understand the "single stable state". Please explain for dummies why it exists with 3 legs but not with more.
For stability, the 'center of gravity' must be inside the shape defined by a string runninning around theplaces where the legs touch the ground. outside of the legs (at the bottom).
With one or two lplaces touching, there
is no shape to be inside. With three legs, the stool falls until the third leg touches the floor. With more than three legs the stool still falls until three legs are touching the florr, but it's possible for other legs to not be touching the floor. If the center of gravity move outside the current three-leg shape, the stool will fall again until another leg hits the floor, therfor providing a shape again.
If you say a person might not understand center of gravity, then they'll have to learn it, because it's required for
any explanation of this.
Quote from: Griffin NoName The Watson of Sherlock on July 08, 2007, 03:47:26 PM
A "normal" person may believe a stable state is one where the auotmobile is banned.
::looks around for a 'normal person'::
All Clear!!
Three legs: The reason a three legged stool is stable is because three points always form a plane. So long as the lengths of the legs are approximately the same so that the centre of gravity falls within the triangle formed by the leg ends when placed on the floor (if one leg was very long for example, the stool would fall over, but I am talking about the usual case here) amd obviously also if the floor is sufficiently level that the same occurs (it wouldn't work on a 45o slope for example) then there will allways be "matching" of the three points at the bottom of the chair leg and the three points on the floor immediately below the leg ends. Since three points always form a plain, the two sets of three points will always coincide.
If there are more than three legs, if the legs are not all exactly the same size then the four points will form two planes and unless you are very lucky and the floor just happens to have the same two planes formed by the four points below the leg ends, which is unlikely, then the chair (or table) will rock. Of course the same is true if the chair is even and the floor is not. In either case, especially with tables, the usual approach to this is to adjust the length of one of the legs either with a leg end designed for this purpose or with a wad of paper (usually serviettes in the restaraunt situation).
Now the question is: if for a 3 dimensional environment 3 legs generate a plane (and stability) how many legs for a 4 dimension world? (or better for a n-dimensional world)? :mrgreen: :mrgreen: :mrgreen:
4 dimensions? don't know about legs, but sounds like a lot of serviettes.
Quote from: The Meromorph (Quasimodo) on July 08, 2007, 03:05:17 PM
Because 'wobbling' (better verb - 'jiggling' more properly refers to Boobs) is oscillation between two or more stable states. Three-legged stools or table one have one stable state (all three legs on the ground).
"Jiggling' may invole 'osculation' rather than 'oscillation'. :P
:ROFL:
mostly I just read this--- my siblings are way to smart for me- but I get it on an elementary level (usually)
but the word Boobs just jumps out at one
OM!
Quote from: Sibling Zono (anon1mat0) on July 08, 2007, 11:29:00 PM
Now the question is: if for a 3 dimensional environment 3 legs generate a plane (and stability) how many legs for a 4 dimension world? (or better for a n-dimensional world)? :mrgreen: :mrgreen: :mrgreen:
Well, actually a plane is always a two dimensional construct. Thus no matter how many dimensions for a given frame of reference, three points will still form a two dimensional object lying on a plane that intersects at least two of the dimensions of the reference (it may be more, depending on where the points are located.
Strictly speaking you are correct. My thoughts were regarding the fact that in a 3D space any 3 different points define a unique 2D plane within such space. If we go up to a 4D space there is an infinite amount of 2D planes with 3 points (a 4D table would tumble) therefore you need 4 points to express a unique 3D *plane*.
The explanation I'd give for the hypothetical object that is unstable in any position would be:
In a stable (or at least metastable) state the center of gravity is in a position that any shift of the object would move the center of gravity upward (i.e. requiring a nonnegligible force). Because in a rigid body the center of gravity is fixed as related to the body there must be a spatial orientation where the center of gravity lies lowest => stable state. The lone exception would be the sphere* because here the center of gravity does not shift because all points on the surface have the same distance to it.
*or an object in the same symmetry group like hollow spheres, concentric hollow spheres etc.
-----------------------------------------
Next questions:
1. Why are modern submarines much faster in the submerged state than on the surface?
2. Could a hollow metal sphere be made that would float in the air when evacuated?**
** a macroscopic one, not one of a size lower than 1 mm
I'll take on the submarine one.
When on the surface of the water, a moving body will create surface waves, expanding from the object exactly like ripples on a pond from when you throw a stone into it. Because of the size of a ship (or boat in the case of a submarine) the amplitude of the waves is much greater than those from the stone. However, the velocity of any powered vessel is usually (almost always) greater than that of the waves themselves, and so the vessel is always moving faster then the lead waves and crashing into undisturbed water. This is entirely analagous to the shock wave of a supersonic aircraft, and like a supersonic aircraft it takes a considerable amount of energy to do it. This is the reason why modern powered vessels have sharp bows, just like supersonic aircraft to minimise the drag caused by shockwave and to keep the hull of the ship, within the cone of the shockwave (called a wake in this case) so as to minimise the energy requirement.
On top of that there is the drag caused by the shape of the hull of the vessel and this is equivalent to what in aerodynamic terms is called form drag. Once submerged the submarine only has this type of drag and the drag induced by the surface wake (shockwave) is no longer present and only the form drag exerts itself. The most efficient aerodynamic (or hydrodynamic) shape is the so-calles teardrop shape which modern submarines make a reasonable approximation of. Similar effects to supersonic flight will only occur once submerged as the vessel approaches the speed of sound, but since the speed of sound of water is higher than in air, (ie > 700 knots or so) it is is not an issue for any submarines I am aware of, including torpedoes and so on. BTW, modern surface ships, particulalry very large bulk carriers where efficiency equates to dollars, often have large bulbs below the water line at the bows to gain benefit from this more effient subsurface shape, but they still have to cut through the wake.
Hope this is a bit clrearer than mud.
As for the metal globe, in prinicple I believe that this could be done, so long as there is an alloy of sufficient strength to be able to withstand atmospheric pressure. This metal would need to be light enough that the volume of air displaced has a lower mass than the shell of the metal of a thickness sufficiently strong to withstand the pressure. I do not think that there is such a metal, but I could well be wrong.
I am not completely sure about the sphere either but I think/guess above a certain size the strength of the wall can be kept constant, and then it is just a matter of increased diameter. For "practical" reasons a half-sphere/ellipsoid with flat bottom may be preferable to keep the structure from collapsing under its own weight with a minimum of internal stabilizing structures.
In a related area, would a gas-filled or evacuated tube of high diameter submerged in a high density incompressible fluid (i.e. lower pressure on the top, significantly higher on the bottom) still have the circle as ideal profile or would it go towards an ovaliform shape? In the latter case, would the "sharp" end be top or bottom?
That's one I simply do not know the answer for.
Now something simply crazy. How fast would a rigid spherical body of earth mass and diameter have to rotate to cancel gravity on the surface (i.e. centrifugal force = gravitational force towards core)?
For a small sphere the material could theoretically be a fullerene (like carbon nanotubes and buckyballs) although I don't know if it is possible to make it as a macroscopic structure.
About the earth like planet, wouldn't the core be spinning even faster to make the surface spin that fast? It would create a huge amount of heat because in the equator it might cancel the forces but the closer you go to the poles, you'll have less centrifugal force. My guess is that it would tear the planet apart in no time.
That a normal planet could not take those forces is pretty obvious (neutron stars on the other hand can but they are both smaller and heavier). That question was a merely theoretical one (therefore the "rigid spherical body" part).
Answer is actually more easy than I thought. It is the speed of a circular orbit at the earth surface, i.e. about 7900 m/s.
For comparision: the actual speed at the equator is just 463 m/s, about a 17th of the necessary value.
I hadn't thought about the effect being limited to the equator when I put the question up, I admit, despite it being obvious.
Yep, mg= mvv/r
solved for v is the simplest way I can think of.
Quote from: Swatopluk
In a related area, would a gas-filled or evacuated tube of high diameter submerged in a high density incompressible fluid (i.e. lower pressure on the top, significantly higher on the bottom) still have the circle as ideal profile or would it go towards an ovaliform shape? In the latter case, would the "sharp" end be top or bottom?
My immediate reaction is that if the tube is lighter than the fluid that it displaces then the shape will depend on the position of the mounting points holding it in place, with it arching upwards at the furthest positions from those points. I'd guess it would try to obtain a cross-section similar to that of a hot air balloon, but be constrained in its horizontal movement if held in place (depending on its supports).
Without constraints I'd expect a unifom hot-air balloon-oid cross-section, but that's a guess (don't fancy messing with the appropriate calculus of variations). Not sure how much of the HAB shape is due to non-uniform temperatures within it and the weight of the basket dangling precariously beneath it.
I think the balloon of today is designed that way. Early ones also had more spherical forms on occasion. The first Montgolfieres looked more like lightbulbs with socket.
You are probably right about the mountings being the true stress points but let's assume the tube was heavy enough not to float.
The larger the beast, the longer it tends to live. How long did the largest dinosaur live for?
Iirc the estimate is about 80-100 years but size is only one of the criteria determining that. Animals with slow metabolism tend to get older, those with very high die young (elephant turtles vs. jerboas). On the other hand the older an animal gets, the bigger it can become. Of course architeuthis has a very short lifetime (about 5 years iirc) but grows from tiny to huge. But squids are high metabolism creatures, so that would account for it.
Perhaps we should draw up longevity rules:
Taste bad.
Have a slow metabolism.
Don't provide any useful product.
Have a very nasty bite.
Have a nasty temper.
Live somewhere inaccessible.
Try and be adopted as sacred by the local tribe, or failing that GreenPeace.
Doesn't work. I meet most of that list spot on, and my longevity is seriously in question...
I have Chasing Playback on my HD recorder which is a truly wonderful invention. But why is there no Chasing Playforward ? it'd be so useful when I have to go out before the programme is due to finish, especially in whodunits.... :mrgreen:
Wait, does Greenpeace adopts seniors? That sounds like a nice prospect... ;)
What makes dough so extremly sticky, while none of its components has that character?
Usually it is the gluten protein, in combination with water.
(chemistry would be the really short answer) ;)
As I understand it water makes it possible for the gluten protein chains to attach to each other building gluten strands. Fat inhibits the formation of long gluten strands that's why a "crusty" dough like a pastry or shortbread dough often has a higher fat content.
http://en.wikipedia.org/wiki/Gluten (http://en.wikipedia.org/wiki/Gluten)
And why are the gluten strands sticky?
Shouldn't it just behave like rubber? (that question should be quite tricky :mrgreen:)
I don't now, maybe Aggie can explain later he's the one with the Chemistry Fu. ;)
To me chemistry is a equivalent to magic...
And I shouldn't really be trusted with a magic for kids kit nor a chemistry for kids kit... ;D
I think the same about physics ::)
Swato, you have been evil, why don't you answer the questions to which you already know the answer?
:devil2:
gluten strands are sticky because otherwise they would be useless for making dough. God made them that way so we would not starve.
Quote from: Sibling Zono (anon1mat0) on September 24, 2007, 12:44:54 PM
Swato, you have been evil, why don't you answer the questions to which you already know the answer?
:devil2:
That would be showing off (and I would have to look it up)
The simple answer: adhesion
But that is about as useful as "why is water coming fro the sky?" "because it is raining" = a tautology
Edit: I looked it up (Sorry, it's German)
http://www.foodmultimedia.de/brotbackwaren/archiv/index.php3?id=1365
Seems that there is still a debate about the exact reason. :o
Silly boy peoples. This is a COOKING answer.
So it won't fly apart when it gets hot and thus make the oven messy!
Banged grains, good. Exploded bread, bad.
:mrgreen:
Same reason as babies have sticky hands. For clinging onto mother's back without falling off during trips across the savanah, possibly between cooking pots.
I think love makes them cling together. :mrgreen:
That was the idea of an ancient Greek philosopher (pre-Socratic, Xanthippe didn't like her husband to comment on kitchen matters).
Why was there no 90th anniversary of the discovery of America*?
(The answer is not that celebrating was not yet common)
*by Columbus (not the Vikings, Irish monks, prehistoric men etc.)
The plebs were too busy rioting about the theft of days from their lives due to the calendar switch?
Or an astrologer had predicted George W?
----
By the way, studies by British car insurers show astrologers have the lowest accident rate; doctors the highest.
Easy question: how do I become an astrologer?
beagle got it right. The 90th anniversary would have been on a day that did not take plave due to the switch from Julian to Greogrian calendar
Griffin, that's written in the stars what's in the cards for you :mrgreen:
There are some (otherwise reputable) universities where one can officially study astrology, btw.
Okay, back to everyday observations.
I find that water cookers* that have collected a lot of scale/fur/tartar/"chalk" cook much louder, while a new or recently cleaned one cooks almost without making any sound at all. WHY?
*I mean not big boilers to heat your bath but the 0.5-2 l electric things to provide hot water e.g. for tea
Mineral solids are mineral solids? And when agitated (by heated water, which produces motion)--they make a sound?
But the tea pot gunk collects on the bottom, I would think. I certainly wouldn't boil water with an ooky one, so I assume that Swato would not.
Maybe it's an uneven distribution of heat? The crud on the bottom would alter the path of the heat, I think. So it makes funny noises.
I dunno. BSing right there.
I have this Thing that looks like a roll of steel string I put in my kettle.
It attracts all the limescale and you can just wash it out under a running tap.
Naturally, it rattles around.
That's why my kettle makes a lot of noise. ;)
The scale is only on the heating spiral (I wash out the thing before any new water is boiled).
From time to time I put acetic acid into it and let it boil. Afterwards the metal parts are perfectly clean.
So, the effect must be caused by the different surface structure and or heat conductivity of the heating spiral.
I simply do not know how how (although I could talk for awhile about the heat transition from surfaces to liquids and the temperature dependence because that is a standard exam question in technical chemistry).
:)
I remember playing with that stuff last year in my honors chem class. Fond memories of acetic acid.
So would the crud on the bottom of the pot affect the heat spiral? Even by a little bit?
New question!
Every time I want to go out for a photo walk, it rains. Every damn time. Why?
Murphy's laws are very clear about that.
:mrgreen:
I say we find Murphy and take away his pen so he has to quit writing laws.
I vote we punch him as well.
But! It did clear up today! As I walked out of the doctor's office this morning, the clouds broke and wonderful, soothing sunshine came out. It made me happy.
Ok this isn't exyactly science, but it is logic which is the next best thing.
There's a lift (elevator). It goes between floors G 1 2 3.
The doors of the lift on floors 1 and 2 have panels showing current floor number of the lift and an up arrow call button and a down arrow call button which can be pressed to call the lift.
Inside the lift is a disembodied voice continually and constantly proclaiming "lift going up" or "lift going down".
This voice can be heard at all times on any floor up to about 500 yards away. It is a very loud voice. Deaf people have an advantage.
All signs and buttons in and around this lift are also in braille.
On entering the lift, by observation and personal usage, everybody presses the button for the floor they want. The lift continues up or down, or changes direction accordingly. So does The Voice.
There is virtually no cross or bi-personal traffic. ie. normally only one person or (grouped) persons use the lift with a single destination. The lift travels fast with distance between floors being minimal. It then continues to go up and down by itself empty - usage is sporadic - with The Voice (female) talking to herself.
Is it necessary to have both an up and down arrow call button?
Only if The Voice deems it necessary.
A valient try Scribbli which wins you a hug.
However, The Voice, I believe, has a different raison detre.
It's other functionality is a repetative repeating of the phrases "Doors Opening" and "Doors Closing".
It seems to possess an almost demonic irritating belief that it can fool excited and anticipatory people into rushing up the corridor thinking there's a chance of seeing Jim Morrison.
With just 4 levels a simple call button should be enough. For a larger building, especially with more than 1 lift I'd prefer a system where the exact destination can be chosen outside the elevator, so the services can be coordinated strategically. While we are at it, a weight sensor would be useful, so a fully occupied cabin would not stop on a call, if another with less people in it is nearby.
Quote from: Griffin NoName on December 30, 2007, 02:17:36 AM
The lift continues up or down, or changes direction accordingly.
This means the elevator will go up or down, whichever you need, after it arrives.
Quote from: Griffin NoName on December 30, 2007, 02:17:36 AM
There is virtually no cross or bi-personal traffic. ie. normally only one person or (grouped) persons use the lift with a single destination.
And this means that (almost never) will anyone else be using the elevator going in a different direction than you want.
Everything else described is superfluous.
All you need is a call button, not up and down buttons.
And the voice says,
"Lift going down".
Quote from: Swatopluk on December 30, 2007, 08:38:28 AM
While we are at it, a weight sensor would be useful, so a fully occupied cabin would not stop on a call, if another with less people in it is nearby.
Yes, provided the cabins are side by side not one above another ;)
There are by now elevators with several independent cabins in the same shaft (only useful for very tall buildings).
A typical ignorant question by a city-dweller (me): Do chicken lay eggs even in absence of roosters? Otherwise how does "battery laying" work?
AFAIK battery laying uses a special breed of hens that don't require a rooster.
Interestingly, my parents had a lady duck for a while and she layed eggs -not too frequently- without a male duck.
Human females lay eggs in the absence of the male. They are just not laid in places one can generally locate them as easily as hens eggs etc. :mrgreen: (and they don't lend themselves to breakfast with soldiers..... ).
Quote from: Griffin NoName on January 08, 2008, 11:55:38 PM
Human females lay eggs in the absence of the male. They are just not laid in places one can generally locate them as easily as hens eggs etc. :mrgreen: (and they don't lend themselves to breakfast with soldiers..... ).
Well maybe not with
toast soldiers... :bed:
Going back to ducks--duck-egg pancakes = delicious.
Why is the central nervous system called central?
If there is a perfectly sensible argument, why have I never heard of a different type of (non-central) nervous system?
Quote from: Griffin NoName on March 07, 2008, 06:38:09 AM
Why is the central nervous system called central?
To distinguish it from the Autonomic Nervous System (http://en.wikipedia.org/wiki/Autonomous_nervous_system)
Quote
If there is a perfectly sensible argument, why have I never heard of a different type of (non-central) nervous system?
It's a medical geek thing.
Thinking a bit harder, another reason might be that there are well known diseases of the CNS (like Multiple Sclerosis), but ones of the ANS tend to be less well known and described in terms of the local dysfunction rather than as an ANS problem per se. Just a theory...
Quote from: beagle on March 07, 2008, 08:54:05 AM
Thinking a bit harder, another reason might be that there are well known diseases of the CNS (like Multiple Sclerosis), but ones of the ANS tend to be less well known and described in terms of the local dysfunction rather than as an ANS problem per se. Just a theory...
well as long as it's only a theory you know-- that's just a guess you know--- that's just something you made up so I'd believe is and go to hell.....
good try pup
(obviously you do know I am being wayyyyyyyy sarcastic -and at no extra charge either)
Once again in case anyone missed it--- Baby Pictures (http://www.youtube.com/watch?v=kmx1s8jlJP4)
I'm flattered. Who would have thought I'd join big C.D. in the ranks of those whose theories send you straight to the big bonfire.
There are the so-called triangular numbers. They get their name because they are the sum of the sequence of natural numbers becasue they form a triangle
mathematically spoken a trianular number is on that can be expressed as (http://upload.wikimedia.org/math/2/a/9/2a931844088c2528129eb061853b0327.png)
The number of the beast (666) is such a number.
Are there bigger ones of the kind that only consist of identical digits?
Is there a simple formula to find them?
There are no larger triangular numbers with identical digits less than 100000000 200010000 ~500000000. How high do you want to keep looking?
(I don't have a formula, but I do have logic & conditional formatting in Excel) :mrgreen:
Did you notice that 666 is the sum of numbers up to 36 (6*6) and is the sixth internally repetative triangular number (including 1, 3 and 6)?
I think it may be easy to tackle this problem from a statistical perspective - numbers with repeating digits become very statistically rare as the number of significant figures increases, and the gaps between triangular numbers become large.
Quote from: beagle on March 07, 2008, 08:54:05 AM
Thinking a bit harder, another reason might be that there are well known diseases of the CNS (like Multiple Sclerosis), but ones of the ANS tend to be less well known and described in terms of the local dysfunction rather than as an ANS problem per se. Just a theory...
One of the fields of carcinoid research...
Contemplating the Nasal.
When one has a head cold, why does it often (or in my own case always) affect one nostril only - one side builds up sneezes, runny, blocked... the other feels almost normal?
they(sinus cavities) toss a coin
whom ever gets tails gets the snot. :mrgreen:
sorry,
mine will begin on one side, usually, then progress to both sides with variances during the day, one side painfully blocked or copiously dripping the other dry and open, both completely blocked, both open- sometimes due to meds sometimes due to? -- I know I'm really in for it when I hurt, I don't always hurt with a cold, but when I begin with pain then I know something virulent and violent is about to hit me.
could it be that one side receives the virus that will cause the cold and the other does not and so that side will be more symptomatic?
Pure speculation: The sinuses get really bad when the exits are sealed and the slime production and swelling proceeds. With closed exits the virus/bacteria transfer to the other side could be blocked too.
On the other hand I had the experince as a child* that aphthae in the mouth tended to stay on one side too (with no side preferred). That would contradict the "blocked way" hypothesis.
If the sinus thing is always on the same side, there could eb anatomical reasons (as is the case with me)
*not the case anymore
The question is--how deviated is your septum?? That's part of it...
The other part of it is the Sinus Gods playing games with your head. :help:
I was told that your nostrils take turns being blocked up so you can at least semi-breathe (I guess God doesn't like mouth breathers). You're in for it if both gets blocked.
I've busted veins in my sinuses getting rid of blockage when sick or suffering allergies, though those were times I was ridiculously sick or had a really bad time with rag weed and pine.
Possibly I failed to give a vital clue.
The side that I get migraines never gets the cold. The side that gets the cold never gets the migraine.
Chatty wins this round !
http://en.wikipedia.org/wiki/Nasal_cycle
Even under normal conditions, one nostril tends to be blocked up. I think one notices it more with a cold since the blockage is complete.
Fantastic Aggie. Thanks.
Why is it more difficult to swallow pills with warm liquid than cold?
Because they start breaking down faster in warm liquid?
I noticed that the tongue tends to go back while sipping a hot beverage but I don't know the cause.
Wild, uninformed and baseless speculation: to prevent us from choking with our own blood. I noticed that the reaction is more marked when the stitches from my tonsillectomy came loose.
Why do they have standard doses for drugs?
Isn't giving a 6' 4" 15 stone man the same dose as a 4' 8" size 0 woman a bit bizarre ?
I am thinking in terms of bad reactions, ie. severe adverse reactions, rather than the killing the bugs aspect. And I am excluding drugs that are given by weight like chemotherapy.
Theoretically, a physician is supposed to modify the dose by the size of the patient.
Of course, in THEORY, doctors are all competent and caring...
I wist I could live in Theory. Everything works there.
Experience shows that giving patients not prepackaged doses but e.g. loose powder too often leads to accidents because people are too stupid to get the prescription dose right by themselves (and who has a precision balance at home anyway?). Even "Take one in the morning before breakfast , 2 at noon before lunch and 1.5 before going to sleep not eating anything afterwards" is too complicated for many*. Even the package insert is often far from precise these days. I remember older ones that gave instructions like "15 minutes before the next meal and at least 2 hours after the last. Keep a distance from drug XYZ of at least 1.5 hours or there could be bad mutual influnece". Newer ones drop all the numbers and I am clueless (especially about the ones that should work on the stomach, so a distance to the meal makes eimmediate sense).
*For liquid stuff dosing should be easier, if people were able to count to 20 or being able to tell a tea- from a table-spoon.
So like cars, amongst other discriminations, woman (and others) have been subjected to one size fits all (men) !
I wonder what my life would have been like with correct doses? And would the list of drugs I cannot take be empty?
And pre-packaged doses for S, M and L would not be too difficult - it might even be a revenue spinner for big Pharma.
My favourite package insert "keep out of the light" - it smacks of evil and secrecy. My chemo had to wear a little jacket during delivery into my veins so no one could see it. ;D
Chatty, can I join you in theory?
The antihypertensives the whole family takes are splittable into 3 parts and other drugs are of the "take x of these according to presription". My mother had once a type she had to take 20(!) each time (large pillbox for that). No problem to fine-tune the intake there ;).
As Swato says, getting people (especially old people) to take the right drugs in the right doses at the right times is notoriously difficult. For things like lowering blood pressure do you set the dose right for maximum effect, or do you set it so taking two by accident won't kill them?
To get the ideal dose you should probably weigh the same as the rat or beagle they tested it on, but their lives are not to be envied in other respects.
I love the dosages that are age and gender balanced, not realizing that a 55 year old X00 pound woman with extensive liver tumors is NOT a typical 55 year old woman.
Forget size. My liver's half non-functioning...
I love my new baby doctor-child (I'm old enough to be his mother, he's a child) who got a computer program that allows you to input all the variables and assess dosages that way. (It's in beta, it's not anywhere near perfect and the five pharmacy professors that wrote it will get an inquiry and call him [real time] for more specifics).
The 'keep from heat and light' ones are the ones I love. If I'm going anywhere and will be gone more than 24 hours, I have to carry an insulated lunch carrier with an ice pack and my spare octreotide. Theoretically, I'm OK for longer, but if I need a massive amount for some reason, this way I have it.
Sounds like there's a need for custom compounding of pills, combined with time-and-day marked blister-packs (the latter does exist) - i.e. real pharmacies rather than fast-food style pill dispensaries. ::)
Standard practice in Eastern traditional medicine BTW (everything is tailored specific to the patient's overall health, not the symptoms), although the bulk of the materials used do tend to result in a dose being a packet of what appears to be miniature rabbit dung, by the dozen.
Quote from: beagle on August 21, 2008, 01:58:45 PM
...........take the right drugs in the right doses at the right times is notoriously difficult.....
I think that's a separate argument. :o
along the lines of two wrongs don't make a right, although I've never really believed this can ALWAYS be true Quote from: Agujjim
.....time-and-day marked blister-packs (the latter does exist)
An EU moan (to cheer Beagle up): increasingly my pills come with the days of the week in more and more obscure languages ! Gone are the days when I can just pop a pill. I need a pile of dictionaries and a diary nowadays, and I still end up confused.
One of my friends (a tenured university professor, FWIW) experienced a series of psychotic breaks requiring ... mmm ... "voluntary" committals for undetermined amounts of time after each episode.
I was quite horrified to visit her on one of her "healed" trips home to find her trying to cut a a tiny, roundish anti-psychotic pill in half with a large, sharp knife, in order to follow dosage instructions. Oh yeah, she did that every time, no big deal to her...
:o
What's the Latin for Monseigneur ?
Literally: dominus meus (=my lord/master)
The vocative form of this is mi domine
It's not actually a title (as doctor,professor etc.) but a form of address (like mister)
Quote from: Griffin NoName on October 02, 2008, 01:03:39 PM
What's the Latin for Monseigneur ?
There you are, told you he'd know. If offering E the Monseigneur title doesn't do the trick you could consider offering him Droit de Seigneur instead.
That had occured to me. I have a simple mind.
Thanks Swato.
Well, if you can't keep these old traditions going in a monastery, where can you?
That droit needs a lot of excercise. Better stay with pets that do not require it (unless you need a diet of course)
I just encountered a math/geometry riddle I have not yet found the solution to:
A picture is to be hung on the wall (with the usual string method). For safety reasons there are two nails not just one.
But a malicious trickster draws the string in a way that the removal of any of the two nails will make the picture fall down.
How did he do it?
I only find solutions where the removal of one of the nails causes the effect but the removal of the other does not.
Hint: van Kampen's theorem.
Bigger hint (http://jedidiah.stuff.gen.nz/link_problem.pdf)
Next question. How many mathematicians does it take to f*** up hanging a picture?
Thank you.
And the answer to your question is 'zero'.
It does not take a mathematician to f*** it up :mrgreen:
Can't take much credit I'm afraid. You would have waited a very very long time for me to have come up with the proof after 30 years gap from even elementary topology, but I could remember the right mathematical hammer to use for these particular nails and Messieurs Google and Live Search took over from then.
I trust the author of the solution got the Mrs Joyful Prize for Raffia Work based on page 14 onwards ;) ;)
I'm sure there are prizes for a good knowledge of ropes and knots; probably not awarded by St Custard's School though.
(http://www.fellowes.com/gb/images/product/large/8037401.jpg)
This calls itself a Professional Series Flat Panel Workstation - which isn't what I'd call it personally given my brain confuses that with some odd version of Windows NT etc. LOL!
It is utterly totally the thing I need (for a different purpose) but it is just a few cms too wide for what I would need to sit it on, which is not a desk.
Having eliminated all similar products (and therefore "descriptions") by googling - riser, stand, monitor, printer, CRT, raiser, desk, shelf, free standing, plinth, bridge, platform, over, under, wood, acrylic, ergonomic +++++ etc etc - and not finding anything that remotely resembles it - at least in it's full glory, the easy question is:
What this looks like to me is a mini-coffee table. However, one would not want expect the world to call this a mini-coffee table as people would not think of having mini-coffee tables on top of their their desks (although I think it is a good idea).
So what is a proper name for it?
sorry, only vaguely science related ;)
Computer table/stand?
I was too lazy to read all 16 pages, but the first easy question made me want to ask: Why do things get smaller when they get further away?
Because the perceived height at the eye is proportional to the angle between a ray from the top of the object to the eye and a ray from the bottom of the object to the eye. Close, big objects can be almost 180 degrees but when far enough away will drop down to (eventually) 0 degrees. Width works the same way.
Looking up a description of perspective (http://en.wikipedia.org/wiki/Perspective_(graphical)) will probably give the best insight into how it works (and how long it took artists to work out how it works :mrgreen: ).
P.S., Good to see you back.
Aren't these supposed to be for children to understand?!
But the angle is not strictly proportional to the distance necessarily. There is that classic math problem a professor invented beacsue his students complained about lack of applicability of analysis:
A student walks behind a pretty short-skirted girl. The lower end of the skirt is at 60 cm above ground and his eyes are at 170 cm above ground. At what distance can the student see the legs under the largest angle? For the moralists: the answer is not zero. And for the hopeful student: it is not infinite ;)
That's actually quite tricky until you find the right way to solve it (then it's very easy).
I suppose the sledgehammer approach is finding the turning points of
(pi/2)-ATAN(distance/170)-ATAN(110/distance)
by differentiating WRT distance?
Is the easier one to recognize that the maximum of the required angle will occur for the minimum of the sum of the above two ATANed angles, and that in the first quadrant that will occur at the distance giving the minimum of the tan of the sum of the two angles, and then use the trigonometric tan(A+B) identity to eliminate most of the nastiness before differentiation to find the minima?
Anywhere near the right track?
The easiest solution I found is indeed minimizing the sum of the adjacent angles. I think I did it over the sin not the tan but I did not check. :1stprize: (wasn't there a thumbs-up smiley?)
Has your professor been locked up by the political correctness police yet? Did "I was just measuring for a trigonometry question" cut it as an excuse?
Who was the famous mathematician who was horrified to find his work actually had a use? G.H. Hardy probably I suppose.
It was not my professor, I got that anecdote from a book.
About the shame of applicability I think it was somebody in connection with matrix calculations.
Ok, new 'easy' question: Why is the moon perceived as bigger when it is close to the horizon than when it is on the zenith where it is likely to be closer to earth?
I can't believe you've not heard of the oculomotor micropsia/macropsia theory (http://en.wikipedia.org/wiki/Moon_illusion) . Don't they teach anything in U.S./Colombian High School? ;).
(OK. So I bunked off school that day too). And according to this (http://www.lhup.edu/~dsimanek/3d/moonillu.htm) it doesn't explain it anyway. The Beagle solution is to howl at it until it goes away.
Quote wiki - For over 100 years, research on the Moon illusion has been conducted by vision scientists who invariably have been psychologists
Quote wiki - It must also be kept in mind that people differ in how they experience the illusion (and some have no Moon illusion)
Begs another Easy Question:
Where is the entry in the DSM for this disease ? (Absence of Moon Illusion)
we always knew Beagle was barking mad
Quote from: Griffin NoName on January 13, 2009, 05:40:22 PM
we always knew Beagle was barking mad
I'm told one is judged by the company one keeps. And why are we whispering?
Question from an area we did not cover yet:
Is there a linguistic/etymological connection between fascination and fascism or is the word similarity coincidental?
I know that the latter is derived from the bundle of rods (fasces) that was part of the insignia of the Roman lictors
Exhaustive research (Ok, Google) suggests that the root of fascination is "An attractive binding secret", so maybe it's the ribbon holding the rods together that is significant.
And what about fashion? Is that about wearing ribbons? ;) ;)
The aerial cable to the TV roof aerial is unplugged. IE. there is no connection to the roof aerial at present.
My TV, without the aerial cable plugged into it, has the expected fuzzy pic and sounds.
My TV with the aerial cable plugged into it, has good pic and sound.
How can this be, when the cable is not actually connected to the aerial?
1 You're not plugged into the external aerial you think you are.
2 You have such a good TV/signal strength area that any old bit of wire out the back of the telly will work. Clue, can you touch Crystal Palace or Alexandra Palace from your balcony?
3 Whoever told you the roof aerial was unplugged lied (See under Miss Marple "You shouldn't believe what people say, it's very dangerous. I never have for years").
4 Quantum effect. Can you be on your roof and in your living room at the same time? I thought not; One of your measurements is assumed.
5 We're all in some big computer simulation and you've spotted the trivial coding error that reveals it. Panic.
Do any of your answers come with a guarantee?
Did any of your questions come with a payment?
They may have done if there was a guaranteed answer ;D
Why does burning a candle when smoking a cigarette make the smell/smoke more toerlable for non-smokers?
Same reason a candle or match is the loo helps with that odor. It burns the gases that are objectionable and cause the sensation of 'stink'. Minus those gases in the air, less smell!!
...it also seems to remove the smoke....how?
It burns it...
Smoke is a product of incomplete combustion. Burning it again, in the candle flame, produces much more complete combustion. Even though the candle flame does incomplete combustion on the carbon in the wax...
Try beeswax then.... higher combustion temperature, nice odour.
I always thought the trick was to smoke the wicked stick cancer over the candle, but friends tell me you just need to be sort of near a candle..... so following Mero's statement, how does the smoke get attracted to the candle from a distance in order to be combusted? Intelligent Smoke?
The smoke is relatively heavy so tends to hang in mid-air. The candle flame is a convection engine and generates air currents circulating in the room. (This is why scented candles scent the whole room). :)
Quote from: The Meromorph on March 26, 2009, 12:54:58 AM
(This is why scented candles scent the whole room). :)
Unfortunately not the cheap ones ;) ;)
My finger got squashed in a door about two months ago. It was really bad and nasty cuts on both sides of the finger. Yuk mangled and lots of blood and deep cuts. They cleaned it up and so on but it didn't really healing propely. After about a month I realised there were splinters from the door frame in the cuts but very deep inside. Because I was too ill to go anywhere I did nothing about it (they were too deep for me to fish out) except swab it with loads of antiseptic.
Eventually it all started healing over but continued to hurt if I touched the points where the splinters were underneath.
Now it is completely healed and doesn't seem to hurt.
Today I told my GP about it expecting to be told to forget it. Instead I've been prescribed Magnesium Sulphate paste to draw the splinters out. I was surprised as it is completely healed over so this seems like magic. Reading up on the internet it seems Magnesium Sulphate paste can even be used to extract pace-makers.
Is this really true?
How?
Will my finger start hurting again?
Used it to draw out a broken-off half toothpick in my toe years ago, and it didn't hurt, just sorta popped up and I pulled it out.
(It was also used to pull broom handle splinters out of my back 30+ years after the fact, and didn't hurt then either, only itched.)
It's magic. There are little gremlins, of 2 kinds, the Mags and the Sulps, and they take turns sneaking the splinters past the nerve endings. They're really good at sneaking stuff, so you never know that it MIGHT have hurt, but didn't.
Isn't science fascinating?
That just amazes me !! (hmmm need to rethink Science and G-d :irony:)
How long does it take? Broad brush - unless you are magic at counting days :giggle:
Depends on the 'depth' of the stuff...how long it has been there, etc.
I don't really remember anymore, as it has bees several years. (I've slept since then and I need retraining every time...)
No deeper than one finger side - there are actually two - one on each side of the finger - and I was putting the MS on both til I realised that would attract them both to both sides and cancel itself out :giggle:
A question prompted by current TV news:
Why is advice given to go to one's GP surgery if suffering from symptoms of potential epidemic or pandemic illnesses etc.?
(at least this is always the advice given in the UK).
It makes no sense whatsoever to me to deliberately gather suspect people in waiting rooms full of other people who already have other illnesses etc.
Of course when we reach Alert Level Six we are told to stay home and die, which seems sensible.
Actually, if it were up to me, I'd tell anyone who may have any illness to avoid their GPs surgery altogether !
Please can someone provide the easy answer to this ;D
I think the advice for this lot is to ring up and wait for somebody to throw some Tamiflu tied to a brick at you from the end of the drive.
And don't eat fajitas, drink, smoke or otherwise have fun (but that's standard NHS boilerplate advice). And under no circumstances do an internet search for Cytokine Storm. Unless you're over 50.
I just hope they use hand sanitiser on the boxes containing the Tamiflu.
Take several small and several medium size trials (randomised, blinded control group, ie pukka). They all have clear +ve outcomes (apparently siginificant although we know it isn't really as only large trials can have significant results).
Take large trials of the same thing - same rigour etc. This shows clearly there is no +ve outcome.
I understand the "science" behind why "large" is a total must but despite my now ancient qualification in statistics, I can't think how to express - in plain english using simplistic common terminology - why/how the +ve slides down to being non-significant. And for example, how would one answer a question such as : at what point does the sample size become "large enough" without using words that "the man in the street" would not need explaining? (Remember "the man in the street" does not know what the difference between mean and average is and actualy won't have heard of the mean as a word in any case; would probably understand probable, but never heard of probability.. etc).
YES I have been watching a documentary about homeopathy. And isn't it strange that the larger (sample size) the trials the less effective homeopathy is shown to be, whereas the larger the "dilution" of the remedy the more effective it is.
:irony:
Ok, I don't know if this really classify as an 'easy' question or if it should be under pets.
Why feeding animals brings a sense of comfort? Specific examples are people feeding wild pigeons, ducks, cats, etc. In my specific case, I do feel comfort and peace when my birds eat from my hand, plate, or in the dinning table (as opposed when they are eating their seeds on their cage).
Quote from: Sibling Zono (anon1mat0) on June 08, 2009, 06:33:37 PM
Ok, I don't know if this really classify as an 'easy' question or if it should be under pets.
Why feeding animals brings a sense of comfort? Specific examples are people feeding wild pigeons, ducks, cats, etc. In my specific case, I do feel comfort and peace when my birds eat from my hand, plate, or in the dinning table (as opposed when they are eating their seeds on their cage).
its because you know that secretly you are just fattening them up for the cooking pot! :mrgreen:
More of a tech-question.
Does anybody here have an idea how to construct a purely mechanical XOR gate (preferably without springs involved).
It should function in the way of the sketch seen below. Alternatively the input pins could also rotate into position* instead of moving forward and back and the output pin could be at right angles to the input pins.
*pin wheel, cogwheel
Remind me if you don't get an answer soon! Need to puzzle this out. Looks reasonable. Could be done in theory with a balance and I think I can proceed along those lines.
I know a partial solution but that would require an AND gate to be put behind and I did not solve that either.
Is there a limit to complexity and/or type of moving parts? My first thought was sliding levers allowing a drop-through channel (to solve the problem, not fit the model).
I'm a junk-drawer tinkerer so I generally don't bother with anything that can't be done with simple tools and scrap materials.
Actually, any hints on what the output pin requirements are (needs to exert force, or simply needs to hang out there?) would help. Also, is a horizontal configuration necessary?
Output pin should exert moderate force at least enough to trigger a stronger force exerter.
It should also work, if the parts are rather crude. If the whole thing would be 2x2 inches then 1 mm tolerance should still be sufficient. Input and output should not be on the same side, otherwise it doesn't matter much. No requirement for it to work in more than one position, i.e. it can use the direction of gravity as a part of its working mechanism (e.g. a weight that keeps Output=0 when the input pins are not engaged).
Toilet paper in the UK consists of two layers of paper. Why don't they make it from one thicker layer?
Otherwhere it's even 3 or more layers.
Quote from: Griffin NoName on July 30, 2009, 12:03:59 PM
Toilet paper in the UK consists of two layers of paper. Why don't they make it from one thicker layer?
This may require some experimentation: A thicker paper is used in kitchen paper towels and the the texture is similar.
Erm... try using it as toilet paper and you should get your answer.
:o
No, kitchen paper is a different texture - coarser - and thicker than two sheets of toilet paper.
Actually, toilet paper in Turkey is more like kitchen paper..... but then they don't flush it.
And some of you siblings wonder why others disappear for weeks at a time...
;)
Quote from: Griffin NoName on July 30, 2009, 11:38:03 PM
No, kitchen paper is a different texture - coarser - and thicker than two sheets of toilet paper.
Actually, toilet paper in Turkey is more like kitchen paper..... but then they don't flush it.
Ever used toilet paper made in the Eastern Bloc? VEB Sandpap(i)er.
Quote from: pieces o nine on July 31, 2009, 05:41:23 AM
And some of you siblings wonder why others disappear for weeks at a time...
;)
:ROFL:
Nobody is forced to read this thread ;D :D :mrgreen: ;) ;)
we must ensure the ability to enquire into all aspects of life on our planet ::) :oQuote from: Swatopluk on July 31, 2009, 09:01:27 AM
Quote from: Griffin NoName on July 30, 2009, 11:38:03 PM
No, kitchen paper is a different texture - coarser - and thicker than two sheets of toilet paper.
Actually, toilet paper in Turkey is more like kitchen paper..... but then they don't flush it.
Ever used toilet paper made in the Eastern Bloc? VEB Sandpap(i)er.
Hmm. Thinking further on this, the countries I have been to that have the coarser papers also have single layer papers. So perhaps combinging layers causes a corsening? Perhaps something to do with the fibres?
Standard: the more layers, the more luxurious. I think only the US (and maybe Japan) go up to 4 layers.
This site may be of use:
http://encyclopedia.toiletpaperworld.com/
What's wrong with using the Sears Catalogue, like our ancestors? (they had the non-glossy version);)
(not sure if this was as popular with Americans, but y'all DO know why the Farmer's Almanac has a hole punched in the corner, right?)
I think that TP has to balance strength with softness; like with wood products, you can get away with using softer materials if you layer them up (softwood plywood), but to achieve the same strength for the same thickness in a single layer, you need to have good strong stock. Softness is increased in the multi-layers because of the airspace between layers, I think, and also because weaker fibres can be used.
I grew up using an industrial-supply grade single-layer. Paper towels seem luxurious by comparison. I recently looked at the economics of it and convinced my parents that cheap retail double-ply brands were actually a comparable deal (one tends to use more squares of a single-ply per use, so you can't price it on a sheet-to-sheet basis) and much less flaying. (Swato, I'm pretty sure that the grade I grew up on was comparable to Eastern Bloc TP - similar to newsprint, but thinner and more porous).
Double rolls (~400 sheets) of adequate 2-ply go for about $0.50 Canadian here when bought in semi-bulk (36 rolls).
Hypothesis: more layers mean each layer is thinner therefore easier to leave particles.
I took a bit and started to move my fingers against each other with the paper in the middle and it didn't took long to start leaving tiny bits of paper on my fingers. It is possible that a thinner ply works in a way that may resemble a lubricant, hence feeling softer.
Suggests that one will have more willknots from high-ply TP...
When dealing with industrial water conditioning, one classifies water conditions (hardness, pH, concentrations of certain dissolved elements) as scaling (leaves deposits) or corrosive (removes deposits and/or the original material of the processing equipment). I can confirm that single-ply industrial tends towards the latter. :P
Hmm, the Toadfish have historically stayed out of the toilet; are we unacceptably breaking any taboos? Slap me with a trout if I cross any lines, because I can honestly state that nothing here is outside of what I'd be comfortable discussing at the breakfast-table (and would extend that back two generations on my mother's side, if my maternal grandparents were still living). ;D
Let me go on record as saying it was high time we brought up the subject of toilet paper texture, thickness, price and nationality here. And Turkish potties. What indeed is a monastery for, if not this sort of winsome conversation?
Being a New Englander, I tend to prefer one-ply Scot tissue, in white only. No frou-frou puffy TP for me, nosirree! It has to be strong and straightforward and no nonsense. And none of those little crocheted potty dolls for me, either! When I do my business, I mean business.
Did I say that out loud?!
:blush:
Is it always good to have an enquiring mind?
The first in-depth study on different 'ass-wipes' can be found in Rabelais' Gargantua. Whether he actually conducted the experimental studies is in doubt though. ;)
I suspect the price of a goose has risen substantially in the past few centuries. ;) ;) ;)
and what do you wipe up all the goose shit with?
The chapter in question is priceless. :mrgreen:
The "TP" we used to get issued in our ration packs was smooth, glossy and best used as tracing paper for making maps.
The trooper who remembered to heat seal a roll of Andrex in a binbag was everybody's bestest friend....
We had tracing paper at home for years after everyone else had changed to softie cos my Dad didn't believe in pandering to our requests for relief. :o
I recalled one tiny detail about toilet paper that hasn't been mentioned yet: the reason for its thinness is that it must dissolve with water to prevent pipe clogging. Multi-ply is just a way to have thinner paper while at the same time conforming with the standard.
A good point and I am relieved <groan> to see you are still applying your mind to this topic. :mrgreen:
In the first flush of enthusiasm for this topic, readers were on a roll with responses. Now it has passed and interest is petering out...
Thank heaven.
<groan>
Hey, even the Economist has succeeded in dragging a bit of toilet humour over three editions (see Letters section for the last two weeks). ;)
Changing the subject, I have a question about seasonal flu (and peaks for swine flu).
In England, seasonal flu occurs in the winter. Winter is cold and dismal. The sun is a long way away.
In Australia (Sydney etc) seasonal flu occurs in the winter. Winter is not very cold and dismal but more like a mild English Summer.
Why do we get "seasonal" flu in England? If it is anything to do with the weather, and basing expectation on the Australian conditions, we might expect to get flu pretty much all the time, except in heat waves.
Am I being very stupid here?
Hmmm.... reputedly it has to do with humidity, but you are right - while it makes sense on a relative basis (winter being the most likely time to catch it, because conditions are most condusive to spreading it), it doesn't add up on an absolute level (x set of conditions are adequate to effectively spread it). To continue your example, Calgary summers (especially June/July) are like an English winter - wet, cold and dismal with occasional snow. Our winters are sunny and very low humidity (and bloody cold!).
I think that the relative factor is more to do with people spending time indoors and in large groups - especially school children (hmm.... when's summer break in Oz?).
I always heard that frequent changes in temperature make the body more susceptible to catch the flu. In winter people frequently is switching between hot clothes to a cold environment outside to a warm environment inside, etc. You could argue that in the summer is the same but backwards (hot outside, cool inside) but a warmer enclosed environment is a much better vector.
I think the flu has a rather narrow temperature window outside of which it does not function well. So outside the window it has to be transmitted directly* while inside it can stay alive outside the host for a time an thus be transmitted indirectly.
I think the main flu season is in the change periods from winter** to summer and the other way around when the human immune system is under stress.
The common cold is pretty unkwnon in arctic and antarctic conditions but people coming from those regions into temperate zones almost immediately catch it. In this case it is because the immune system has fallen asleep due to lack of work.
*eased by many people sticking close together
**also defined as the season where people try to heat up their dwellings to levels they thought intolerably warm in summer :mrgreen:
Quote from: Swatopluk on September 17, 2009, 03:26:13 PM
**also defined as the season where people try to heat up their dwellings to levels they thought intolerably warm in summer :mrgreen:
LOL, being from a cold climate with hot summers (back home) I've noticed the opposite - nobody would suffer through air-con temperatures in the winter, but think it's great in the summer (and are usually wearing less clothing to boot).
So it's to do with the immune system not coping with "changes" in temperature?
But this still doesn't make sense as far as UK goes as we get big changes all the time.
I think the virus likes moist air and is damaged rapidly by ultra-violet light. A dark, moist, recirculated air environment makes it as happy as a pig in ... a sty.
Read recently that some company is trying to interest aircraft makers in installing UV virus killers in the ventillation systems. Think it takes about 8 of them at £10000 each for a normalish commercial aircraft.
I hadn't heard the outside temperature change argument before. Certainly I'd read that the rise in internal body temperature during a fever is a general immune response to slow down subverted cell virus factory production while the correct antibody production is ramped up by (I think) clonal B cells.
The sore throat is an effect of the subverted cells being destroyed by generic stampers (I forget the proper name). As I understand it, artificially bringing body temperature down too soon may make you feel better but can increase the virus load.
Quote from: beagle on September 17, 2009, 08:56:41 PM
I think the virus likes moist air and is damaged rapidly by ultra-violet light. A dark, moist, recirculated air environment makes it as happy as a pig in ... a sty.
Doesn't jive with Calgary winters - we are dehydrating and largely sunny in the winters. OTOH, the temperature-change theory does - I've personally seen it go from -25 C at midnight to +20 C at noon. :o
Atmospheric pressure changes are hell for migraine sufferers here (due to Chinook winds).
Maybe, but the virus transmission probably occurs indoors, in heavily recycled air under not natural wavelength balanced artificial light.
I'll consult my betters at work on this one , and report back if I understand the explanation (big if).
edit:
P.S. The schools are shut during summer. A thousand people with little immunity in an enclosed space is a great environment for our little friends. Possibly King Herod was an underrated epidemiologist.
Quote from: beagle on September 17, 2009, 09:09:16 PM
Maybe, but the virus transmission probably occurs indoors, in heavily recycled air under not natural wavelength balanced artificial light.
True enough - and even though we get sun in the winter, days are pathetically short and the angle of incidence is low. However, considering that many, many people are office-bound these days, I'm not convinced that indoor air conditions vary significantly with the seasons (drier with air-con than with heat in some climates).
Children as vectors is very likely, although I think it gets passed in parallel (parents in offices handing off to children passing back to other childrens' parents.
Apparently the Intelligent Designer re-used code (http://www.reuters.com/article/scienceNews/idUSN0228175320080302?feedType=RSS&feedName=scienceNews&sp=true) from M&Ms due to project over-run or something.
QuoteIn cold temperatures, the hard lipid shell might withstand certain detergents, making it more difficult to wash the virus off of hands and surfaces.
The simple answer: drink plenty of detergent.
I still don't get why winters which are at diferent mean temperatures have the same result. Unless the temperature in our respiratory systems is the same degree of coldness in summers whatever the outside temperature.
Meanwhile I can hear the man downstairs sneezing vigorously. If I disappear you'll know why.
QuoteThe simple answer: drink plenty of detergent.
I was close to saying the same but was unsure whether it was appropriate.
Seriously, detergents can be used to blow up cells (only ionic detergents though, I think). But I am not sure, if viruses are also affected.
Quote from: Griffin NoName on September 18, 2009, 02:30:39 PM
I still don't get why winters which are at diferent mean temperatures have the same result. Unless the temperature in our respiratory systems is the same degree of coldness in summers whatever the outside temperature.
Maybe because viruses usually exist in the population in a steady-state for some time, but are most likely to break through into explosive growth when the environment is best locally.
I'm not totally convinced by my argument here either.
I think it must have something to do with relativity.
Why do stories end with "......and they lived happily ever after" ?
Because that's a boring ending (but gratifying) and nobody cares to hear any further details (calms down the little ones, few additional questions need to be answered). ;)
Might as well ask why meals must be ended with disgustingly sweet foods (dessert) - same concept. I prefer that my mouth remains redolent with the spice and pungency of the main course, although I don't mind taking a little fruit, provided it's exciting enough to tickle my tongue.
IMHO dessert is better at a distance between meals, and best in the afternoon with a dark coffee, or in the evening during a study session (in my uni days). Provides a nice little burst of sugar to get the brain moving, without the belly already in overload mode.
Quote from: Griffin NoName on September 28, 2009, 02:42:11 AM
Why do stories end with "......and they lived happily ever after" ?
It's to do with global warming. As Agujjim implies, if you told the little sprogs the truth in their bedtime stories you'd have to leave the lights on all night and buy bigger teddy bears. It's the junior form of the Treasury's Economic Forecast.
The reason for dessert is that no one would eat their cabbage without some sort of incentive.
The German version is not as rosy.
...and if they have not died (yet) then they are still alive today.
No unsupported claims about happiness there
Quote from: beagle on September 28, 2009, 07:38:41 AM
The reason for dessert is that no one would eat their cabbage without some sort of incentive.
Nobody who insists on eating it boiled, anyways. ::)
Cultures who traditionally season it up and/or ferment it seem to need less motivating. I blame factory farming (i.e. tasteless produce) plus Puritanical preparatory methods for the North American shift from meat-and-two-veg to meat-and-potatoes (although, if one eats chips, ketchup is a vegetable according to Reagan).
The wife especially is a bit mystified by the "vegetables are to be endured but not enjoyed" mindset, because they know how to prepare 'em back home:
(http://upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Korea-Seoul-Sosim-Vegetarian_restaurant-01.jpg/800px-Korea-Seoul-Sosim-Vegetarian_restaurant-01.jpg)
Quote from: Agujjim on September 28, 2009, 03:37:56 PM
(although, if one eats chips, ketchup is a vegetable according to Reagan).
Not as way out as it seems. Real tomato ketchup is stashed full of lycopenes which are tick v.g. for you, unlike lycanthropes, which aren't. Science is so confusing.
Ayuh, tomatoes are the the one exception to the "don't overcook your veggies" rule, but the tomato-to-sugar ratio is still dismally low.
...and it's skin isn't the best thing for you either.
Quote from: Swatopluk on November 15, 2006, 03:23:59 PM
How can you show that the Earth is roughly spherical?
But is it? It could also be a convex disk. I mean, if we're trying to poke holes in common knowledge.
A convex disk would satisfy pretty much all
observable facts about the Earth. For example, the shadow cast on the moon would still be the same, ships leaving port would still seem to "sink" as they approached the horizon (to an observer on land), the sun would still rise and set as the disk rotated like a coin spinning on a table, etc.
Of course, you'd have to assume that reaching an edge would put you back to the opposite edge, like in the old Pac Man game, but we are asked to believe sillier things every day, right?
Quote from: Swatopluk on September 28, 2009, 08:19:01 AM
The German version is not as rosy.
...and if they have not died (yet) then they are still alive today.
No unsupported claims about happiness there
I read a lot of the original fairy tales growing up (and have recently taken to collecting the Color Fairy Tale Books), and I liked that ending better than "happily ever after." But I suppose it depends on the individual story, though.
Quote from: Zan on September 29, 2009, 04:51:56 AM
Quote from: Swatopluk on November 15, 2006, 03:23:59 PM
How can you show that the Earth is roughly spherical?
But is it? It could also be a convex disk. I mean, if we're trying to poke holes in common knowledge.
A convex disk would satisfy pretty much all observable facts about the Earth.
I don't want to be a party pooper but...
How about the view from orbiting spacecraft?
Also the way things fell to the ground would be at a strange angle near the edges of the disk.
Besides, I've been to Norwich. If the edge of the World was going to be anywhere it would be there, and apart from the odd dragon, stuff worked as expected.
Welcome to the site by the way.
Spacecraft don't count. Too few people that could reliably testify, and the same organisations that spread the round earth myth choose the people allowed in space.
And don't forget the possibility that the laws of optics are anisotropic.
As for the dropping paths of objects, what tells you that the density of the disc is the same everywhere. If the mass distribution is right, there should be no problem.
If the target population of this question were inclined to listen to reason a more definitive way would be the use of Foucault's Pendulum or even better, a gyroscope in different latitudes.
Quote from: Sibling Zono (anon1mat0) on September 29, 2009, 02:16:30 PM
If the target population of this question were inclined to listen to reason a more definitive way would be the use of Foucault's Pendulum or even better, a gyroscope in different latitudes.
But on a convex surface, assuming gravity operates from where the center of a sphere
would be, those methods would lead you to believe that the Earth is spherical. We can measure gravity, but we still have no idea how it works, I'm not sure we can rely on this method.
Quote from: beagle on September 29, 2009, 07:55:59 AM
Quote from: Zan on September 29, 2009, 04:51:56 AM
Quote from: Swatopluk on November 15, 2006, 03:23:59 PM
How can you show that the Earth is roughly spherical?
But is it? It could also be a convex disk. I mean, if we're trying to poke holes in common knowledge.
A convex disk would satisfy pretty much all observable facts about the Earth.
I don't want to be a party pooper but...
How about the view from orbiting spacecraft?
Also the way things fell to the ground would be at a strange angle near the edges of the disk.
Besides, I've been to Norwich. If the edge of the World was going to be anywhere it would be there, and apart from the odd dragon, stuff worked as expected.
Welcome to the site by the way.
1. Thanks for the welcome.
2. The "moon landing was a hoax" crowd wouldn't buy that argument (and I must say, it was awfully nice of Russia not to bust out the US Government's claim by using radar to NOT see the Apollo spacecraft). Also, the small number of people who have actually been in space would be easy to bribe or threaten into compliance, assuming there was a reason to do so (the physics lobby is the most vicious of all Washington power groups, I am told. They make Wackenhutt look like the Mothers March Against Dyspepsia).
Thanks for the warning about the physicists. I always knew those people were weird.
They're the worst. When they're not hanging around the science fiction sections of used bookstores trying to look menacing, they're out oppressing Christian Conservatives with their "science" and their "reality" and insisting that schoolchildren get taught "heliocentrism" and other rubbish.
Quote from: beagle on September 29, 2009, 04:37:11 PM
Thanks for the warning about the physicists. I always knew those people were weird.
Quote from: Zan on September 29, 2009, 02:55:47 PM
Quote from: Sibling Zono (anon1mat0) on September 29, 2009, 02:16:30 PM
If the target population of this question were inclined to listen to reason a more definitive way would be the use of Foucault's Pendulum or even better, a gyroscope in different latitudes.
But on a convex surface, assuming gravity operates from where the center of a sphere would be, those methods would lead you to believe that the Earth is spherical. We can measure gravity, but we still have no idea how it works, I'm not sure we can rely on this method.
Oh, but you can: pack the 'skeptics' in a boat going out from Iceland to Cabo de Hornos and make periodic measurements. The readings would suggest a
too convex Earth, almost spherical... ;)
Quote from: Sibling Zono (anon1mat0) on September 29, 2009, 05:13:23 PM
Quote from: Zan on September 29, 2009, 02:55:47 PM
Quote from: Sibling Zono (anon1mat0) on September 29, 2009, 02:16:30 PM
If the target population of this question were inclined to listen to reason a more definitive way would be the use of Foucault's Pendulum or even better, a gyroscope in different latitudes.
But on a convex surface, assuming gravity operates from where the center of a sphere would be, those methods would lead you to believe that the Earth is spherical. We can measure gravity, but we still have no idea how it works, I'm not sure we can rely on this method.
Oh, but you can: pack the 'skeptics' in a boat going out from Iceland to Cabo de Hornos and make periodic measurements. The readings would suggest a too convex Earth, almost spherical... ;)
Well, okay, but I insist on choosing the boat. After all, there's no need for people like that to
return from their mission, given that they wouldn't change their opinion anyway...plus, it would be a just punishment for ruining
Omni magazine with their silliness, back in the 80s.
It also occurs to me that a carrot-shaped Earth with the people living on the "top" would work, if you're willing to abandon heliocentrism.
We tried sending all the strange people off on a boat once before. It didn't work out quite as planned.
Quote from: beagle on September 29, 2009, 05:24:28 PM
We tried sending all the strange people off on a boat once before. It didn't work out quite as planned.
And don't think we haven't noticed. What's really funny about Fat City is that many Americans think Fat City won the revolutionary war...while, in reality, England spent 200 years getting rid of their religious crazies (to wit, the Puritans), and then left after being "defeated" at Yorktown.
Now we have things like the Orwellian-named "Liberty University" and Robert Tilton. We'd get revenge, but we're too busy trying to keep the nutjobs from telling us how we can live.
(Note: The above does not reflect my opinion on Christians in general, of course. Most Christians I now are very good people, and cause me no trouble at all.)
Quote from: beagle on September 29, 2009, 07:55:59 AM
Besides, I've been to Norwich. If the edge of the World was going to be anywhere it would be there, and apart from the odd dragon, stuff worked as expected.
I always thought it would be Grimsby.
Has anyone ever considered that the earth magnified from space must look like our commonly depicted viruses - what with lots of people sticking out from its surface?
Quote from: Griffin NoName on September 29, 2009, 08:19:43 PM
Quote from: beagle on September 29, 2009, 07:55:59 AM
Besides, I've been to Norwich. If the edge of the World was going to be anywhere it would be there, and apart from the odd dragon, stuff worked as expected.
I always thought it would be Grimsby.
Has anyone ever considered that the earth magnified from space must look like our commonly depicted viruses - what with lots of people sticking out from its surface?
So we're all part of one huge herpes virus?
That explains more things than I care to think about.
edited for endqoute ~Griffin
I forget the details of which sci-fi story, but from space aren't we just parasites that infest cars. Some friendly aliens might help the cars with pest control.
Quote from: beagle on September 30, 2009, 08:01:13 PM
I forget the details of which sci-fi story, but from space aren't we just parasites that infest cars. Some friendly aliens might help the cars with pest control.
Optimist.
When does one use the -one and when the -body form?
(anyone/anybody, someone/somebody, noone/nobody)
In colloquial usage, I don`t think there`s much of a diference. The -one form tends to be considered more proper / formal I think, but I can't think of an offhand example of one form being completely inappropriate. ???
I think I read about it recently but have completely forgotten the actual content.
Googling anybody anyone difference yields 16 Million hits !!!
An interesting proposal is:
Quote
Both are singular pronouns, and use anyone when you are suggesting a person in a known group, as in, "Has anyone in this room been hunting lately?" And anybody when you are unaware of the group, as in "Has anybody ever gone thirty days without food and lived?"
Quote from: Swatopluk on October 22, 2009, 02:00:59 PM
An interesting proposal is:
Quote
Both are singular pronouns, and use anyone when you are suggesting a person in a known group, as in, "Has anyone in this room been hunting lately?" And anybody when you are unaware of the group, as in "Has anybody ever gone thirty days without food and lived?"
I think it works better the other way round !
Agree with Griffin - and if it's in a present group I'd insert 'here' as well for precision, although it's not strictly necessary.
I tend to think -one should be used in the same context / tone of writing that one would use 'one', and -body used when you'd use 'you' instead.
hope that makes sense
Overall, I think it's a minor point. -body is less formal, so I'd stick with -one in polite / formal writing, but there's no reason to avoid it in colloquial use.
You mean in the sense of "Could somebody close the door please?" as opposed to "Could anyone defeat that dragon?" ;)
Precicely. Even if I'm not sure which part of the post (or which post) you are referencing. ;)
When they announce 12 million viewers watched "How to Ruin Your Best Friend's Birthday"* on TV last night, how do they know it was 12 million, switched on, tuned in, and actively watching?
They don't. What they do is to place some boxes in a number of households with certain known statistic references and from their viewing patterns they infer a number.
It is suggested that Tivo and other digital boxes actually do the counting in a more global way, and it is expected that as more digital distribution happens and more TVs are plugged to the internet the statistics will be closer to reality.
Provided that users check one of those opt-in options. :P
---
As I walked in airports this past two days I noticed that servicemen/women had a mirror image of the flag on their shoulders, does any one know why?
Quote from: Sibling Zono (anon1mat0) on November 14, 2009, 01:04:12 AM
As I walked in airports this past two days I noticed that servicemen/women had a mirror image of the flag on their shoulders, does any one know why?
To confuse any passing aliens?
Thanks for the easy answer on the 12 million.
Usually mirror images are used, so they can be read when seen in the mirror. For example on ambulance cars. If you see the readable word 'ambulance' in your rear mirror, then you know to make room. If it was printed the normal way, you'd be seeing only the less readable mirror image. But why flags on uniforms should be mirrored, I don't know. For most flags it wouldn't actually matter :mrgreen:.
---
A mathematical/physics question probably only proving that I am out of school dar to long:
If one would drill a shaft from pole to pole, keep it open (and cool) and remove the air in it, then dropped an object into it.
How could one calculate the time it would need to fall down the core and what the final speed would be?
The problem I have is that the acceleration is not time but space related* going from g=9.81 m/s² at the surface to zero at the core (linearly btw). But if one integrates the acceleration over the way the result would be a squared velocity, i.e. the units be wrong. With a constant accelaration the problem is easy (v=a*t; s=.5*a*t²).
Is it only solvable as coupled differential equations or a single but implicit differential equation? Or am I looking at it from a completely wrong direction?
Or to simplify/generalize the problem: An object is accelerated over a given distance with the acceleration dependent on the position. How fast will it be at the end and how long will it have taken?
*for a rocket the accelaration also changes but over time, so the integration is also done over time and therefore easy.
My physics of gravity never reached that point. My first guess is that the slope of the gravitational curvature would gradually increase to the maximum possible for that mass but I wouldn't be sure of the progression/graph for a given point. If you have the formula to calculate gravity at any given depth an integral should do the trick.
You'll have to ask a professor of physics for a more detailed solution though.
As I said, the gravitational pull at each point is clear (linearly falling from g to zero) but how to I correlate time t and location x?
a=f(x) but to get to v one has to integrate over t not x or the result is not m/s but m²/s².
So I have to somehow replace x with t but for that I'd have to know x(t) which is the thing I want to calculate in the first place.
Interestingly it is easy to calculate the energy needed to move the object in the gravitational field because that is not time-dependent.
For the velocity you could cheat and say that all the gravitational potential energy must have been converted to kinetic energy at the centre and set 0.5mv^2 to it :).
Otherwise, if G is Gravitational constant, M mass of earth, R radius of Earth, r distance of object of object mass m from centre of Earth, at time t you get
md2r/dt2= -(GMmr)/R^3 (from Newton)
Which is of form
d2r/dt2+kr=0
Where k is a constant. Either by recognising it as the equation of a sinusoid from pendula/Hooke etc, or mathematically realising that for a second derivative to be able to cancel itself sin or cos is a good bet we can choose a test solution to be either cos(wt) or sin(wt).
We know at time zero that r is R, so choose the cos form and assume solution is of form
r=Rcos(wt)
For boundary conditions we know at time 0 from Newton above with r at R
d2r/dt2=-GM/R^2
or by differentiation
-Rw^2=-GM/R^2
So w=1.24e-3
So from wT=2pi we get period as: 5062 seconds.
Now we've got r=Rcos(wt) as the equation of motion we can work out the rest.
At 1/4 the way through the period (90 degrees phase) differentiation gives the velocity will be
-Rwsin(1265.5w)
Where the sin value is at the pi/2 maximum and gives a velocity of 7898m/s.
(apologies for not working in g – Physicists don't like parochial units ;) ).
If it works, say Hi to DaveL and Bluenose for me.
edit:
Change "speed" to "velocity". Get kicked out the Physicists union for putting a minus sign on a "speed".
I also thought about the kinetic energy solution but was unsure whether that would work.
I think it will take some time to digest your solution.
But what about the more general problem with the acceleration an optional function of x with object accelerated along x?
I hated differential equations in math at school and at the university and have forgotten most about them apart from the most simple problems.
Quote from: Swatopluk on November 29, 2009, 09:39:09 AM
I also thought about the kinetic energy solution but was unsure whether that would work.
I think it has to. There's nowhere else for the energy to go and it complies with Physics' inviolate First Lancashire Law "You don't get owt for nowt".
If P is density of Earth, and remembering volume of sphere is 4*pi*r^3/3
If you start with your particle at the centre and push it up a bit the work done is Force * Distance
dw=(G*m*4*pi*P*r^3)/(3*r^2)*dr
integrate
(G*m*4*pi*P*r^2)/6
and evaluate at bounds 0 and R
(G*m*4*pi*P*R^2)/6
But by definition P is mass/volume so substitute P =M/((4*pi*R^3)/3) gives
(G*m*4*pi*R^2*M*3)/(R^3*^*6*4*pi)
or
(G*m*M)/(2*R)
By Conservation of energy this equals 0.5*m*v^2
so
v=sqrt((GM/R))
which comes out to the same value as before, 'kin fast as it's known in Physics circles.
Quote
I think it will take some time to digest your solution.
Feel free to ask about any bits.
I suppose getting from
d2r/dt2+kr=0
to r=Rcos(wt)
is where I omitted steps. We know that to match the equation our r expression in t must have the property that its second derivative can cancel the value of its zeroth. We know that both sin and cos have the property that if you differentiate them twice you get a constant times the original value back, but with the sign negated. Therefore we can propose our r expression is a linear superposition of one or more sin or cos terms, maybe with a constant term.
r=A*cos(wt)+B*sin(wt)+C
But we know at time zero r=R, and dr/dt=0 so there's no reason to keep B and C, as we have no boundary conditions requiring them.
d2r/dt2=-GM/R^2
gives
-w^2*A*cos(wt)=-(G*M*r)/R^3
which at time zero gives
w^2*A=(G*M)/R^2
A is clearly R giving the value of w as SQRT((G*M)/R^3)) as before.
We could equally well express r in terms of sin but would need a phase shift to get the correct boundary value compliance at time 0.
r=Rsin(wt+(pi/2))
Quote
But what about the more general problem with the acceleration an optional function of x with object accelerated along x?
I think it's always going to boil down to spotting appropriate solutions to the differential equations and matching boundary conditions. For particular situations I suppose choosing Hamiltonian or Lagrangian approaches might give a shortcut, like the energy conservation one.
Quote
I hated differential equations in math at school and at the university and have forgotten most about them apart from the most simple problems.
Don't worry. You still remember far more Physics than I do Chemistry (despite Chemistry being a minor sub-category of Physics ;) )
edit:
Add dr/dt boundary condition value and fix missing density from integrand.
Now I begin to remember the stuff about the angular functions. I hope those memories don't last ;)
But there was something worse than 'simple' differential equations: Fourier (+Lagrange) transformation and analysis.
I think when our Prof did Lagrange was one of the few occasions where I suffered what we in Germany call a Filmriß.
Although I was technically awake since I made the checklist how often he used his standard phrases/speech mannerisms (his most favorite popped up up to twice a minute), when I left the room afterward I was unable to recall anything he had said (including the very topic!). Must have been similar to hypnosis I presume. No, there were no embarassing photos of naked dancing :mrgreen:
That was my Linear Algebra teacher!
Quote from: Swatopluk on November 30, 2009, 09:17:45 AM
Now I begin to remember the stuff about the angular functions. I hope those memories don't last ;)
Bonus easy question. How have I cheated with N3 in the energy calculation, and does it matter much?
Quote from: Swatopluk on November 30, 2009, 09:17:45 AM
But there was something worse than 'simple' differential equations: Fourier (+Lagrange) transformation and analysis.
My favourite. ;D
Quote from: Griffin NoName on November 30, 2009, 11:45:32 PM
Quote from: Swatopluk on November 30, 2009, 09:17:45 AM
But there was something worse than 'simple' differential equations: Fourier (+Lagrange) transformation and analysis.
My favourite. ;D
What do you expect with stuff designed by two Frenchies? Probably the same people who designed the controls on those old Citroens.
Stick with Newton (known as "Da Man" in Physics circles) or Hamiltonian techniques (so much fun they're named after Nelson's mistress, Lady Hamilton).
Be silent about Hamilton!
Every lesson in quantum mechanics began with the professor writing HΨ=EΨ on the blackboard.
That equation looks so harmless and yet turns out to inevitably lead to pages and pages of cryptic symbols that one has to pretend to comprehend. Even Einstein hated it! (and still got his Nobel for work that now is considered to be part of it*)
Math is not a totally closed book to me but there are limits. Occasionally I manage to get some tricky stuff done (for entertainment usually), at other times I am defeated by elementary stuff. For example I have totally forgotten how I solved the problem to adapt the barometric equation for non-constant g. I did that because I wanted to know what air pressure one could expect at the core of the Earth. On problem I occasionally try to solve is how to hit a ballistic object with another** dependent on limited data. The solution would have to yield values for horizontal and vertical angle, initial velocity and time. I originally wanted to use that for a game.
*still known to remarkably few. It's a notorious killer in quizzes.
**i.e. hitting an incoming shell with one of your own before it comes down on your base.
Quote from: beagle on December 01, 2009, 07:10:24 AM
What do you expect with stuff designed by two Frenchies? Probably the same people who designed the controls on those old Citroens.
You should know that without Fourier & Lagrange we would be still sending messages with pigeons, right?
And the old Citroëns are awesome, active suspensions before everybody else.
:P :P :P
Quote from: Sibling Zono (anon1mat0) on December 01, 2009, 03:53:06 PM
You should know that without Fourier & Lagrange we would be still sending messages with pigeons, right?
They still did that during the World Wars
Hmmm. Maybe. It's just nobody since has thought it was a good idea to stick all a car's controls on something obviously inspired by a wine bottle. Although the Swedes are pretty good at hiding the sidelight switch, it has to be said.
http://www.citroenet.org.uk/miscellaneous/prn/satellites.html (http://www.citroenet.org.uk/miscellaneous/prn/satellites.html)
Don't let your francophobia take over, those consoles are very cool.
:mrgreen: :mrgreen: :mrgreen:
Seriously, I find them cool, although you might like something like this better:
(http://www.rrsilvershadow.com/Best/Camargue%201979%20wit%20dashb3%20bew.jpg)
http://www.rrsilvershadow.com/EDashb/Dashb2.htm
I don't. ;) :P
I always wondered what my car looks like in the front. You'd think Rolls Royce would know which side to put the steering wheel though.
Quote from: beagleBonus easy question. How have I cheated with N3 in the energy calculation, and does it matter much?
...And the answer is.
N3 says that for every action there is an equal and opposite reaction, and as Galileo said (somewhat quietly) "Eppur si muove". The Earth isn't nailed to the sky so it will pick up some velocity in the opposite direction (Conservation of Momentum will say how much).
No it doesn't matter because:
Swato will never get funding for this thing, even from Dubai.
If he tries to build it he'll be busy with tunnelling opportunities for centuries, and the air conditioning bill will bankrupt him.
For anything he can carry the mass will be so small that the energy picked up by the Earth will be something like twenty plus orders of magnitude smaller than that picked up by the object.
The velocity will be in the opposite direction to the particle so the effect on the relative velocity will be reduced still further (and that's what's going to count if it hits the sides).
We went to France for our holiday this year. I think the British have gone right off the French because there was hardly a Brit there besides us.
It's back to the Mumbles next year...at least you can get decent Ice Cream there.
Something to do with the Pound to Euro conversion? :o
Non!
Well yes, that did have something to do with it...British MP's expenses claims have put our currency in the toilet.
I can see many uses for Swato's idea. I bet if he put a page up on the internet for donations he would get some !
After the Byzantine paper, I'm sure he would be able to write a very compelling case for donations.
:mrgreen:
Just market it as a bottomless pit in which to throw money. In advertising honesty always carries the element of surprise.
But it wouldn't be bottomless. Someone would have to stand above/below with a bucket?
Lucky them. Catching pound coins at 17,000MPH. I think a plastic bucket might be out of the question...
If you leave it open there is no vacuum and the air's density will raise to very high levels preventing any coin to move faster than it would sink on water. The bucket would have to withstand the pressure, though.
Swato originally said no air, but that was before the financial implications sunk in. Perhaps he'll let us tweak the spec now. Assuming he's not already busy digging.
1) Why was it only mammals that evolved brains that do the sorts of things ours do and which we believe mark us out as the highest beings?
2) If other earth beings have evolved brains that do the sorts of things ours do then what are they and where are they? :o
I think birds have evolved rather convergently with mammals, despite coming from a rather different branch of the base stock, and probably for the same original reason - eating bugs. ;D
Other animal phyla / classes tend to either not overly developed the 'intelligence' bit (i.e. brains that do the sorts of things ours do) or do not typically exhibit the same degree of sociality / gregariousness that makes them people-ish.
I've had a pet beta with enough of a personality to wonder whether we couldn't breed intelligence / peopleness into animals that do not typically show it.
We cannot be sure about some species of dinosaur (although they are now considered to be mammal like reptiles).
Cephalopods show huge potential but they are currently too shortlived (surprisingly the huge calmars seem to have a life span of significantly less than a decade).
One things seems to be clear: brains consume lots of energy, so only creatures with a strong and constant metabolism have a chance. Also only rapacious creatures seem to have the incentive.
To my knowledge dinosaurs = birds.
---
The development of intelligence if definitively convergent and seems to relate to a combination of physical (size & physiology) and environmental factors, under those conditions from cephalopods to birds (corvids and parrots) to mammals (elephants, cetaceans, primates) we see some common themes involving language, gregariousness and abstract reasoning, with that last one apparently more evolved in us.
In our specific case there seems to be a double jump, primates required stereo vision and some level of intelligence to deal with their movement over the branches, great apes due to size have to spend more time on the ground where they are more vulnerable, and apparently we had to deal with a significant change in habitat in Africa from jungle to savanna which left us even more exposed to predators. It is suggested that the pressure selected the smartest individuals making an already intelligent animal smarter.
It is perfectly plausible that if any of the species from the groups named above is forced through an equivalent kind of selection in their environment they will make the second jump to a higher abstract and numeric reasoning.
Still physiology plays a role, cetaceans seem to have a very high intelligence but their physiology prevent them from "building things" which not only is one of our poor ways to measure intelligence, but also creates a pressure on the abstract reasoning side. In the case of cephalopods as Swato pointed out their lifespan is particularly short making difficult a second jump. For elephants is hard to determine if their size is hindrance on the process or not.
My perspective is that depending on changes on the environment the birds in the group and the primates have better chances of making the jump, but it is a complete conjecture on my part. :-\
Hmmm. The Octopus seems to have become a tool user.
[youtube=425,350]1DoWdHOtlrk[/youtube]
If there will ever be human (bodily) exploration beyond the solar system there is a need for effective propulsion systems (i.e. better than chemical rocket drives).
One standard idea is to use particle accelerators. Usually depicted are long linear accelerators for heavy ions. But however long they can be built the actual acceleration time will be short because the particle can only run along once. Current large particle accelerators on Earth are usually circular in order to give the particles extra speed with every cycle. If now such a circular device would be attached to a linear one, would this increase the thrust of the spaceship drive because the particles leave the ship at higher speed (=momentum) or would only the acceleration in the linear part count because the circular part does not add lateral momentum but only angular momentum?
If the circular part does not add momentum by itself in the Newtonian sense, would it have an effect because it 'adds mass' through relativistic effects, i.e. making the particles heavier before the enter they linear accelerator (while on the other hand decreasing the acceleration time because a faster particle would spend less time in the linear part)?
My immediate guess reaction (with some provisos) is that it counts.
I think you would have to have to have two independent contra-rotating cyclotrons with parallel, or at least in the same general direction, exit accelerators to avoid:
1 Creating a giant Catherine wheel.
or
2 Needing to waste fuel in side thrusters to inhibit rotation caused by N3.
Without attempting to do the maths the reason I think it must count is that from a long distance what you see is two beams of high speed particles heading one way, so Conservation of Momentum says that (whatever the internal detail of the system) something with equal momentum must be going the other.
The second proviso is to do with the accelerating fields. Fields also carry energy and momentum, and if you are chucking out charged particles of sufficient bulk to move a space ship then you might not be able to assume the accelerating fields are symmetric, carrying small momentum compared to the particles, and unperturbed by the particles passing.
They might be radiating energy and momentum asymmetrically into space, and it is the combined momentums of particles, field and spaceship that have to add up.
P.S. You also have to lose the other charge pairs of the particles.
I'm assuming you're dumping them over the side at low velocity, or
using the +ves in one cyclotron and the -ves in the other
(might be tricky finding exact same mass charge pairs; Could put
an unbearable strain on the Dilithium crystals).
Sounds like two synchronized particle accelerating 'coils' doing the dirty work. I wonder how light and powerful something like that could be made to make sense as propulsion. Considering the staggering energy requirements of such a drive I wonder if more conventional means (like a water drive) won't be more energy efficient at least. Current ion drives have barely the lift of a piece of paper without relativistic speeds (290.000 m/s on VASIMR (http://en.wikipedia.org/wiki/Variable_specific_impulse_magnetoplasma_rocket)), precisely because the faster you push a particle the increment in energy input follows relativistic equations. I doubt the sweet spot will move towards relativistic speeds any time soon, but I have to admit that the idea is quite interesting.
Plan B (http://en.wikipedia.org/wiki/Sunjammer).
Quote from: beagle on February 05, 2010, 07:16:19 AM
Plan B (http://en.wikipedia.org/wiki/Sunjammer).
Robert L Forward proposed a solar sail with an external propulsion unit: a giant sun-pumped laser gun. Put the laser in close orbit around the sun, say between Mercury and Venus. But, tilt it's orbit such that if the orbit were an 'equator' the North Pole points in the direction you wish to travel. That way, the laser is never in the sun's shadow for your trip. As we all remember, a laser is Light Amplification by Stimulated Emission of Radiation-- that is, you "pump" light-energy into the device-- why not use direct solar energy to power it?
As an added benefit, you can use the engine for communications as well as thrust: modulate the beam in some fashion-- say switching it on/off, or if you're able, fluctuating it's frequency between two or more modules-- the more different frequencies, the more 'bits' you have in your communication beam.
How to use it for return communication? That's just as easy: the solar sail, to work,
has to be reflective of the frequency(ies) of your laser beam. For efficiency, your sail material has to be almost nebulous-- some form of molecular film or near-film, say 10 km in diameter. Such a film cannot have massive cables, thus you'd have thousands, if not millions of think strands attaching the sail to the ship. You place molecular actuators at the end of each strand, and make individual strands conductive--- adjoining strands complete the circuit, while maintaining tremendous redundancy-- a must, as the sail
will get punctures along the way. Anyway, these actuators will flex the sail a bit, changing it's "aiming" point slightly.
At as little as a few light-hours, this sail flexing will swing the return-bounce from the beam well off the receiver mounted at the laser-engine. This swinging of the beam away-and-back represents one. A steady beam over a given clock-cycle represents a zero. The clock-cycle is determined by the beam itself: as it switches on/off, or the frequency is modulated.
Thus, you have your return communication cycle, embedded within the data on the outgoing beam. Naturally, the return signal takes twice as long as the outgoing message.
And yes...... I've given this much thought in the past.
:D
Edit: Now, some are going to point out a potential problem: the laser is continually moving with respect to the line-of-travel-- minute adjustments of the beam's tilt can easily compensate for that, keeping the ship on track. But, you'll say-- what of the return beam?
By the time direct ship-to-earth beams become too weak to be useful, say about a year out-- the return beam will be spread out enough, that it's diameter would easily be larger than the platform's solar orbit-- such that it won't matter where the platform is in it's orbit. And the deflection would make the return beam miss the orbit of Pluto or more-- such are the magnifying effects of such very long distances-- a few fractions of degree off-target, and at a light year, your beam goes wide by the time it gets back to earth's neighborhood. If the beam is that wide, why not put the receiver on Earth? You could-- but, once in a great while, the Earth would be in the sun's shadow, unless your journey were directly "north" or "south" with respect to the earth's solar orbit (equator). A platform in orbit around the sun, but 60 degrees 'ahead' or 'aft' of the earth would solve that-- but why not put the receiver on the platform, which was deliberately put in an orbit such that the sun could not cast a shadow.
Careful, belt-and-suspenders people will suggest to place two (or more) receivers in various locations within the solar system, as a redundancy. An excellent suggestion. :)
Stanislaw Lem had similar ideas. In Fiasko the initial thrust is provided by a huge battery of lasers on a moon of Jupiter that is aimed at a reflective plate at the bottom of the interstellar space ship. Once the ship is fast enough it collects interstellar hydrogen and 'burns' it in the ship's own drive (whether this is technically feasible is debated among scholars).
Btw, Lem estimated that a spaceship could reach the Andromeda galaxy within the lifetime of the crew if the whole Earth moon could be used as fuel
---
I too had the idea of contra-rotating twin accelerators to compensate for angular momentum. My design would use several of those pairs forming a torus with fusion power plants forming a ring inside. The linear accelerators would run through the center.
If heavy ions made from neutral particles (e.g. from noble gases) are used the charge pair would be electrons that could be disposed of easily.
The whole point of using large (and heavy) accelerators is to make use of relativistic effects in order to overcome the efficiency problems of ion drives.
All interstellar drives under serious discussion I know of are of the type 'low acceleration over very long times'. If the crew needs gravity, it will have to use the centrifuge effect.
Travels directly 'north' or 'south' have the advantage of always having contact with all places in the solar system but the disadvantage that the initial orbital velocity cannot be used. That's also the reason why everyone tries to get the launching pads as near to the equator as possible. The Russians have to put more fuel into their rockets because the 'push' of the rotating Earth is weaker at their latitudes than in Florida or French Guayana.
Speaking of Light Sails and lasers, has anyone read The Mote in God's Eye, by Larry Niven and Jerry Pournelle? A good story, and it goes into this question in some detail.
Quote from: DavidH on February 05, 2010, 11:44:01 AM
Speaking of Light Sails and lasers, has anyone read The Mote in God's Eye, by Larry Niven and Jerry Pournelle? A good story, and it goes into this question in some detail.
I had forgotten that aspect of the story-- perhaps it's time for a re-read. :D
Have you read the follow-on stories? Forgive me, but I cannot recall the exact titles, unfortunately. 'The Gripping Hand' was one, I think.
Quote from: Bob in a quantum-state-of-faith
Have you read the follow-on stories?
No, I haven't seen them. I rarely buy SF new, so I just have to keep my eyes open in the second-hand places. Pournelle & Niven are high on my permanent look-out list. Thanks for the tip! ;D
Quote from: Swatopluk on February 05, 2010, 11:17:14 AM
The whole point of using large (and heavy) accelerators is to make use of relativistic effects in order to overcome the efficiency problems of ion drives.
I think the problem is that to increase the mass of the expelled ions by just one Kg each second would take of the order of 10^17 Joules/S, i.e. the approximate energy output of 20 Million PWRs.
Yeah, but if each ion weighs a kg, then the change in momentum would be enormous.
Actually, I do not believe that homo sapiens will ever travel to the stars bodily. Too many chances for species suicide or at least going back to an essentially pre-industrial age.
Not so easy question: why is krill and zooplankton attracted to cold waters more than warm waters (specially in the Pacific ocean)?
Warm waters are usually poor both in oxygen and nutrients.
E.g. the seas around Galapagos are normally icy cold but teem with life. When El Nino hits, the seas warm up and marine iguanas and sealions starve in large numbers because there are neither fish nor algae left to feed on.
Ayuh, gases dissolve better in cold water than warm - easily observed by opening a warm beer at the same time as a cold one.
I suppose this might hold for phytoplankton as well - less CO2 in the water might make conditions less favourable, but that's pure speculation.
Fair enough, here's another question:
There's a current television ad which describes wind energy as being "renewable". Is this technically correct?
Interesting question - technically it's solar energy and the sun isn't actually renewable. ;)
From the way I understand it, taking wind energy out of the atmosphere should reduce the total kinetic energy of the atmosphere (side question: could enough turbines theoretically reduce the occurrence of hurricanes?), but the energy originates primarily in the sun, AFAIK, and for our purposes is renewable.
Right now, wind turbines are manufactured, transported and constructed using primarily fossil fuels - until the cradle-to-grave mining and processing of raw materials, manufacturing of all related parts, transportation, construction, maintenance, disassembly and disposal / recycling of a renewable energy capture system is achieved using the energy produced by that system, it's not IMHO truly renewable energy production. However, we aren't likely to achieve an electrically-based industrial sector until electricity becomes much cheaper than burning fossil fuels, which will depend on cheap capture of renewable energy. The introduction period of renewable energy generators should be seen as a ramp-up to a renewable energy economy instead of a direct and immediate off-set of fossil fuel use, IMHO.
Renewable possibly in the sense that winds are constantly 'renewed' and will remain in such pattern as long as our primary (the sun) keeps shining. On the same token hydroelectric and solar depend on the sun and will be around for a long time. Geothermal depends on whatever makes the center of our planet hot (quite likely a natural fission reactor) and will remain until said reactions stop in a long while. In both cases we are talking millions or billions of years.
That is in contrast to fossil fuels of which there is a finite amount stored on the planet and which are likely to last for the next 100-300 years at the current rate of consumption. In a completely technical term fossil fuels can potentially renew themselves only that the process of renewal is extremely slow taking millions of years.
In general and simplified terms wind/hydro/solar/geothermal are practically unlimited, fossil fuels are not.
Quote from: Sibling Zono (anon1mat0) on February 25, 2010, 06:34:13 PM
That is in contrast to fossil fuels of which there is a finite amount stored on the planet and which are likely to last for the next 100-300 years at the current rate of consumption. In a completely technical term fossil fuels can potentially renew themselves only that the process of renewal is extremely slow taking millions of years.
A quick proof of this is that CO2 levels in the atmosphere have increased since fossil fuel use became widespread. If nature could renew fossil fuels at the rate we consume them, there'd be little-to-no issue with CO2 increases. There are some fringe mutterings about biogenic hydrocarbons (directly formed by bacteria, instead of from sedimentation of dead organic matter), but while this may be technically possible I personally think that any suggestion of widespread biogenic HC production is mostly justification for treating fossil fuels as a renewable resource.
It would be interesting to calculate an estimate of natural petroleum formation rates, and see whether this amount would be renewable enough to supply the petrochemical industry in theory. In reality, extraction is the issue and nobody has the time to sit around and wait for new oilfields to form, but we should be able to squeak by on residual reserves if we quit using hydrocarbons for fuel. It's not technically necessary, but in many cases it's likely much more energy efficient to build on petroleum derived carbon skeletons than to build molecules from the ground up or extract the precursors from biological sources.
There are experts that say We will be the new oilfields in the distant future since we are on the path of (re)creating the conditions that led to the formation of those we currently exploit.
So the question should be: are we renewable?
Renewable, yes, sustainable, that is a completely different matter.
I think we are like batteries. Can be recharged a number of times but eventually won't hold a charge any longer. I think I must have come from a faulty batch,
Quote from: GriffinI think we are like batteries. Can be recharged a number of times but eventually won't hold a charge any longer. I think I must have come from a faulty batch,
Same here, Griffin. After a moderately active week I'm exhausted and aching all over. :'(
Can something be defined not inappropriate without being appropriate?
eg.
It is not inappropriate to hand someone an umbrella when it is raining ~true
Whether it is appropriate to hand someone an umbrella when it is raining is irrelevant ~true
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Wait, are you suggesting that it isn't appropriate to hand an umbrella when it's raining? I fail to see the gray area.
I think "not inappropriate" is usually not used in Boolean logic, but in tri or multi-state human value judgements. e.g. "Some people feel it would be not inappropriate for Ant and Dec to be bludgeoned to death with a cricket bat". By encompassing the middle-ground as well as the appropriate it evades the element of incitement.
Quote from: beagle on April 05, 2010, 05:28:45 PM
I think "not inappropriate" is usually not used in Boolean logic, but in tri or multi-state human value judgements. e.g. "Some people feel it would be not inappropriate for Ant and Dec to be bludgeoned to death with a cricket bat". By encompassing the middle-ground as well as the appropriate it evades the element of incitement.
:ROFL:
Zono, I think I am asking whether "X is appropriate" is exactly the same as "X is not inappropriate".
An analogy:
Sound. An MP who hasn't fiddled the expenses yet.
Not unsound. Nothing was proved.
Erm, I think I get it although I still don't get the umbrella example, is there any social cue I'm missing about a person getting wet under the rain preferring the sky than an umbrella? Is giving umbrellas a faux pas in the UK?
The umbrella was a red herring.
I think it would not be appropriate to give commie fish to people during rain.
It wouldn't be appropriate to give an umbrella to a motorcyclist in the rain... :P
It would not be inappropriate to give the finger to tea partiers -- oops! -- wrong thread...
All this has been very interesting but I still can't write my essay ;)
It's appropriate to give candy to well behaved children.
It's inappropriate to make a habit of it?
No Zono, that construction is opaque and contains no double negative :mrgreen:
How about, is it not inappropriate to take candy from a baby?
Babies should not eat candy! :mrgreen:
Quote from: Griffin NoName on April 06, 2010, 02:32:21 PM
No Zono, that construction is opaque and contains no double negative :mrgreen:
So, it's not inappropriate to give candy to well behaved children (as it is inappropriate to give candy to children). :P
EEEEEEeeeeeek! I am more muddled than when I asked the question. It is inappropriate to muddle someone trying to write an essay !
Quote from: Griffin NoName on April 07, 2010, 05:43:27 PM
EEEEEEeeeeeek! I am more muddled than when I asked the question. It is inappropriate to muddle someone trying to write an essay !
To be honest, if you're having this great dilemma over just the one word then the outlook for completing a whole essay is not great. Had you considered a haiku as a possibility instead?
A haiku of 3,000 words ?
I am having extreme trouble writing the essay (I hate the topic) - I wrote one essay with no trouble at all (I liked the topic) but this one ugh.
They say that their essay titles always have more than one meaning and I have latched onto the word "appropriate" in the title as being the alternative meaning signifier, the other words being too straightforward.
I am most likely anticipating them being more clever than they are and over-complicating things.
Any suggestions other than a haiku welcome ;D
Inappropriate?
Or it is appropriate?
Meh. Here's a haiku.
What about Stabreim?
Fornyrðislag for the basic text
and Dróttkvætt for the conclusion :mrgreen:
Thanks for really useful haikus :mrgreen:
Another question. This has nothing to do with my essay.
Why don't wild animals get ill from drinking contaminated untreated water?
They have a stronger immune system bexause those with a weak one die young or are mendeled out otherwise.
Predators and scavengers are extra strong there because they have to survive on meat of sick animals or rotten emat resp.
There also usually is an adaption to local diseases. That's even true for humans. Natives often have little problems while foreigners get the shits.
You also have to account for a far lower life expectancy, many of our long term problems happen because we outlived the natural expectation our bodies would have in the wild, IOW having higher concentrations of mercury or other poisons would be deleterious for a longer life but the animal will likely die before a long term contaminant takes its toll.
They do. They also have a whole raft of other problems to deal with, and it's usually one of them that does them in, predation, starvation, getting smacked with a big stick for looking unappealing, that sort of thing. Rats, those most excellent of opportunists, will only nibble a new and unknown foodstuff, then, if there are no unfortunate side effects, take a bigger bite etc. They do the same with water, just drink a little. then a bit more.
The long-term exposure get 'em too... long-livved beasties bioaccumulate all sorts of nasties and probably get cancer as much as similarly-exposed humans do. Actually, we may be more resistant to certain toxins (benzo(a)pyrene and other PAHs ) due to our long-standing association with fire.
In that sense long term nasties are possibly worse for smart long lived creatures as matriarchs and patriarchs that otherwise would lived long to teach their clan what to and what not to do die earlier than they would have otherwise.
But the great majority of creatures die well before that. An informal way to tell the average in the wild for any species is to take the age at which they can procreate successfully plus the time for the infant to learn how to survive on his/her own; a simpler way is to multiply the age at which they usually reproduce by two. In our case that number is between 22 and 30 which is what our ancestors used to live*. Everything outside are the nice exceptions that confirm the rule.
*or when our warranty expires ;)
Ayuh, the main reason you don't see sick animals in the wild is because they already died. ;) :P
Do wild animals instinctively drink upstream from where the crocodiles shit?
There is no upstream from where the crocodiles shit, unless you are upstream of all crocodiles!
I've heard rumours to the effect that many European cities are required to place their sewage-treatment outfall pipes upstream of their drinking water intake pipes, to ensure that adequate treatment is being conducted (because there is always someone else downstream). Is this true?
Quote from: Aggie on April 08, 2010, 08:18:14 PM
I've heard rumours to the effect that many European cities are required to place their sewage-treatment outfall pipes upstream of their drinking water intake pipes, to ensure that adequate treatment is being conducted (because there is always someone else downstream). Is this true?
You mean they'd rather the citizens died than have their quality assurance suffer?
No, more that they'd rather drink their own sh*t than their upstream neighbours (assumes everyone on the river follows same policy). Better the dookie you know... ;)
Just watched a documentary on research dealing with issues of cousin marriages in Pakistani communities - health related - high risk of children with (quite dreadful) disabilities/diseases.
Then watched a program on Gorillas in the wild.
Made me wonder if animals know not to mate with their cousins? Or are there huge numbers of offspring that die from genetic malfunctions? Is there a difference in way congenital disease is passed on for humans and animals? If not, which one would assume, then how do endangered species ever produce healthy offspring? It's all very puzzling.
will this worry keep me awake tonight? Should not watch TV at bedtimes
I imagine there is a link between a higher mortality rate and a smaller genetic pool, although what makes our 'experiment' different from other animals is that we allow children with defects to survive and in many cases to procreate, plus the fact that we outlive our expiration date and keep procreating after that (as a rule of thumb humans rarely lived beyond 30 as hunters-gatherers). If the genetic disorder manifest itself after that age it doesn't preclude procreation.
Also is worth considering that genetic disorders usually show up in small portions of the population (significantly smaller than 1%) and that our large numbers (plus the media) amplify that signal. In wild species the only thing that matters is that procreation is capable of replacing the current population and frequently many young compensate for those who will die in the process before they're able to procreate.
I've been taught of studies (in Japanese quail, IIRC) that indicate animals tend to find their cousins most attractive as mates, since they are not as genetically similar as siblings, but do tend to be adapted to the local environment. Mating too far outside your genetic heritage leads to maladaption, for animals. The risk of genetic disorders might be worth the adaptive advantage, and populations with too many genes for said disorders might quietly weed themselves off over time. Some disorders are also potentially adaptive, if one gets only one copy of a recessive gene, such as sickle-cell anaemia.
Humans have escaped the need to be perfectly camouflaged/temperature-adapted/right-beak-for-food-type and the rest of the smallish details that can be critical to animal competitiveness, so it's probably less of a concern, and therefore taboos against marrying cousins are far from universal (legal in Canada, iirc).
I think Zono's on to something as well - recessive genetic disorders (the types that show up in inbred populations) only manifest in a small portion of the population, and while lack of genetic diversity leads to lots of carriers of a single recessive gene for these disorders, in the past (i.e. before modern medicine) child mortality from genetic disorders was probably a small thing beside child mortality from pathogen-based disease, and therefore not a strong enough factor to bring about widespread taboos.
Many species have systems in place that encouruage out-breeding, e.g. young males are driven from the group by the older, dominant ones and have to find a mate outside the group.
It also partially depnds on the healthiness of the original pool. A historical example would be Jews in Central Europe. During the ghetto period there was inevitably a lot of inbreeding but since the 'stock' was good to start with, the negative effects were comparatively low. In a way inbreeding can keep out defects that are not part of the original pool. The Romans in classical time had a highly organized but simple system that prevented too much inbreeding. the ruling families/clans formed a cycle. Males of one family married females of the family next in line. For the females the direction was the other way around.
Quote from: Swatopluk on August 25, 2010, 08:18:14 AM
A historical example would be Jews in Central Europe. During the ghetto period there was inevitably a lot of inbreeding but since the 'stock' was good to start with, the negative effects were comparatively low. In a way inbreeding can keep out defects that are not part of the original pool.
Actually Jews do marry cousins quite a lot, not just in restricted gettos. There's quite a few cases in my ancestors.
(one of my mother's distant cousins was married to a distant cousin of my father, so I am related to myself by marriage, but I think that doesn't count ;) )
I guess this was just upkeeping of tradition. In the 19th century it was also heavily discouraged from both sides for Jews to marry outside the 'race'. The non-Jews feared the pollution of their precious bodily fluids and the Jews the slow loss of identity. In Israel today the racism seems to be more on the Jewish side. Some right wing organisations have been founded with the main purpose to destroy relationships between Jews (esp. females) and non-Jews (esp. Palestinian males, religion secondary).
Here is a math question that defeats me.
The random number generator available in your standard programming language software produces a uniform distribution (usually in [0;1]).
I need a formula how to turn this distribution into a normal distribution with a preset standard deviation.
Or better a normal distribution that contains as it main variable the probability of an event to fall within a given distance from the center.
E.g. p = 10% d = 5 m => formula with a random input [0;1] yields a distribution where 10% of hits fall within 5 m of the target and the rest fall according to the bell curve.
If I'm understanding your question correctly, what you do is multiply your randomly generated number (0 < n <1) by the scope of your distribution (ie: if your distribution goes from ~0 for a value -5 and ~0 for a value 5 your scope is 10), center it for your distribution and apply the value of n to your normal equation:
x = (n*10)-5
f(x) = (http://upload.wikimedia.org/math/f/5/4/f541efff72bb57075bc5c9883e9a3a6c.png)
Or perhaps I'm completely misunderstanding the question? ???
Not fully but I found an approximation (the Box-Muller transform) after a wiki odyssey.
normal => uniform is easy, the other way around has no analytical solution, so it is no surprise that I did not find one.
Quote from: Swatopluk on November 05, 2010, 07:56:00 AM
.....the other way around has no analytical solution, so it is no surprise that I did not find one.
This could form your life's work :o
Why is it easier to swallow pills with cold than with hot liquids?
I have great difficulties to get any pill down when the liquid I try to do it with is significantly above room temperature.
1. Possibly child-hood conditioning?
2. More likely, the effect cold/hot has on the back of the throat, contracting/opening, or the epiglotis swells up when hot.
3. The drug companies have a secret agreement to add inaudible messages into their tablets which subliminally order one to get a cold drink.
Gelatin coatings on capsules get sticky, as do some other coatings on tablets. They dissolve better in hot water, so it happens more quickly.
The sticky part is one thing that also occurs occasionally. But I think Griffin's #2 is closer to the truth.
I have to say Griffin's #3 is quite likely. ;D Now, on a similar note:
Why do my insulin injections hurt significantly more when I've had a few glasses of rum? :wine:
I thought alcohol was supposed to act as an anaesthetic. :dontknow:
I think that will depend on the number (and size) of glasses. Maybe you do not drink enough for the dulling effect to set in.
Quote from: Sibling DavidH on December 16, 2010, 08:51:28 AM
Why do my insulin injections hurt significantly more when I've had a few glasses of rum? :wine:
I use insulin needles to inject B12. Sometimes it hurts, sometimes it doesn't. My conclusion has always been that it depends on what the needle encounters - nerves, muscle, veins, etc. Also the actual piercing of the skin itself is sometimes felt and at other times not felt at all. But presume that's to do with other factors like the exact angle it goes in, speed, some needles being sharper than others, etc.
I think that's right, Griffin - it sometimes hurts, often not, and that probably depends on what you hit. Still, when it does hurt, the degree of ouch is very variable. It really seems to me that when I've had a glass or two, it hurts more.
So Swato, your theory is no doubt correct in that if I got totally bladdered and Mrs H injected me (never happened yet), I wouldn't feel it. But it usually hurts less when I've had none at all. Sod's law.
Perhaps a trial to test out the pain threshold/no pain effect of different types of alcohol is called for? :mrgreen:
:ROFL: Brilliant suggestion! Now's the time for such a trial. ;D
I am right handed. If I put a pill in my mouth and lift my mug of coffee with my right hand, I can swallow the pill easily. But if I lift the mug with my left hand then I cannot swallow the pill. Why not?
Hmmm.... Is it a bit like that rubbing your tummy while patting your head thing? ???
Perhaps your right hemisphere isn't convinced/thrilled to take the pill?
Or maybe when you try to drink left-handed, the coffee spills down your dress? ;D
If I had a dress on :o
What are the collection nouns, respectively, for roads, streets, lanes, motorways ? Bonus question :: what is the collective noun for all of them?
I'd say 'ways' or 'man-made ways'
----
Maybe a question For Lindorm
What function do these 'fingers' on both sides of the isolator serve? I have seen the same with 'fingers' only on one side.
(http://static-p4.fotolia.com/jpg/00/11/62/19/400_F_11621902_HF8eAHAonnsUY1dHsIaDZQOrZbBaaWZh.jpg)
http://static-p4.fotolia.com/jpg/00/11/62/19/400_F_11621902_HF8eAHAonnsUY1dHsIaDZQOrZbBaaWZh.jpg
And there is another (seemingly new) type. I did not find a picture, so I changed one of a normal isolator to show what I mean.
What function do these 'bristles have? The are all attached in a circle round the center and seem to be metal.
(http://toadfishmonastery.com/forum/index.php?action=dlattach;topic=293.0;attach=1311)
http://toadfishmonastery.com/forum/index.php?action=dlattach;topic=293.0;attach=1311
Sorry, Swato, I have no idea. I have never seen anything like that on catenary isolators here in Sweden.
A few possibilities:
- Some equipment used close to high-tension wires etc is deliberately "user-unfriendly" as a means of increasing awareness and preventing people from doing a possibly dangerous handling error out of habit or by mistake. For example, the gripping device used when changing high-tension fuses on board a locomotive deliberately has some very sharp teeth along it's length, to prevent you from holding it anywhere but in the insulated handgrips. Perhaps this is some sort of analogue, especially the things depicted on the upper picture?
- Birds are normally not a threat to the catenary, since they are not grounded when they sit on the electrified wires. However, they can under some circumstances (i e when spreading their wings) come dangerously close to othe rparts of the catenary system, and then provide a path for the current. This usually results in a loud bang, a puff of smoke, some feathers and a terrible smell, but nothing more. But sometimes the avian vapourization is accompanied by a major flashover, that can crack isolators or burn off the catenary wires. So, perhaps those spiky things are something to keep birds away?
The fried bird has more than once been the reason for interruption of train service around here.
The extra elements seem to be installed mostly near stations, not on the stretches in-between. But it's in no way universal.
May be a dumb/useless attempt to avoid birds? It wouldn't be the first time.
But will it work for dinasaurs too?
Birds are dinosaurs.
Take a look at this oviraptor:
(http://3.bp.blogspot.com/_LOpbWIPseDg/S65cEHmqvGI/AAAAAAAAAXI/VonGw2mhvW8/s400/oviraptor.jpg)
http://3.bp.blogspot.com/_LOpbWIPseDg/S65cEHmqvGI/AAAAAAAAAXI/VonGw2mhvW8/s400/oviraptor.jpg
Oops sorry, I omitted :irony:
Totally unrelated: Where does the phrase 'don't try this at home' come from originally?
I am guessing it started in the United States as a disclaimer on a daredevil stunt.
Why are some beaches made of sand and some of pebbles?
I think that is just a matter of time and material (some stuff grinds down faster). If you wait long enough, the pebbles will turn to sand unless there is a large geological event taking the beach away completely. Some material (like coral) does not go through the pebble phase though.
This is not the answer of an expert in coastology though ;)
Not an expert either but I do know that white sand beaches are the result of a tropical fish that eats coral and expels white sand. Also watching the sand you can tell that a portion of it is made of seashells ground by the waves against the coast. Perhaps you can't have nice beaches without coral reefs.
No corals in the Baltic but there are sandy beaches. A lot of the grinding is probably due to the action of the glaciers during the last ice age.
How do you get brilliant white underwear to stay brilliant white?
I don't mean the deep dark nasty stains, which are a problem in themselves, but the rest of the garment?
And I've never found the soap products, advertised as especially for whites, work. Which is why I ask the question.
Also, plain bleach is not the answer either as the garments I am considering would fall to pieces.
Oh, and obviously these white garments are not mixed in a colour wash, but washed separately.
This problem has puzzled me for years !
The usual trick is to find the right compound among these (http://en.wikipedia.org/wiki/Optical_brightener)
Quote from: Griffin NoName on April 10, 2011, 06:10:44 PM
And I've never found the soap products, advertised as especially for whites, work. Which is why I ask the question.
Quote from: Swatopluk on April 11, 2011, 08:15:10 AM
The usual trick is to find the right compound among these (http://en.wikipedia.org/wiki/Optical_brightener)
Well, of these are added to the products I have tried, they don't work for me. :'(
The only easy trick I know is to not wear them. ;)
Actually, I'm being somewhat serious - keep your 'dress knickers' set aside for the times you might actually care to have a brilliant white pair on, and don't wear them unless required. Use the old, dingy ones for general everyday use. Retire and replace the good ones as needed. Buy non-white undergarments when possible.
AFAIK, this is a common male strategy for most types of clothes, to ensure you've something wearable that does not have holes or grease stains. ;)
Actually it is washing them rather than wearing them that makes them grey. I read in the wiki article Swato linked to that washing them removes the conditioning that makes them white so the additives to the soap are supposed to replace this but as I said in my experience they don't.
My despair is due to having found a garment that fits properly and the general impossibility of this meaning that I do need to wear it as an everyday practice rather than keeping it for special (which has usually been my answer). I also find that keeping any garment for special means it often never gets worn ;)
Griffin, go with the all-black lingerie wardrobe.
So Stylish!! So Sophisticated!! So Slimming!! :D
Of course, you have to go with no-bleach detergents and cold water to prevent fading, but it's well worth it in the long run. Or maybe, go for ba-roque and choose SCARLET!!!
:D
Yes. I normally wear black. A lot of black. None of the stuff I have fades. Though a crop top mixed with sweat leaked black onto an upper lighter colour garment (but I got it out with "Vanish"). My problem is deep and extensive. They dont make colours in the particular garment in my current size. It's a size there is "apparently" no call for it (translate as not enough would sell in that size). Am I one of only 50 people in the world who are that size? It comes in a choice of black or white. I need and have bought both. I am coming to the conclusion to wear but never wash.
I tend to have the same problem with buying jeans. 90% would require sawing off some of my hip and 9.9% are for people that are as wide as high.
Often I have no actual choice because there are just 1 or 2 jeans of my size there at all (if any) and it's take this one or go without a buy.
No troubles with tshirts or underwear (at least as far as size is concerned).
A bit late as always, so I hope the garment in question hasn't fallen apart by now. ;)
Griffin, do you have particularily hard or soft water where you live? Or are there any particles suspended in the water? Water quality can mean a lot, both directly (lime/chalk stains on clothes) and indirectly (alkali ro sour waters making detergents behave in strange ways). An old wive's trick here in Sweden is to add some concentrated vinegar (actually, ättika, acetic acid at about 12% strength) to the final wash and/or rinse to preserve the colours of a garment.
Our summer house is located on a esker, bearing a lot of iron-compound minerals. This means that the water in the lake is brown-ish, due to partly organic matter from the forests surrounding it, but also from the dissolved iron in the water. Back when we didn't have a well, but did our laundry with lake water, keeping bed linen white was something of a headache. We did have some success with vinegar, but also tried bleaching salts and "Vanish" with varying degrees of success. Vansih usually worked for us, though.
Nowadays, we have a deep-drilled well, which simplifies things quite a bit. Still, when we come down to the summer house after winter, a lot of silt has accumulated in the well-pipe, and the first water that comes from the well is deep brown, full of suspended iron oxide particles.
Quote from: Sibling Zono (anon1mat0) on November 14, 2009, 01:04:12 AM
As I walked in airports this past two days I noticed that servicemen/women had a mirror image of the flag on their shoulders, does any one know why?
I finally have an answer for the question! Today I went by a dunkin donuts and there were two service men on a table to whom I approached and asked why. The answer is that "we don't run from the enemy but
towards the enemy" with the implication that while running with a flag, the poll is closer to the stars therefore the body of the flag would move to the back showing the back of the flag (which looks like a mirror image). There is one implication, the mirror image should be on the right shoulder (if the flag were on the left shoulder it should look correctly).
Now I have to verify that they only use it on their right shoulder.
More flag trivia: we sell flag cases (competitor's image below) in a variety of finishes. An Air Force flag folds to fit quite easily, but the slightly heavier weight Army flag requires ... strong encouragement, if you will ... before being so confined enshrined. Yes, there is an airbase adjacent to the city, but corporate headquarters are firmly in Army country, so go figure.
One of my co-workers is an Airforce wife and she is usually tasked with refolding flags in order to get the stars looking at their best (they *never* line up properly in the classic triangular fold!). We don't always tell the client there will be a re-fold, especially if the flag is a memorial for a recently deceased, or if they are all excited about it "being flown at Fallujah".
(http://www.memorials.com/images/products/FlagCaseVeteran.jpg)
[musing mode/on] I wonder how many flags are raised and promptly lowered to make room for the next on the stack to be briefly raised each and every day at newsworthy locations in order to feed the voracious appetite of politicians and patriots [musing mode/off]
Why do tennis players bounce the ball up and down immediately prior to serving? (I find it irritating, as I do the grunting too).
Irritation has been suspected as the motivation behind some grunting. Monica Seles even got sanctioned (in the sense of punished) for it because it was assumed that the main purpose was to unfairly influence her opponent.
What would it be if tennis was like martial arts ;)
Quote from: Griffin NoName on July 02, 2011, 08:07:42 AM
Why do tennis players bounce the ball up and down immediately prior to serving? (I find it irritating, as I do the grunting too).
At the level the pro's play at, a new ball 'goes off' fairly rapidly (after a couple of dozen hits). The 'ball boys' are issued a set of two dozen balls at the start of a match, and they are cycled randomly in use. Some of them naturally get used more than others. The players are testing each ball before they serve to see if it has 'gone off' (It won't bounce as high or as fast). If one is not to their satisfaction they will throw it to, or sometimes at, a 'ball boy' who is supposed to remove it from play. When there are insufficient balls to keep an adequate stock available, the umpire will call for 'new balls please!', and all the balls in play are retired and a full new set issued.
What are the implications of an electromagnetic wave with a wavelength approaching zero and a frequency approaching infinity? Head for the far end of gamma and keep going.... does it change from a wave into something else? ??? Does it become mass?
I'm curious about the other side of the coin (near-infinite wavelengths), but that seems easier to get a handle on as they'd be low energy to the point of non-energy.
I guess it would condense as matter but the wavelength would have to be considerably shorter than even that of hard gamma-rays.
It all of course requires that the amplitude does not go to zero too.
Yes, assume amplitude is kept nonzero and constant.
White dwarf matter shows up in physics text and occasionally comic books. It is famously very dense with about 10 tons per cubic centimetre. It is in a pysical state known as degenerate but not fully collapsed (as in neutron stars).
My question: if a piece of a white dwarf would be removed and brought elsewhere, would it stay in this superdense state or simply revert to normal because the gravity causing the degeneration is absent?
I suspect that to properly answer this definitively not easy question, a deep knowledge of theoretical quantum mechanics and astrophysics is required. The intuitive answer is that it would likely revert to normal matter in a violent fashion, but considering that quantum mechanics are all but intuitive I cannot say that that would be the actual behavior.
I know less about Quantum Physics than most people, but ignorance has never inhibited me from saying my pennyworth: :mrgreen:
Doesn't it depend on the mass and shape of the detached lump? A big enough lump would surely maintain its state, a small one would not hang together.
Do hot beverages have an effective caloric value based on the amount they heat up the body (which displaces the need to burn food for heat)?
Back-of-the-napkin calculation would suggest that assuming an average consumption temperature of 60 C, this would represent about 22.5 kCal/L. Less than having a spoon of sugar in each cup.
Related question, in that case: Do hot beverages actually have the potential to warm you up? I've felt like I was overheating when eating hot soup or drinking hot tea, but since the amount of actual warming that say, 500 g of 60 C water could perform on a 75 kg body is negligible (roughly 0.15 of a degree), the usefulness in warming up a hypothermic person seems pretty limited.
If one is at a normal body temperature and normal room temperature, the production of sweat might a) take calories to effect and b) provide evaporative cooling that requires additional calories of food-energy consumption to compensate for.
I don't propose a significant effect, but overall, does drinking plain hot water represent a gain or loss of calories?
That looks related to the myth of negative calories, like eating frozen food or stuff that uses up more energy in chewing than it yields in calories. One factor notoriously ignored there is that heat exchange takes place not just between the food and the body but also between both and the outer environment.
As for warm liquids for treatment of hypotheremia, I think the main effect is less in the amount of calories transferred but in the speed it takes place. The heat has to be transported where it is needed quickly without the body having to do much muscular activity. The nutritional calories have to be turned by the body into fuel for muscles and the muscles have to turn them into heat. A hot liquid will transfer its heat to the body instantly.
I suspect that external temperature has a good deal to do with it, that is, if you are in a hot weather the extra heat will force your body to burn energy to cool you, while in a cold weather it will reduce the amount of energy you use to keep your temperature. My hypothesis is that while the actual heat of the hot beverage isn't that great while measured in kCal, it is warming directly your internal organs (which are the ones in critical need of heat) and the energy expenditure of the body to heat it in the same proportion is significantly higher due to inefficiencies while converting fat to heat.
But the inefficency is already in there through the calories given as nutritional value not enthalpy of combustion.
I just watched a really bad explanation of bio-synthesis on TV.
Essentially it went like this:
Making Cynthia:
Clive wotsit took a cell, (cell A) extracted it's DNA and put it (the DNA code) into his computer. Then he took another cell (cell B), extracted it's DNA and threw it away. Then he synthesised the DNA code in the computer (cut to picture of a printer printing out the letters of the DNA code - voice over saying just like this) and inserted it into cell B (picture of piece of paper with letters of the DNA code, shown hovering over cell B- so now cell B has cell A's DNA and is therefore a synthetic life form - Cynthia.
What the hell does "Then he synthesised the DNA code in the computer " actually mean? What did the computer DO? What actually came out of the computer? Why is a computer needed at all.?
It didn't help that he used drops of wax to simulate the cells. :(
Quote from: Griffin NoName on January 19, 2012, 08:46:17 PM
I just watched a really bad explanation of bio-synthesis on TV.
Essentially it went like this:
Making Cynthia:
Clive wotsit took a cell, (cell A) extracted it's DNA and put it (the DNA code) into his computer. Then he took another cell (cell B), extracted it's DNA and threw it away. Then he synthesised the DNA code in the computer (cut to picture of a printer printing out the letters of the DNA code - voice over saying just like this) and inserted it into cell B (picture of piece of paper with letters of the DNA code, shown hovering over cell B- so now cell B has cell A's DNA and is therefore a synthetic life form - Cynthia.
What the hell does "Then he synthesised the DNA code in the computer " actually mean? What did the computer DO? What actually came out of the computer? Why is a computer needed at all.?
It didn't help that he used drops of wax to simulate the cells. :(
Actually? The physical DNA that was inserted was made up of it's base components, and not other DNA molecules.
They used the sequenced DNA of cell A as a road-map, but not exclusively-- they added in some other bits as proof-of-concept, chiefly one that makes the new cell glow under certain light.
But essentially, the copied the majority of the DNA's 'alphabet' into a computer, via gene sequencing methods.
And they took the code--after tweaking it as above-- and used that artificial sequence to re-create, out of raw chemicals, the new DNA.
And finally, using viral methods, the re-inserted the artificially-created DNA into the host cell-- one that, without any DNA, was effectively dead-- it could not reproduce, nor could it repair itself, nor could it metabolize nutrients.
Once the artificial DNA was inserted, the cell started to metabolize nutrients, and soon enough, reproduced-- the daughter cells faithfully glowing just as the parent cell did. And so on-- I don't know how many generations they let it go, before killing the whole batch. Quite a few, I'd imagine.
But the whole point, was at one step, the entire DNA only existed as computer code--
-- in a way, kinda-sorta, they "beamed" the DNA from one cell to the other, via computer code.
There really would have been no reason why they couldn't have telephoned that code around the world first-- it had been reduced to digital information-- one's and zero's in a computer's memory banks.
Kinda amazing, really.
Quote from: Griffin NoName
...and inserted it into cell B (picture of piece of paper with letters of the DNA code, shown hovering over cell B...
Wow! That sounds eerily similar to the way the BVM conceived the Baby Jesus, as explained rather early in my religious
indoctrination education, what with an asexual [object] hovering magically above a sexually reproducing [object] without any physical contact, and all...
:devil2:
Quote from: Bob in a quantum-state-of-faith on January 19, 2012, 10:05:52 PM
But the whole point, was at one step, the entire DNA only existed as computer code--
Sorry, but I don't find that amazing at all. I can't see anything all that clever, once computers have been invented, and once DNA can be reduced to a sequence of letters, about the use of a computer to produce an adulterated sequence (ok, it is a bit clever to define the DNA sequence specifically needed to cause glow, and program the computer to combine etc but still, the basics are all there as far as the computer aspect was concerned). For me that was not the whole point. The whole point seems to me the method of re-introducing the newly sequenced code into the cell from which its own DNA has been removed. To demonstrate this by holding up a piece of paper with a load of letters on it, printed out by a computer, explains precisely nothing. The point of the program was to explain it, and it didn't.
Bob said mostly all about it, the only thing to add is that while the DNA is a copy of a working DNA of other cell this means that potentially someone can build the DNA from scratch in a computer and then use a machine to build the actual molecules and insert them into a blank cell, which is a completely and perfectly synthetic life form. It's a tool for genetic engineering and one with potentially enormous implications.
I've heard we are not too too far off from being able to buy at-home wethacking kits. There are already competitions for this sort of thing, I think.
Quote from: Griffin NoName on January 20, 2012, 08:38:26 PM
Quote from: Bob in a quantum-state-of-faith on January 19, 2012, 10:05:52 PM
But the whole point, was at one step, the entire DNA only existed as computer code--
Sorry, but I don't find that amazing at all. I can't see anything all that clever, once computers have been invented, and once DNA can be reduced to a sequence of letters, about the use of a computer to produce an adulterated sequence (ok, it is a bit clever to define the DNA sequence specifically needed to cause glow, and program the computer to combine etc but still, the basics are all there as far as the computer aspect was concerned). For me that was not the whole point. The whole point seems to me the method of re-introducing the newly sequenced code into the cell from which its own DNA has been removed. To demonstrate this by holding up a piece of paper with a load of letters on it, printed out by a computer, explains precisely nothing. The point of the program was to explain it, and it didn't.
The method of destroying the DNA in the host cell is an old one, and uses enzymes if I recall correctly-- they are microscopically injected into the cell using a really small thingy, under a microscope-- I think. It's been a while since I read about that technique.
The insertion sequence is even easier: they use the viral coat mechanism. A virus is basically a strand of RNA that is covered with a protein engine which permits the RNA to be injected into the cell-- usually through normal channels in the cell's wall. The protein coat fools the cell's membrane (or more specifically, it's "gatekeeper proteins") into permitting the virus's coat to attach. If you remove the internal RNA from the original virus (how? I do not know, sorry) and replace it with the artificial DNA, then the protein coat can do it's thing, and inject your artificial DNA instead.
Re-animating the cell.
Quote from: Sibling Zono (anon1mat0) on January 20, 2012, 09:12:16 PM
.........and then use a machine to build the actual molecules and insert them into a blank cell, which is a completely and perfectly synthetic life form.
Yes, this crucial step was the one not explained in the program. At least, it was not explained properly, as they failed to mention "use a machine to build the actual molecules", but just waved the computer printout around. I don't know why it annoyed me so much.
Quote from: Sibling Zono (anon1mat0) on January 20, 2012, 09:12:16 PM
It's a tool for genetic engineering and one with potentially enormous implications.
Yes. We may self-destruct :mrgreen:
Quote from: Bob in a quantum-state-of-faith on January 21, 2012, 04:15:52 PM
If you remove the internal RNA from the original virus (how? I do not know, sorry) and replace it with the artificial DNA, then the protein coat can do it's thing, and inject your artificial DNA instead.
Yes, they omitted to mention anything to do with viruses at all, never mind the fact that they are the delivery.
It's because if they explain it properly the terrorists win. ;)
LoL@Zono
Quote from: Sibling Zono (anon1mat0)
It's because if they explain it properly the terrists win. ;)
FTFY ;)
I have what perhaps isn't such an easy question. First imagine the following scenario, you strap a wind turbine on the roof of a car, as you move the turbine generates electricity, but also generates resistance and per conservation of energy nothing is really gained. Now, what happens if the turbine is within the aerodynamic envelope of the vehicle? For instance, currently most internal combustion vehicles have their radiators at the front and the air comes through the grilles to help cool down the water, the question is, what happens if I strap a small turbine at the very front where the grill is (again within the aerodynamic envelope), will I gain energy by doing so?
If it's causing drag on the vehicle, it's not going to gain you energy. If it's not causing drag, it's not going to make energy.
I see what you're getting at, but presumably any place that a turbine could be placed to capture wind energy is a place that could be redesigned for further aerodynamic efficiency (i.e. you'd get more net energy by reducing drag). I suppose there'd be an argument for putting this type of a device on a vehicle that wasn't very aerodynamic in the first place.
Hypothetically, there may be a way of ducting a set of turbines to reduce drag by modifying airflow over the vehicle, but simple ducts (without the turbine) would probably be a better job. That's way beyond my level of understanding, though.
With the right design and optimum angle towards the wind one can at least save energy. But only if their is real wind. Real wind and 'drag wind' add vectorially, so the wind as seen from inside the moving vehicle shifts forwards with increased speed thus reducing efficiency. The common example are special sailboats than can sail faster than the wind (and only when the wind comes from the front 180° not from behind).
Quote from: Sibling Zono (anon1mat0) on February 22, 2012, 04:16:55 PM
I have what perhaps isn't such an easy question. First imagine the following scenario, you strap a wind turbine on the roof of a car, as you move the turbine generates electricity, but also generates resistance and per conservation of energy nothing is really gained. Now, what happens if the turbine is within the aerodynamic envelope of the vehicle? For instance, currently most internal combustion vehicles have their radiators at the front and the air comes through the grilles to help cool down the water, the question is, what happens if I strap a small turbine at the very front where the grill is (again within the aerodynamic envelope), will I gain energy by doing so?
That is a good question, as it's rarely a simple case of pure wind resistance with a vehicle.
Here's an example where adding more drag (seemingly) actually decreases the total drag: wingtips on the ends of airplane wings. Due to a complex mix of vectors, as the air flows over the wing, it generates little vortexes at either wingtip.
These simply spin off into the air, creating drag, sure --but not for the airplane itself-- the energy is "dumped" into the atmosphere as it were, not unlike throwing water overboard-- the total water is unchanged (boat/sea) but within the boat itself, it's decreased.
So the wingtip sticks out at an angle, and "catches" these little mini-tornadoes, and actually decreases the total drag on the airplane. In a sense, you are recovering energy that would otherwise be wasted.
Okay, back to a car. If there are similar locations on the car, where the atmosphere is being churned or twisted such that energy is being dumped overboard (and into the atmosphere), capturing that energy would keep it "on board" as it were.
I would think that only using a wind tunnel and some really sensitive measuring instruments, would you see any net benefit.
I'd think, a simpler solution would be to effectively decrease overall drag, rather than to add weight with a (at best) 50% efficient turbine.
However, if you're talking about an electric vehicle, wherein there is already an on-board battery pack? Then a turbine might make sense-- only the weight of the turbine would detract from your total figure.
On the Titanic, it was women and children first. What do they do now since women's suffrage?
Quote from: Griffin NoName on April 20, 2012, 11:24:34 PM
On the Titanic, it was women and children first. What do they do now since women's suffrage?
Actually the Titanic catastrophe was seen as the greatest setback for the feminist movement at the time. In essence the male position was: you get the privileges of getting rescued first but under the condition that you stay a 2nd class human being. And right for the 100th anniversary some RW religious nuts try to get us back there with that same argument. They also claim that the disaster disproves Darwin (since it was not survival of the fittest).
Quote from: Swatopluk on April 20, 2012, 11:42:41 PM
They also claim that the disaster disproves Darwin (since it was not survival of the fittest).
:ROFL:
Actually I just found
this (http://www.msnbc.msn.com/id/47043470/ns/technology_and_science-science/t/women-children-first-shipwreck-code-now-myth/).
The Titanic vs. Darwin link can be found under Unlikely Headlines
Titanic vs Darwin? LOL. That one's easy. Nature creates iceberg, man creates ship, iceberg attacks ship, ship proven to be poorly-designed and run. End of. Natural selection wins, therefore Darwin! ;D
EDIT: It should be "children and their parents first", then a randomisation of the other passengers. It's the only way to ensure equality.
Quote from: Roland Deschain on April 22, 2012, 05:40:51 AM
EDIT: It should be "children and their parents first", then a randomisation of the other passengers. It's the only way to ensure equality.
But there wouldn't be time for DNA tests :mrgreen:
How about "everyone for themselves", then? ;)
Quote from: Roland Deschain on April 22, 2012, 06:51:43 AM
How about "everyone for themselves", then? ;)
That was the official practice and command before the incident that led to 'women and children first'.
Quote from: Roland Deschain on April 22, 2012, 05:40:51 AM
............ a randomisation of the other passengers. It's the only way to ensure equality.
Every ship should carry a passenger randomization computer program. On arrival on the ship, every passenger is given their abandon ship priority number. :mrgreen:
Quote from: Griffin NoName on April 22, 2012, 05:16:10 PM
Quote from: Roland Deschain on April 22, 2012, 05:40:51 AM
............ a randomisation of the other passengers. It's the only way to ensure equality.
Every ship should carry a passenger randomization computer program. On arrival on the ship, every passenger is given their abandon ship priority number. :mrgreen:
Wouldn't that have to be either sealed or encoded? Otherwise, some passengers would always seek out those with higher-priority numbers to exchange for ... perhaps some kind of financial incentive ... or perhaps without informed consent?
mmm of course! deffo don't hand them out. :o
Quote from: Roland Deschain on April 22, 2012, 05:40:51 AM
EDIT: It should be "children and their parents first", then a randomisation of the other passengers. It's the only way to ensure equality.
(being a little tongue in cheek here, and taking DNA's perspective)
Why parents? If the children are saved, both parent's genetic legacy has been carried forward (there may be an argument for allowing one parent to accompany a young child, in terms of parental support). To prioritize parents who may be effectively post-reproduction is ridiculous.
Young adults of reproductive age should take quite as much of a priority as children. In the case of multiple siblings on the same vessel, perhaps it should go to lottery or else the youngest female sibling gets priority. Women first is just sensible as there are more and more single mothers these days and it really doesn't take many men to accomplish reproduction. In addition, women carry forward the additional (very distinct) mitochondrial DNA lineage. Men are really a waste of resources in a world where they are not required for child-rearing.
Those past the age of reproductive ability have no direct bearing on the genetic legacy of the human race - sorry. :(
But those oldsters do keep and maintain the cultural referents and the obscure things (culture-wise) that do not normally come up in day-to-day events.
So leaving them behind, you'd "chop off" those cultural memories/teachings/wisdom*, causing a cultural vacuum. Ripe for exploitation by some nefarious power-hungry plot**.
I'm just sayin'-- it ain't all about passing on the DNA here.
:)
______________________
* "wisdom" is used very loosely here
** example: Constantine's power-grab of roughly 300CE.
No, but in the context of a small-scale sea disaster? Why not? Everyone has an emotional connection of some sort, and human value. In terms of wisdom, social significance and 'replace-ability', small children should not take up room in a lifeboat if there's a dearth of space. In most cases, the parents may be young enough to have more. :-\
These days, perhaps it should just be based on who has the most friends on Facebook. :P
-------------------------------
Here's a funky question... why does one of my armpits smell worse than the other?
This is sometimes fresh out of the shower, so the smell isn't old broken down sweat, but eliminated dietary elements (usually garlic and onion, although cumin is quite distinct when I've been eating lots of it). I don't use antiperspirant, and rarely use deodorant unless things are especially funky.
Do we have one particularly eliminatory pit? Am I the only one that notices this?
Could it be a bias in your nose?
In that one side of your nose is less sensitive than the other? Or have you wiped your pits, and checked the moisture's odor directly? (who hasn't done that just before an important date? heh)
Or it could be due to proximity of the length of arteries coming from your liver, to either arm-- the liver is larger on one side of the body than the other, so I would presume an asymmetry in the arteries and/or veins between the liver and either arm, that is the path of the bloodflow (obviously through the heart).
I would assume the moisture comes from liquids in the blood, but it could be from the lymphatic system too-- which is easily as extensive as our blood vessels.
Come to think of it? There is a lymph node under or near each armpit-- these are frequently removed in women experiencing breast removal due to cancer.
Could it be an infection or other inflammation of your lymph node under the more odoriferous arm? I would check out your body near that area for unusual tenderness, or funny growths/lumps and such.
Odd smells are frequently a "tell" of something else going on-- but just as often, the "something else" is really nothing to worry about.
On what side is it? Is it your active side (the right if you are right-handed)? Since that side is developed more strongly, it could be that there are also more sweat glands (I assume you are not a Mongol. They lack those in the armpits). The smell in any case is caused by bacteria decomposing the sweat.
I insist that I smell like food (with no sweat-decay odour) quite often directly after washing the pit repeatedly. This isn't a new thing; I sweat out garlic and strong odours (as do many people). It is indeed my active side.
Quote from: Aggie on April 24, 2012, 10:40:19 PMThose past the age of reproductive ability have no direct bearing on the genetic legacy of the human race - sorry. :(
Don't see why you should apologise. The UK might as well kill off anyone post-reproductive given the way they treat the elderly it would be a lot kinder.
QuoteDon't see why you should apologise. The UK might as well kill off anyone post-reproductive given the way they treat the elderly it would be a lot kinder.
Only the poor ones. The wealthy get excellent treatment.
Quote from: Sibling DavidH on April 25, 2012, 09:09:56 AM
The wealthy get excellent treatment.
Isn't that true in all cases?
Yes, I wasn't referring to the wealthy. I was referring to the majority.
Quote from: Aggie on April 25, 2012, 12:21:11 AM
I insist that I smell like food (with no sweat-decay odour) quite often directly after washing the pit repeatedly. This isn't a new thing; I sweat out garlic and strong odours (as do many people). It is indeed my active side.
I noticed yesterday evening that the newest issue of the chemistry journal I subscribe to has a lenghty article on the topic.
I just have to find the time to read it.
Quote from: Griffin NoName on April 22, 2012, 05:16:10 PM
Every ship should carry a passenger randomization computer program. On arrival on the ship, every passenger is given their abandon ship priority number. :mrgreen:
It would almost be like the Deli counter in Tesco. ;D
I said "children and parents first" (meaning children up to 18, so that also includes young adults), because it would be harder on a child to lose their parent, and unfair to effectively sentence a child to death when they have not even had a chance at life. Maybe giving tickets randomly to groups of people would be better? That way, either a whole family is saved, or a whole family goes down, although I definitely wouldn't want to be related to the family who goes down with the ship. Losing one member is hard enough, but losing several would be devastating. We definitely need instant teleportation rescue facilities.
The sweat thing is interesting. If it's your most active side, then it's probably precisely because of this that you smell of food more there than the other side. It could also lead to some fun games with your partner. :o
Quote from: Roland Deschain on April 26, 2012, 11:36:51 AMWe definitely need instant teleportation rescue facilities.
Or... perhaps sufficient numbers of lifeboats and jackets? ;)
C'mon, be realistic! Who wants to spend money in something as useless as lifeboats or vests? The moment the boat goes down so does the customer because if (s)he survives (s)he won't be going by ship ever again. Worse even, that is a witness both legally and in the public court. Better if (s)he drowns, and cheaper too...
Quote from: http://www.setbb.com/sudoku/viewtopic.php?t=1432&mforum=sudoku user wapati
I have all the "easy stuff" turned on and then these: UR types 1-4,
x-wing, finned-x, skyscraper (covers sashimi-x), xy wing, xyz wing,
swordfish, finned swordfish, sashimi swordfish, jellyfish, finned jelly,
sashimi jelly, ER (empty rectangle, covers regular turbot),
two string kite (the third form of turbot, skyscraper is the second),
BUG+1 and remote pairs.
What on earth? This was on a Soduko forum - all the posts contain similar. Is there a Sudoku language I have failed to learn?
Quote from: Griffin NoName on May 03, 2012, 05:09:25 AM
Quote from: http://www.setbb.com/sudoku/viewtopic.php?t=1432&mforum=sudoku user wapati
I have all the "easy stuff" turned on and then these: UR types 1-4,
x-wing, finned-x, skyscraper (covers sashimi-x), xy wing, xyz wing,
swordfish, finned swordfish, sashimi swordfish, jellyfish, finned jelly,
sashimi jelly, ER (empty rectangle, covers regular turbot),
two string kite (the third form of turbot, skyscraper is the second),
BUG+1 and remote pairs.
What on earth? This was on a Soduko forum - all the posts contain similar. Is there a Sudoku language I have failed to learn?
I think the only answer to that can be:-
(http://sheamacleod.files.wordpress.com/2012/01/im-not-saying-it-was-aliens-but-it-was-aliens.jpg)
Quote from: Griffin NoName on May 03, 2012, 05:09:25 AM
Quote from: http://www.setbb.com/sudoku/viewtopic.php?t=1432&mforum=sudoku user wapati
I have all the "easy stuff" turned on and then these: UR types 1-4,
x-wing, finned-x, skyscraper (covers sashimi-x), xy wing, xyz wing,
swordfish, finned swordfish, sashimi swordfish, jellyfish, finned jelly,
sashimi jelly, ER (empty rectangle, covers regular turbot),
two string kite (the third form of turbot, skyscraper is the second),
BUG+1 and remote pairs.
What on earth? This was on a Soduko forum - all the posts contain similar. Is there a Sudoku language I have failed to learn?
LoL@Roland
Relief - I have found a website which explains things. I now know what an X-wing and swordfish are. However, I fail to understand much of what is written about them.
Question for the chemically inclined, how hard is to convert ammonia NH3 to H2 and N2?
---
I had some devilishly hard question the other day but I forgot...
Easy, a bit of heat and a catalyst (in essence the same that are used for the synthesis, e.g. platinum or the right kind of iron).
Use enough heat and you won't even need the catalyst.
Going a bit further then, would crashing a rock of ammonia ice in the Martian atmosphere would do the trick?
I think atmospheric friction would not be strong enough. Also material on the surface would primarily just evaporate and drift off and thus not get enough heat over time. The crash on the ground would do a bit but for the same reason be incomplete.
I imagine you could calculate what is the correct size for the Martian atmosphere friction to do so, no? That would be a relatively cheap way to raise the Martian atmospheric pressure for terraforming.
I suspect this could be done biologically, as well... the gaseous diatomic products are lower energy than ammonia, I think. There are microbes that use NH3, I think.
The problem is that I doubt there is enough Nitrogen in Mars to raise the atmospheric pressure, so it would have to be brought from somewhere else (comets, Jupiter, Saturn, Titan) where it's likely in it's ammonia form.
Ayuh, but you could use microbes to crack it once it was there. Besides, according to Wikipedia:
QuoteAmmonia was also detected on Mars, but with its relatively short lifetime its not clear what produced it.[113] Ammonia is not stable there and breaks down after a few hours, so one possible source is volcanic activity.
No assistance required.
The chronic issue with Mars isn't the lack of atmosphere - that's only a symptom of the fact that Mars no longer has an internal magnetic field. Without figuring out how to kick-start the planetary dynamo again, any atmosphere that gets artificially re-established will get knocked back into space by the solar wind. :P
True, but it takes millions of years, once there you can add some from time to time to replenish it.
---
It is clear that without geological activity a planet dies in the long term (not only the geomagnetic field but gasses pumped out by volcanic activity).
The absence of a geomagnetic fields is also not good news for any life as we know it. The field shields not just the atmosphere but also the surface from strong particle radiation. Should the Earth undergo another magnetic pole switch in the near future, the effects would be catastrophic. Not just would the cancer rates go through the roof but also our complete net of electricity distribution would become unbtenably unstable.
Life can go underground/shielded habitats during solar storms, the thing is that I suspect that making the core active again is close to unfeasible(un-fissible?) in the short term, even dumping in all nuclear fuel currently in existence.
It would not need solar storms, the basic level is sufficient, if the shields go down.
To my knowledge this is seen as THE main problem with manned missions to Mars. Areonauts* would either need spacesuits that offer much better protection against radiation (also Martian dust storms work like sand blasting) or they would have to stay most of the day in their shielded craft and could go out mainly at night.
It is also believed that any spacecraft currently under serious consideration would not be enough to shield the Areonauts on their way, should they get hit by a solar storm. Pessimists say that any manned mission to Mars would be suicidal, not because we could not get them safely there and back again but because they all would catch so much radiation that they would withoutexception develop cancer of many kinds.
Effective shields would be too heavy at the current state of the art.
*not to be confused with aeronauts
Quote from: Swatopluk on May 17, 2012, 10:35:12 PM. Should the Earth undergo another magnetic pole switch in the near future, the effects would be catastrophic.
How many catastrophic events are we at risk of ? Which is most likely? Why do we not live every day as if it is our last?
I have a geometry question: Can an infinitely large space contain an infinite number of infinitely large spaces?
Quote from: GriffinWhy do we not live every day as if it is our last?
I think it's because everyday experience tells us that these catstrophes don't happen. We're lulled into a false sense of security.
Anyway, if I lived this day as if it were my last there'd be several rapes and murders. :mrgreen:
Quote from: Griffin NoName on May 18, 2012, 02:53:37 AM
Quote from: Swatopluk on May 17, 2012, 10:35:12 PM. Should the Earth undergo another magnetic pole switch in the near future, the effects would be catastrophic.
How many catastrophic events are we at risk of ? Which is most likely? Why do we not live every day as if it is our last?
That such an event will occur is a certainty but a rather unpredictable one.
Why do some coaches have upside down tusks?
(http://lh5.ggpht.com/-4OJx4L4jQys/S1pl2DNezSI/AAAAAAAAAWc/uRBtzSCOy0w/100_0184.jpg)
Those are rearview mirrors that significantly reduce the blind spot compared to the classic side-mounted ones.
Quote from: Griffin NoName on May 28, 2012, 06:37:22 PM
Why do some coaches have upside down tusks?
Quote from: Swatopluk on May 28, 2012, 06:45:31 PM
Those are rearview mirrors that significantly reduce the blind spot compared to the classic side-mounted ones.
Why don't all coaches have upside down tusks ? ::) ::)
To my knowledge they are not mandatory yet (at least not for old ones, newly built ones may differ).
Since they are probably not cheap, companies will not be eager to retrofit.
And I guess drivers have to be careful not to to hit anything with them.
I know some cases where they reach down far enough to hit people's heads even when they are clear of the bus itself.
They look more like insectile-type antenna...
I wonder what Martians would make of them?
Over here they are known as Schlappohr-Spiegel (lop ear mirrors)
Like a floppy bunny ear I suppose. I am sure they are really upside down tusks. Hopefully not made of ivory :o
(http://www.grancanariamitroland.de/wp-content/uploads/2010/09/schlappohr-braun250.jpg)(http://medien.markt.de/bilder/2011/06/10/17/3ec304ca/medium_image/0/zwergwidderkaninchen_schlappohren.jpg)(http://pe2.hmcdn.de/media/2009/10/14/item/75/84/06/71/item_L_75840671_211919171.jpg)
http://www.grancanariamitroland.de/wp-content/uploads/2010/09/schlappohr-braun250.jpg
http://medien.markt.de/bilder/2011/06/10/17/3ec304ca/medium_image/0/zwergwidderkaninchen_schlappohren.jpg
http://pe2.hmcdn.de/media/2009/10/14/item/75/84/06/71/item_L_75840671_211919171.jpg
Do (esp. head) lice need no oxygen to live?
If they do, why is it not the easiest way to get rid of lice by taking an extended bath and wearing an airtight hat?
The eggs are of course a different problem but should only require a repeat of the above procedure.
Not a truly informed answer but I suspect that a) even while submerged tiny bubbles still remain in the hair, b) some insects are known to enter a kind of hibernation state under critical conditions, c) some birds that dive have lice (although less than non diving birds), and d) the eggs might be the key reason:
Quote from: WikipediaMany lice attach their eggs to their host's hair with specialized saliva; the saliva/hair bond is very difficult to sever without specialized products.
But what about the airtight hat (maybe flooded with helium*)?
*very good at driving out heavier gases like oxygen.
An egg takes 8-10 days to hatch, for how long do you plan to put a head in a helium atmosphere? :o
Well, how long does an adult survive? (That's the original question)
Putting the hat on for slightly longer than that should remove the living samples. The interval between different hat sessions must be smaller than the time between hatching and eggdeposition of the hatchling. It should not be necessary to play the game longer than a bit above 1 incubation period.
Much simpler to smack the beggars with a 4lb hammer.
It's Hearts not Heads of Iron (unless you are a Cromwellian)
Besides, an helium filled hat would make you lightheaded... ;) :P
a common misconception
But what if the helium leaked? That would be cool. *speaks in a squeaky voice*
Low chance unless you carry your head upside down. Otherwise the helium will dissipate upwards.
You'll have to ask this guy:
(http://images.wikia.com/farscape/images/1/15/Rygel_puppeteer.png)
:mrgreen:
Ugh! Is that what a head lice looks like??
Oh, Rigel, how I miss thee. A heart of gold, covered in a complete bastard. ;D
WARNING Unsavoury content follows
I am just watching a detective story on TV and the blind man with the guide dog has just got killed, which led me to wonder, in countries where one is obliged to scoop up one's doggy's poops, how would a blind man do this?
Inventive answers allowed.
By smell?
I'm told that some folk's sense of smell is quite... acute. And that they can locate things that way... and a fresh source of "exhaust" ought to be sufficiently odoriferous enough to be detectable.
I would certainly hope he did not have to do this strictly by touch.... or at least, he carries those disposable latex gloves and some plastic baggies...
You know, i've not once thought about how the blind were meant to do this. Maybe if they're walking their dogs, when it stops to do its business, they get close in on the action so they know more accurately where it is, or maybe they are exempt from the law? I'll have to look for that online.
EDIT: Almost the first result - http://puppyintraining.com/who-picks-up-guide-dog-poo/
Hmmm. Still must be quite difficult I would have thought.
Quote from: Griffin NoName on June 23, 2012, 01:03:46 AM
Hmmm. Still must be quite difficult I would have thought.
Maybe, yes, but from what that webpage says, it appears that method makes it far simpler. I thought they'd have come up with something for guide dogs and their blind owners, and this appears to be what i'd say is the simplest method.
Quote from: Roland Deschain on June 22, 2012, 07:09:17 PM
You know, i've not once thought about how the blind were meant to do this. Maybe if they're walking their dogs, when it stops to do its business, they get close in on the action so they know more accurately where it is, or maybe they are exempt from the law? I'll have to look for that online.
EDIT: Almost the first result - http://puppyintraining.com/who-picks-up-guide-dog-poo/
Bloddy clever, I'd say-- all the people I've ever known personally, who were blind, had excellent sense of spatial memory-- for example, when sitting at table, the blind person would have to hunt for the silverware, glasses, plate, etc. Once. After discovering where all this stuff was? They unerringly remembered where it was, for use. I suspect long practice honed their spatial memory to a fine degree (to avoid knocking over glasses, if nothing else).
So, once a guide dog owner knows how far the end of his/her dog is, with respect to where they were touching the animal? It'd be simple enough, to remember where the poo must be deposited, to fish up with a plastic baggie (or other pooper-scooper)
I'd not thought of the spatial awareness that blind people have to function in everyday life. It reminded me of this Family Guy sketch, which although it uses humour, puts across a serious point. This is the only one in English on YouTube that I could find.
[youtube=425,350]8Hhg7wbknr4[/youtube]
What is the ideal distance from a movie screen (in proportion to the size)?
Up close one can see all details but not the full image, too far away and one gets the full image but it gets smaller with distance.
In most cinemas I frequent the last row is the best but in smaller ones it is still a bit too close to the screen. And some very old Berlinian cinemas are very narrow but extremly long, so one needs binoculars from the seats farthest from the screen.
So, where's the optimum?
Using simple trigonometry you can consider your angle of view and the distance to the screen compared to the width of the screen. Assuming an angle of view of 100o, you can form a triangle where the base is the width of the screen and the height is the distance from the screen and use function splitting the triangle in two (to get 2 right triangles), define the angle (50o - 90o = 40o) and calculate a tangent:
tan(40o) = 2L/w
so for a 5m width screen the distance L would be:
L = w tan(40o) / 2
L = 2.1 m
In that particular case you would insure that the edge of the screen is on the very limit of your vision, you can play with both the angle or the width if you want more clearance.
That's elementary geometry and I remember enough of that. The question pointed more towards physiology, i.e. what is the ideal angle for the eye considering area of sharp focus, normal eye movement etc.
An optometrist may be able to answer that one more accurately, I know that the density of cones and rods increases radically at the center and gradually diminishes as you go out and there are slight variations depending on the individual. The angle at which you can read for instance is ~5 - 10o, but you generally are sweeping the area of vision and the brain generates the perception of a full picture.
There may be concrete elements to consider but subjectively I would propose that to enjoy a movie you want to be relatively close to the edge of your visual angle because that would help you to be immersed in the image (which is the argument for IMAX movies). It is quite likely that some people prefers a smaller angle to have a better perception of all elements on the screen, but at the price of detail.
The knack is to work all that out on entering the cinema. Assuming you enter at the back, furthest from the screen, don't forget the screen will look narrower than it really is. ;)
How long can insects, specifically flour moths and their larvae, survive without air?
Would it be a way to fight this pest by simply flooding the larder with inert gas (e.g. nitrogen since this is cheapest)? Or can the tiny critters survive for hours or days (maybe on tiny pockets of remaining/residual oxygen)?
I would say they can survive exactly one day longer than anyone would need to keep the flour sealed away from air.
::)
^ LOL. This is what Sod's Law predicts.
^^ sounds like quantum theory to me
In truth, "sealed" containers seldom are.
For example, "sealed" plastic bags actually breathe a wee bit, due to miniscule flaws in the plastic film, permitting tiny amounts of gas (and water vapor) to transfer back and forth.
Once I learned of this (back when I was still making traditional pop corn, which came in plastic bags), I used to re-hydrate my popping corn in a glass jar with a real, tight-fitting lid. The difference was astounding.
And taught me something about marketing: Orville Reddenbocker's (a premium brand) popping corn was always sold in glass jars back then.... hmmm. And their byline was that more of their kernals popped consistently than the other varieties. Simply a case of how it was stored and shipped? Likely.
But flour is even worse: it's typically shipped and sold in paper containers, which are even worse as preventing gas transmission back and forth.
So to really test the theory, you'd need to put the flour inside a glass or metal container, with a truly air-tight lid. Then have a way to "charge" said container with neutral gas-- but I'd simply use a vacuum pump myself, cheaper, simple and easily available. Pump it down to 30 inches of mercury for about an hour, and you'll effectively remove all air (and most of the moisture too). Then, if you must, you could re-introduce carbon dioxide or nitrogen.
And then... wait and see how long the flour moths and/or their eggs & larvae last.
My bet, is if you do dry it out with a vacuum? That dryness would be the real key to destroying the eggs. Many critters can withstand low (or no) pressure. But few can withstand true zero humidity.
And pumping down a gallon jar for an hour, with a quality vacuum pump will do exactly that to already-pretty-dry flour: very close to zero humidity in there.
Of course, once you open'er up? All bets are off: humidity is like water on the floor: it will automatically seek low (dry) areas and re-introduce itself within seconds. So you'd need to re-vacuum after each opening...
.... meh.
It would be quicker to spread the flour out and zap the bugs with a hammer.
Those moths are actual (reverse) Houdinis. They even get into closed metal boxes (with well-fitting lids) and closed tupperware without making holes.
There is always precisely one moth flying around my bedroom, which is not sealed. How is this possible?
Over here Walmart sells a thing the size and shape of a raquetball racquet that is actually a Bug Zapper. ;D
It's less than $6.
It's immensely satisfying to use... :devil2:
It would take care of your serial moth(s). ::)
Unfortunately this thing won't work inside the larder :mrgreen:
I have seen those over here, but not for years. I try and catch my moth when it flies near me.
I've still got one, but I never bother with it now - too much effort to get up and chase the bug. Cap'nB thinks it's a tennis racquet.
I have a cat.
Any slow-and-low-flying bug is*.... toast, within a day or so. So I never bother... the cat will get it sooner than later.
:)
As for fast-and-high flying bugs? Those usually find their way outside quickly enough, all on their own.
Again, no worries.
:D
_________
* and moths definitely count as low-and-slow. I've never seen one move very quickly. No wonder they are mostly food.... ::)
The large moths tend to fly near the ceilling and both large and small ones extremly erratic making it difficult to catch them on the wing.
My moth flies at medium height.
[Warning: Animal cruelty ahead]
You can buy one of those mid-high power lasers (http://www.wickedlasers.com/krypton)and shoot the bug down...
:mrgreen: :mrgreen: :mrgreen:
Why does the number of teaspoons one has always decrease over time?
The teaspoon goblins sneak in at night and eat them.
Well, if it is silver spoons then air quality (the lack of it) may play a role
Same reason socks lose their pairs...
No - socks are devoured by the washing machine. Teaspoons are eaten by teaspoon goblins.
Quote from: Sibling Zono (anon1mat0) on September 04, 2012, 05:03:05 PM
[Warning: Animal cruelty ahead]
You can buy one of those mid-high power lasers (http://www.wickedlasers.com/krypton)and shoot the bug down...
:mrgreen: :mrgreen: :mrgreen:
Now to find a way to attach them to my frikkin' sharks. ;D
Quote from: Sibling Zono (anon1mat0) on September 04, 2012, 05:03:05 PM
[Warning: Animal cruelty ahead]
You can buy one of those mid-high power lasers (http://www.wickedlasers.com/krypton)and shoot the bug down...
:mrgreen: :mrgreen: :mrgreen:
That thing is frighteningly low-cost, for something with the potential to blind someone from miles away...
... I remember a gross-number of years ago, where an airline nearly crashed on take-off, because some *#^)^ kid was shining a laser pointer into the cockpit windows...
... meh. Too easy for stupid people to get at, IMO.
But I'd love to have one nonetheless-- I could play with the laser bounce array the Apollo astronauts left on the moon (for example)-- all you need is a good laser (like the above), and an electronic timer-switch to time the laser's trip to the moon and back. From there, you can calculate the exact distance (at that moment) betwixt you and the moon (it varies quite a bit, due to orbital wobble, or so I'm told...quite a bit, as measured by feet that is).
Alternatively, once you establish a proper baseline? You could also use it as an altimeter...
... seriously, it would work relatively well, as such things go. Kinda Rube Goldberg, though.
:D
Just a few days ago a youngster over here tried to escape arrest by using a laser pointer on the policeman laying the hand on him. Although the plot failed, the officer had to go to the hospital. By the time it hit the news it was not clear whether his eyes got permanently damaged.
I'm always terrified of those torches and light bulbs that come with instructions not to ever look directly at the light source. I get an impelling desire to disobey which is really difficult to fight. (Like the desire to stand up in a hushed theatre audience and shout^&'~#!!!***%$ !!)
Quote from: Bob in a quantum-state-of-faith on September 05, 2012, 11:00:06 PMToo easy for stupid people to get at, IMO.
The same applies for automatic weapons I'm afraid... >:(
Quote from: Sibling Zono (anon1mat0) on September 06, 2012, 04:45:51 AM
Quote from: Bob in a quantum-state-of-faith on September 05, 2012, 11:00:06 PMToo easy for stupid people to get at, IMO.
The same applies for automatic weapons I'm afraid... >:(
Here in the US, it's rather difficult to obtain weapons of the automatic variety-- sure, you can, but you need special licenses and all that--usually one per weapon, non-transferable, etc.
Semiauto weapons, on the other hand, are dirt-simple to get, pretty much anywhere.
But stupid people will do what they do best-- unfortunately, they all too often do it to someone else first...
... meh.
Quote from: Bob in a quantum-state-of-faith on September 06, 2012, 05:20:45 AM
Quote from: Sibling Zono (anon1mat0) on September 06, 2012, 04:45:51 AM
Quote from: Bob in a quantum-state-of-faith on September 05, 2012, 11:00:06 PMToo easy for stupid people to get at, IMO.
The same applies for automatic weapons I'm afraid... >:(
Here in the US, it's rather difficult to obtain weapons of the automatic variety-- sure, you can, but you need special licenses and all that--usually one per weapon, non-transferable, etc.
Legally, that is. :P
Quote from: Aggie on September 06, 2012, 07:42:33 AM
Legally, that is. :P
Well... if you want to nit-pick.
::)
I agree: enforce the gun laws we already have on the books, and that right there would eliminate the majority of the problem.
But the politicos want to keep slashing the budget so they can give still more benefits to the already-rich.
... after all--these people can afford to hire private armies*... right? So they likely don't care all that much either way [about guns].
----------------
* so-called bodyguards and/or security forces
The thing is that getting a semi-auto is relatively easy and converting it to fully auto is quite easy.
--
As with lasers, the overwhelming majority of users aren't out there causing mayhem with them, but it only takes one pointing at a plane, or worse, to the public of a completely full movie theater.
In most real world situations the difference between a good semi-automatic and a fully automatic is small to nonexistent. I'd even think one would have a higher hit rate with the former. We are talking about shots per second in both cases. And even in the military many armies have completely disabled the rock-n-roll option and limit their infantry soldiers to semi-automatic and 3-round burst. Few amok runners use (or would chose) LMGs to lay suppressive fire.
Quote from: Sibling Zono (anon1mat0) on September 06, 2012, 11:25:35 PM
The thing is that getting a semi-auto is relatively easy and converting it to fully auto is quite easy.
Really? I've no idea one way or another, but I was told getting the conversion parts was difficult--and apt to get you a visit from the ATF.
Not that I wanted to, mind-- I had an opportunity to shoot a 40cal carbine (semi-auto) as if it was a full-auto gun-- that is, pull the trigger as fast as you can, basically simulating a full-auto.
I did not enjoy the experience commiserate with the expense and the tedious time it took to load the magazine.... not to mention, policing up all the spent casings afterward. And that was only about 50 rounds or so.
I cannot imagine the hassle of dealing with a full-auto machine on a routine basis, unless I was filthy rich enough to have a flunky do the scut-work.
Even in First Person shooting-style video games? I tend to avoid the full-auto type of weapons in favor of the slow-fire-but-more-effective types....
... :D ::)
I suppose that's just me, over-thinking it again.
Quote from: Sibling Zono (anon1mat0) on September 06, 2012, 11:25:35 PM
As with lasers, the overwhelming majority of users aren't out there causing mayhem with them, but it only takes one pointing at a plane, or worse, to the public of a completely full movie theater.
Yes, lasers are more Geeky than guns, and most of the idiots who like to pretend that having a gun makes them somehow... "cool" or "powerful", don't see lasers as having the same effect.
Which, when I think about that, is a fantastically good thing.
:D
The potential for mayhem with a modestly powerful laser is many times higher than the most powerful automatic gun (than can be carried by hand, of course).
I won't mention here, some of the ideas I've seen/read about, that a modestly dangerous laser could do at a great distance... (for the sake of sanity if nothing else).
But what the majority of people do not realize, that to get a laser to shine visibly in the air? Requires a great deal of forethought beforehand: you must fill up the air with dust and/or moisture-particles, or that beam is 100% invisible.
In short, there would be zero way of detecting where the beam came from, if it were a 1/2 mile away (for example), and shone into a crowded-something (outdoors).
Makes me wonder how many political assassinations have been committed using one of these things, but the event was put down to something else... due to them not being able to realize the real cause: an infra-red laser beam from a mile away...
... meh.
As I said, it's a good thing the laser is seen as a Geeky toy by the majority of Machismo-types.
:)
_________________________
Edit:
Quote from: Swatopluk on September 06, 2012, 11:54:29 PM
In most real world situations the difference between a good semi-automatic and a fully automatic is small to nonexistent. I'd even think one would have a higher hit rate with the former. We are talking about shots per second in both cases. And even in the military many armies have completely disabled the rock-n-roll option and limit their infantry soldiers to semi-automatic and 3-round burst. Few amok runners use (or would chose) LMGs to lay suppressive fire.
Very astute observation.
To complement Swato's point, it is terribly impractical for a soldier to be hauling large amounts of ammo. The rambo types only happen in movies because no rational spec-ops would do so, nor would they keep their jobs (or heads) for a long time.
OTOH gangs, thugs, warlords, and otherwise criminals, do like automatics not for sound military reasons, but for intimidation, be it submachine guns to full size assault weapons.
It's almost impossible to keep a handheld weapon on full auto on target. The first three shots may hit, the rest tend to go into the ceiling or the blue sky.
That's the reason behind the three round burst. Multiple hits are usually the result of extremly close range (where one could use the weapon as a club as well).
The infamous Tommy gun had to be fitted with an upward vent in later models because the rise of the muzzle was so extreme that mafia hit jobs even at close range failed. I have read that the Ingram Mac-10 (at times very popular because easily to hide) is practically useless without stock and silencer (the latter only for its weight that helps reducing the muzzle rise).
Quote from: Swatopluk on September 08, 2012, 05:27:39 PM
It's almost impossible to keep a handheld weapon on full auto on target. The first three shots may hit, the rest tend to go into the ceiling or the blue sky.
That's the reason behind the three round burst. Multiple hits are usually the result of extremly close range (where one could use the weapon as a club as well).
The infamous Tommy gun had to be fitted with an upward vent in later models because the rise of the muzzle was so extreme that mafia hit jobs even at close range failed. I have read that the Ingram Mac-10 (at times very popular because easily to hide) is practically useless without stock and silencer (the latter only for its weight that helps reducing the muzzle rise).
And? The silencer is too often used as a grip by the off-hand, and being farther from the pivot-point (the other hand) provides more leverage than holding the gun itself, allowing a more effective attempt at keeping it muzzle-level. Of course, by the 2nd or 3rd clip, it'll become hot enough to burn the idiot-user foolish enough to hold it... but no professional soldier would take it that far anyhow, unless he/she was only firing for effect (see next).
But as pointed out, full-auto is pretty useless at killing someone, but has been proven to be quite effective as a psychological weapon-- the
sound of full-auto can (and does) strike fear in humans who know what it means.
The German MG-42 was especially effective in demoralizing allied soldiers through its distinctive sound (like a buzz saw, which may be the reason that the thing came to be known as the Hitler-Saw). If reports are true more than once a single German soldier was able to significantly delay an allied infantry attack by simply letting the voice of his MG be heard. The Americans put effort and money into countering this effect including producing training fillms (possibly rigged) that allegedly showed that the thing was not better than or even inferior to US machine guns. The fact that the US tried to copy it (with moderate success) and that Germany still uses it in only slightly modified form* seems to belie that. Highly effective if used properly but an unbelievable waster of ammo. I wonder, if somebody at the time came up with the idea to use tape recordings instead of the real thing (recorded rattling of tanks was used successfully on several occasions).
*The MG-42 as used in the field was decelerated to 1200 rds/min from the 1800 of the original model (still the barrel has to be changed after 250 shots of rapid fire). The modified post-war model reduced the cadence even further.
When you say 250 shots of rapid fire, do you mean bullets or bursts of firing, and if the latter, exactly how many bullets/how long do you need to qualify as a shot? Big difference there.
In essence, if you keep the trigger pulled and the MG fires without interruption, the barrel should be replaced after 250 shots. I know there were rules for slower fire but I have no numbers available. The barrels were not necessarily 'shot out' but in acute danger of bursting or melting. One risk the MG-42 did not have but other MGs had was overheating of the breech leading to selfignition of ammo (result: continued fire even after releasing the trigger or explosion whith breech open). Every German MG came with asbestos mittens and the barrel of the MG-42 could be replaced in a few seconds using them (other MGs often had to cool completely down before the exchange could be done). Curious detail: In WW1 hidden MG positions were often detected through the clouds of steam hovering above them (those MGs were water cooled and the coolant quickly boiled under heavy use).
So 250 single shots in rapid fire mode. Gotcha. I'd heard of the water-cooled guns. Urine was also used.
Modern versions can tolerate a bit more due to better metallurgy (and it takes a bit longer due to reduced cadence). But if it comes to that you have done something wrong anyway (or the situation is hopeless ;) )
With the possible strength and heat resistance of modern steel used in aircraft turbines, I would imagine that a modern machine gun could take a fair bit of a beating before giving up, although I suppose it may make a weapon far too expensive to make if it were using that form of steel, not to mention far heavier.
The US used stellite coating inside the barrels of the M60. Allegedly that kept the barrel from bursting even when white hot. But then the barrel strength got reduced to save weight and the advantage was essentially lost.
More and more heavy duty pieces on automatic weapons are made of titanium, reducing weight and improving durability, plus the cost of Ti has been coming down, although still only used in top of the line models employed by special forces.
Titanium has a low but non-zero probability to ignite and burn away :mrgreen:
Quote from: Swatopluk on September 11, 2012, 09:14:49 AM
Titanium has a low but non-zero probability to ignite and burn away :mrgreen:
TG some topic drift. It was beginning to feel like LibraLabrat was back !
Quote from: Griffin NoName on September 12, 2012, 02:28:19 AM
Quote from: Swatopluk on September 11, 2012, 09:14:49 AM
Titanium has a low but non-zero probability to ignite and burn away :mrgreen:
TG some topic drift. It was beginning to feel like LibraLabrat was back !
I'd forgotten about him. He's missed, surely. Anyone know where he's at, and how he's doing?
Sorry, no, not me.
Not seen LibraLabRat for a while either. I hope he's ok.
Human's big brain is often attributed to us becoming meat eaters. If that were true why didn't animals (eg. lions) develope big brains?
Quote from: Griffin NoName on September 25, 2012, 06:07:19 AM
Human's big brain is often attributed to us becoming meat eaters. If that were true why didn't animals (eg. lions) develope big brains?
I think they have the cause & effect reversed... we developed larger craniums, and
then discovered we could eat more meat... (as result of being more clever than the meat we were consuming...)
All apes eat meat whenever they can get it; only humans eat it on a daily basis as a matter of routine.
Lions have no need for a 'bigger' brain. Their bodies are fit for their 'job' and their brains are sufficient. They even manage (limited) cooperation.
In general predators seem to be smarter than their typical prey. Those that are not would not be successful enough to flourish longterm.
I am not an expert but I think humans (and maybe chimps) are the only example where the energy demands of the brain actually require dietary adjustment.
I think it is now mainly seen as a positive feedback loop. Higher developed (and thus energy hungry) brains better allow to acquire the necessary fuel (cheap oil breeds SUVs?). Once a critical limit has been passed going back to grass is/was not an option. But 'choosing' this option also led to scaling back on the body side making humans inferior in everything but long distance running. Lions (and tigers and bears*) kept their arsenal and thus can survive (under normal circumstances) with less gray matter.
*the only ones still keeping the vegetarian option, although only the (rather dim) panda went all the way there.
I've heard the argument that control of fire lead to greater brain capacity, as it augments digestion and allows us to eat more difficult foods (fibrous tubers, dodgy meat, etc).
That still suggests that there was an initial intelligence boost, to make us able to use fire.
Predators (both mammal and avian) are smarter than credited, they have to develop complex strategies for hunting and frequently do so in groups, still the smarter species are not fundamental predators (there is a tendency for generalism) and have very complex social lives. IMO humans had a second jump from basic intelligence (jungle ape) to a more demanding savannah environment which forced a quick(er) brain development. That still doesn't answer why the ape (and most primates) was smart on the first place. The same question applies for the other intelligent groups (cetaceans, elephants, crows, parrots, cephalopods), we don't know what pressures enabled said intelligence, and what conditions allow (or prevent) the second jump on those species.
Based on other outlandish evolutionary embellishments, it's possible that human intelligence evolved partly as a sexual attractant; it makes the most sense if this happened in an environmental setting where increased intelligence meant more resources. What starts as a practical consideration can become a marker for overall fitness on its own.
Just as elaborate plumage on male birds takes metabolic power to maintain and implies that the owner is doing well for himself, being smarter at a time where absolute brain capacity was directly linked to intelligence would probably make its owner sexier. We're very socially aware of how smart someone is relative to ourselves, and can roughly estimate intelligence for most people based only a few minutes of conversation. If smart=sexy entered the equation, that could be reason enough for sustained brain-boosting. Throughout history, demonstrations of intellectual ability (poetry, song) have been quite as involved in seduction as demonstrations of athletic ability (dance, sport).
Intelligence is better than the peacock's tail, however, and we've benefited greatly from it. However, it was probably just about getting it on. ;)
That was before intelligence became nerddom and its lack the new attractor.
Back to the question of "why"-- I think it's simple accumulation.
Once the brain-mass is sufficiently large, intelligence emerges automatically, as an emergent function of complex inter-connections possible with a brain-mass of sufficient size.
In short, I think it happens automatically.
The consequences of that, if true, obviously, is that at some point, machine intelligence will emerge on it's own, too. Again, automatically, whether we wanted it or not.
I think Gene Roddenberry missed that bet, in his prediction/imaginary future. He had incredibly sophisticated and complex machines in his world-- but none were self aware, apart from unique (and deliberate) anomalies such as Data. He surmised humans would know how to limit the self-aware function in incredibly complex machines (i.e. deliberately keeping it out).
I think he was wrong-- any computer sophisticated and powerful enough to disassemble an object (or person) at the atomic level, store sufficient information about said disassembly such that it can be transmitted over a distance, and then (remotely too!) re-assemble an exact copy? (or exact enough as makes zero difference from one point to the next) (transporters, obviously)
Such a machine would be self-aware automatically, whether it's designers wished it were or not. There'd be no choice, I think-- the machine would be thinking on a pretty grand scale, and manipulating informational bits on the order of complexity as is the universe itself. There's 1 x 1023 atoms in a given specific space--roughly the size of a liter (if I remember my physics), the "mole" measurement of a gas. In a solid, the volume is considerably smaller. Such that, a human being would consist of many of these "moles" put together. If you factor in that you must also maintain the state of each atom, it's relationship to the adjacent atoms, including the energy states of the various electrons? Each atom needs more than a byte of memory to represent-- in short, the memory-space of the "remembered" human in transport is more complex than the actual human was, originally...
... okay, I've wandered off a bit here, but my point is, I think intelligence is a natural, emergent property of any given neural mass of sufficient density. Is a cockroach intelligent? Certainly, when compared to a rock! And so on up the ladder of complexity-- apes are nearly as intelligent as humans, and the difference is not nearly as vast as we'd love to pretend, either. ::)
I don't think there is a magical threshold, either-- I think it's a pretty smooth curve from ameoba, who's intelligence is entirely held in it's genome-structure up to humans, who's brains are the seat of their intelligences.
The difference seems greater, as when you reach a certain level of intelligence, you can achieve selfless abstract thought-- which in turn, lets you engage in activity that won't see completion in your or your offsprings' foreseeable lifetimes. Such abstraction is what civilizations are made of, after all. But I do not think that the apes are all that less than we, just because they lack such abstractions-- it may be possible to teach it to them, given sufficient time. The evolutionary pressure to "breed" smarter apes/chimps will do the rest, although the project could take thousands of years... (or not, if we learn how to bypass the normal, slow process of natural selection, in favor of direct intervention).
Quote from: Bob in a quantum-state-of-faith on September 25, 2012, 08:56:12 PM
The evolutionary pressure to "breed" smarter apes/chimps will do the rest, although the project could take thousands of years... (or not, if we learn how to bypass the normal, slow process of natural selection, in favor of direct intervention).
We've been doing this for a few thousand years at least, which is much more time than is required. With a concerted program, I'd expect that a hundred years of selective breeding would make a noticeable difference (the chief difficulty is that chimpanzee generation times are ~10 years at a minimum). Human-level brainpower would of course take longer, as you'd need to co-select for females with wide pelvises, although assisted birth could eliminate the problem ensure a population that would have difficult reproducing naturally.
If we ever get to transporter-level technology, this will be a moot point, as a brilliant enough computer will be able to simply assemble any variant of being you could want by assembling new or modified forms instead of simple transcribing of data. The computer, if it had sufficient understanding of neurophysiology, could literally rewire neural pathways to change memories, behaviour, personality, beliefs of a transported being. A transporter is really just an atomic-level 3D printer, isn't it? ???
Quote from: Aggie on September 25, 2012, 09:09:31 PM
.... A transporter is really just an atomic-level 3D printer, isn't it? ???
Indeed it is.
Once that sort of technology is achieved (if it's even possible-- quantum uncertainty may be an impossible barrier), then actual, Hollywood style cloning becomes possible...
... need a copy of yourself? Beam yourself once, then re-send the beam a 2nd time, for an exact copy... who gets what may be a wee bit problematical.
Another thing? Nothing will have any intrinsic value any longer. Nothing. Need more gold? Beam bars of it to your desired location. Need more unobtainium? Reconfigure the transmitting engine to produce it to your specification, even so far as the finished product.
Manufacturing? Gone-- create a prototype, then use the beam to make exact duplicates. You can even fab-up the prototype with the beam, too-- have it lay down to your specs, the device in question. Didn't work out as planned? No problem-- re-transmit it, applying the corrections to the destination.
Special delivery? No problem: a quick communique to the maker, and they'll beam one over in minutes. The
payment process will take more time than manufacture/delivery.
A society that invents matter transmission as per Star Trek, will be a very different one that anything we have now-- money? Meaningless. Farming? Why bother-- use the matter beam to "ingest" a pile of garbage, re-configure the output to be an already-cooked hot dinner for two (or four or eight or even one).
Oooh... too bad... the little kid was hit (and killed) by a runaway car. No problem: he had just beamed home from a visit to gran'ma's yesterday, so re-beaming him a 2nd time, and little Timmy is back... minus a day. No big dealio.
Poor gran'ma's heart is failing? No problemeo-- beam gran'ma back and forth, applying heart-modification such that she has the heart of an 18 year old's. And while we're at it? A new body to match-- even her brain is youthened, you just apply the old interconnections you saved to the new brain, so that no memories/personality is lost. Instant immortality...
... trash/garbage/toxic waste? No big dealio-- you beam the unwanted mass to somewhere else, saving it as inert (but dense--to save space) matter, to be used the next time you need something.
Need fuel? No big deal-- transmat that pile of useless junk mail into fresh fuel cylinders--already charged and ready to go, too.
Seems far-fetched? Well, yeah-- it does. And likely is. Quantum fluctuation and all that.
But we've discovered that something
close enough to a match is the
same as the original.... so even quantum effects may not matter at all.
... of course, there may be entropy effects: poor gran'ma's been beamed one too many times, and her memories are becoming a wee bit scrambled, from accumulating all those minute quantum-level errors ....
::)
Quote from: Bob in a quantum-state-of-faith on September 25, 2012, 10:02:37 PM
... of course, there may be entropy effects: poor gran'ma's been beamed one too many times, and her memories are becoming a wee bit scrambled, from accumulating all those minute quantum-level errors ....
Just a new form of dementia.
Apart from problems with quantum effects energy demands would be enormous for such devices. Take your gold example. Either gold is already there or it has to be synthesized by fusion or fission. Creatio ex nihilo is theoretically possible but who would pay for a cup of tea that costs as much energy to produce as a large nuke yields (1 g matter equivalent is roughly equal to the Hiroshima bomb; the cup of tea would be in the megaton range)?
Duplication of objects from stored material would still require the breaking and forming of chemical bonds on a scale that the pure energy demand would make it economically unfeasible. And no, the energy from formed bonds cannot be simply used to break others.
Quote from: Swatopluk on September 25, 2012, 11:32:19 PM
Apart from problems with quantum effects energy demands would be enormous for such devices. Take your gold example. Either gold is already there or it has to be synthesized by fusion or fission. Creatio ex nihilo is theoretically possible but who would pay for a cup of tea that costs as much energy to produce as a large nuke yields (1 g matter equivalent is roughly equal to the Hiroshima bomb; the cup of tea would be in the megaton range)?
Duplication of objects from stored material would still require the breaking and forming of chemical bonds on a scale that the pure energy demand would make it economically unfeasible. And no, the energy from formed bonds cannot be simply used to break others.
Point.
However, the notion of matter-to-energy, and then energy-to-matter is what we are talking of, with regards to the transmat beam.
Once you have matter-to-energy? You have unlimited energy-- all you want, in fact. So it won't be an issue.
There's plenty of junk/mass out in the OORT clouds to satisfy such energy demands.
Of course, since no process is 100% efficient, there would be waste energy being given off--likely as heat. More than likely they'd need to move the earth back a wee bit from the fire, so's to let it cool down, what with all the waste heat being generated from gran'ma's weekly facelift beaming treatments...
.. ::)
Seriously, there would need to be a way to get rid of the excess energy-of-entropy: you don't want it in the finished product-- it could be... a problem.
"Captain, we are ready to beam up the load of cargo now"
"Okay, it's secure at the given coordinates. Energize."
Unfortunately, the transmat beam was slightly out of kelter, and only had a 99.99999% efficiency rating-- but matter-to-energy and back again is dealing with such huge power demands, the 0.0000001% extra heat was sufficient to incinerate the entire cargo upon arrival...
... oops ...
I can see it now: giant laser beams shooting the waste heat off into space, to cool everything down... it'd be a no-fly zone over each and every transmat beam's location-- the heat-dump laser beams would be outputting multiple-pentawatts of waste power. By beaming it into space, we don't raise the temperature of earth... well, not any more that it would be already.
The choice would be: Vacation in Alaska's sandy resort beaches? Or go swimming in the sultry waters of Antarctica? :-\
Quote from: Griffin NoName on September 04, 2012, 05:32:53 PM
Why does the number of teaspoons one has always decrease over time?
You may recall my question.
I have found some research into the matter reported in the prestigious British Medical Journal (BMJ).
The case of the disappearing teaspoons: longitudinal cohort study of the displacement of teaspoons in an Australian research institute (http://www.bmj.com/content/331/7531/1498)
BMJ2005;331doi: 10.1136/bmj.331.7531.1498(Published 22 December 2005)
Cite this as:BMJ2005;331:1498[/b][/b]
Objectives To determine the overall rate of loss of workplace teaspoons and whether attrition and displacement are correlated with the relative value of the teaspoons or type of tearoom.
Megan S C Lim, research assistant1,
Margaret E Hellard, director1,
Campbell K Aitken, senior research officer1
Burnet Institute
Th abstract is very informative.
:o
Quote from: abstract56 (80%) of the 70 teaspoons disappeared during the study. The half life of the teaspoons was 81 days. The half life of teaspoons in communal tearooms (42 days) was significantly shorter than for those in rooms associated with particular research groups (77 days). The rate of loss was not influenced by the teaspoons' value. The incidence of teaspoon loss over the period of observation was 360.62 per 100 teaspoon years. At this rate, an estimated 250 teaspoons would need to be purchased annually to maintain a practical institute-wide population of 70 teaspoons.
Pity they don't tell how they were lost.
At work I once drilled the handle of a teaspoon and fixed it to the wall on a long chain. It was normally the only teaspoon in the place, yet my colleagues didn't like it at all.
I always kept my own teaspoon at my office.
Quote from: Sibling DavidH on October 08, 2012, 10:07:59 AM
At work I once drilled the handle of a teaspoon and fixed it to the wall on a long chain. It was normally the only teaspoon in the place, yet my colleagues didn't like it at all.
LOL!
Two reasons: [they didn't like it]
1) it reminded them they were actually sharing a spoon amongst themselves.
2) (and more important) they couldn't take it with them (to be subsequently lost...)
:D
Edit: curious-- how'd you drill the spoon? Most stainless isn't very easy to drill, with common tools. I had once modified a spoon with a series of tiny holes all over it's bowl. I was creating a miniature strainer, for tealeaves-- I also reverse bent it so you could use the spoon to push the leaves firmly to the bottom of the cup. I had to use a tungsten-carbide bit to get through the tough stainless. I used a larger one to bevel the edges of the holes on each side (made cleaning easier). I was surprised at how thick the middle of the bowl actually was.
Quote from: Swatopluk on October 08, 2012, 10:37:22 AM
I always kept my own teaspoon at my office.
I did too. ;)
Quote from: Bobhow'd you drill the spoon?
I suppose it wasn't stainless or - as you say - I'd have been all week drilling it. I can't remember now, but I don't remember it giving trouble.
Couldn't you drill it with a diamond tip?
Quote from: Griffin NoName on October 08, 2012, 07:37:36 PM
Couldn't you drill it with a diamond tip?
Quite. But those [diamonds] tend to be ... expensive and slow-going.
I used a tungsten-carbide bit myself-- an alloy who's hardness is second only to diamonds. And a high-speed Dremil tool: 30,000 RPMs can overcome some shortcomings in your drilling tool-- so long as you don't mind burning up the bit, that is... (as would happen with ordinary high-speed steel bits).
Of course, you could always employ an oxy-acetylene cutting torch... kinda problematic for me, though, as my torch makes a flame that's roughly 1/2" in diameter. A wee bit too big for a small spoon's handle, don'cha think? ::)
All I remember was that I drilled a small hole and fastened it to a length of basin-plug type chain using a very small shackle; if I'd used a key ring the swine would have undone it in a moment. The location was the teachers' staff-room, the villains were the sixth-formers (older kids) who would sneak in when the coast was clear.
I agree that a gas axe would be OTT, Bob, but one might be able to solder to a spoon strongly enough.
Quote from: Sibling DavidH on October 09, 2012, 10:27:54 AM
All I remember was that I drilled a small hole and fastened it to a length of basin-plug type chain using a very small shackle; if I'd used a key ring the swine would have undone it in a moment. The location was the teachers' staff-room, the villains were the sixth-formers (older kids) who would sneak in when the coast was clear.
I agree that a gas axe would be OTT, Bob, but one might be able to solder to a spoon strongly enough.
I've never found a solder or brazing alloy that'd stick to stainless steel... they always balled up and refused to "wet" the metal. So I'd resort to epoxy or if I had to have it super-strong, TIG welding (which I cannot do, but know people who do).
I like the shackle idea, though. A stainless screw would work, too-- especially if you use a grinder to round the nut to a cylinder, and apply some Lock-Tite red to the threads.... that stuff is strong enough, the bolt typically breaks before it lets go. I use it on my trailer hitch-bolts (for example).
:devil2: I'm imagining a video of someone trying to un-do a lock-tite fastener with ordinary pliers...
QuoteI've never found a solder or brazing alloy that'd stick to stainless steel.
Good point. BTW DYKT most penknives, opened, have a slot for the blade which make the perfect small shackle key?
Cap'n B's dad has a MIG welder; I keep saying I'm going to learn.
I did not know that, about penknives.
I always carry some sort of knife-- and these days, I carry a folding "box knife" sort-- it opens, locks in place, and uses those disposable "box knife" blades shaped like a trapezoid. One blade has two edges (as it were) available by reversing the blade.
I don't buy the stainless blades, as I find the carbon-steel ones last longer before needing recycling.
Quote from: Bob in a quantum-state-of-faith on October 10, 2012, 01:00:35 PM
I always carry some sort of knife-- and these days, I carry a folding "box knife" sort-- it opens, locks in place, and uses those disposable "box knife" blades shaped like a trapezoid. One blade has two edges (as it were) available by reversing the blade.
Those things are handy, and if you do a lot of random utility work, it's nice to be able to replace the blade as needed.
I rarely carry a pocket knife about town these days (I work with lots of knives, so no need to pack one); when I do, it's usually a small multi-tool with a decent blade. For the bush, I keep a number of blades about, including a lightweight hunting knife and a small but very sharp hatchet (last line of defense against big things with sharp teeth). The machete usually stays in the truck or next to the bed, unless I'm doing yardwork with it.
I used to be a huge fan of the "Swiss Army" knife variety-- usually Victorinox brand, and one with 30 or 40 different functions or so. But when I started doing A/C work, I found those were just not robust enough for what I was asking it to do.
I switched to Leatherman-brand multi-tool, knife, pliers, saw, etc. But again, they just wouldn't hold up to daily, hard use-- I kept breaking them. And at $60-80 a pop, that got expensive, so I gave up on the multitool entirely.
I carried a reasonably high quality folding lock-back knife for quite a while-- 6" to 8" blade, and I liked it. But I increasingly found myself reluctant to use it for fear of chipping the blade, requiring hours on the honing stone to get back to a good edge, and even if I was careful about how I used it, it still was more dull than sharp, most of the time...
... so I finally settled on the current incarnation: the folding, lock-back "box knife". It needs no tools to changeout the blade, it uses standard "box knife" refills, and each blade has double-duty as only 1/2 is exposed at a time. It has a robust aluminum handle, with a steel blade-holding section. A small easy to get-at latch hold the blade in place-- easy to change, but not so easy that you'd accidentally release the blade. If it had a spare storage-space? I'd be perfect-- it's even red, making it easy to spot if laid down or dropped. :)
I don't care for the sliding varieties, even the ones that lock in place-- they are too long in the storage-mode, and typically require a tool to change the blade. Although they almost always have a space for spares.
Since I'm never out in the bush? I don't really need anything all that large for protection. That's a plus and maybe a minus too... ::) :)
I've always been very happy with my Stanley Knife, but then I am possibly less ambitious.
I've got a mini- and a full-size version of Bob's, which is in effect a folding Stanley knife. Trouble is, the blades are so brittle.
Haven't had a problem with brittle-ness. I like the different blades.
Yeah-- brittle blades was my bane too.
After I chipped the edge on yet another high-quality folding lock-back, I switched over to my current one. I had a blue one for about 6 months which I liked well enough, then I found my latest in red (it came in a variety of colors). The blue one I still have, as a backup (in fact, I have a spare one identical to it in the original packaging-- a sale), but it's blade changing mechanism is a bit awkward to do, and sometimes comes unlatched in my pocket-- not a big deal, as it's folded up, preventing the blade from actually falling out and cutting my fingers. But when it came unlatched, pulling the knife and opening it, the blade then falls out-- a minor annoyance, unless I'm up on the top of a ladder-- then it's a major pain. But that was rare enough.
Found the red one, though, it uses a little push-button to release the blade-- and it's recessed when folded, so accidental releases hasn't happened.
I suppose I ought to pick up a 2nd one-- I've learned that having backup tools is not only a good idea, it's essential in my line of work. :)
Oh, looky! A linky to Amazon, with the knife in question-- Husky Utility Knife (http://www.amazon.com/Husky-Utility-Knife-108011/dp/B0026SY730). Woah! $20 bucks????
I paid $8 at the local home improvement store.... that is some markup! Just goes to show, you gotta know your prices on stuff you get everyday.
Thing is, Griffin, the hard, brittle Stanley blades are ideal for what they're meant for - cutting - but I also want a penknife for levering and digging stuff out and other such actions which will snap a Stanley blade every time.
A month ago we arrived in our hotel room to find a complimentary bottle of wine. But no corkscrew. My small, sharp-bladed penknife dug most of the cork out, then I was able to push the rest into the bottle. ;D
Oh see what you mean. Never use my knife for digging. I have other digging instruments. I also have a tiny penknife which is mother of pearl fascia and about 2 cm long, with small but essential features. Very ladylike.
I do carry a camping tool in my notebook bag (the one that houses my Kindle-replacement gadget). It comes apart into two halves, one a spoon & knife, the other a fork. There are also a corkscrew, an awl, a "pipe scraper" (don't know what I'd do with it) and a bottle/can opener.
I mostly use the fork, as I loathe plastic dinnerware. Occasionally, the spoon too. And once in awhile, I want to split my sandwich in half, and out comes the knife-- since I use it only for such things, it remains quite sharp. I've also used it at the Bar-B-Q places to dice up the inevitable raw onion rings they put on the plate as garnish-- I love raw onion, but rather prefer it diced than sliced or in rings.
That handy gadget fits together into a nice folded-up package and slips neatly in the accessory pocket of my notebook case. And I'm always bringing it along, so I have something to read while eating.
Here it is http://www.usefulthings.com/shop/travel/classic-camping-tool.php (http://www.usefulthings.com/shop/travel/classic-camping-tool.php)
(http://www.usefulthings.com/shop/images/classic-camping-tool/classic-camping-tool-1-lg.jpg)
(more pictures at the link)
Here's one from Amazon (http://www.amazon.com/SE-KC5006S-4-Inch-Camping-Detachable/dp/B000XFHJW4/ref=sr_1_2?ie=UTF8&qid=1350083203&sr=8-2&keywords=camping+tool)
Quote from: Bob in a quantum-state-of-faith on October 11, 2012, 10:38:02 PM
Since I'm never out in the bush? I don't really need anything all that large for protection. That's a plus and maybe a minus too... ::) :)
Plus, you're Amrikan, so I suppose a firearm is de rigeur for protection. ::) A hatchet is certainly a last line of defense (I also often pack an air horn and pepper spray), but it comes in handy for other tasks, like cutting down small trees to create bridges over waterways, and it fits nicely on my belt without getting in the way. I used to carry just the lightweight hunting knife, until I got up close with a non-aggressive bear a couple of years ago. The ruff of fur on that bruin's neck convinced me that I would not be able to do much with just a knife in an emergency situation. I prefer a small lightweight dozuki for cutting firewood as it's more efficient for bucking smallish trees, but don't typically pack one unless I'm camping.
With regards to multi-tools, my Leatherman Juice has held up well enough for what I've used it for, but I don't put too much stress on it.
As for eating implements? Spoons are a little difficult to carve without a gouge, but I've managed well enough for thicker foods like oatmeal. Chopsticks are extremely easy to devise with a pocketknife, provided there are some suitable trees or bushes around. ;) I prefer them over forks for many foods.
======
What, approximately, is the maximum concentration of sugar that yeast will tolerate?
What I'm actually after is how much sugar, added to a fermentation, will kill off the yeast and stop the fermentation.
I think that is highly dependent on the yeast and different strains have been developed deliberately with that question in mind.
Google yields almost three million hits for 'sugar tolerance of yeast' lots of them referring to papers describing differrent varieties of yeast under that aspect and some at the top on the topic of their application.
Hard to say, it's spontaneous fermentation by wild yeasts from grapes in the backyard. I'm making grape liqueur (which has been fermenting in the bottle), so I'm planning to add large amounts of sugar. What I need to know is whether a given amount will keep bubbling (undesired) or knock the yeast out of any shape to ferment.
I suppose any fermentation at this point would just up the alcohol level to the point that the booze would kill the yeast. I'm surprised it's below those levels now; I started with vodka and added grapes. Obviously, it pulled out enough grape juice to reduce the alcohol levels significantly (I subsequently mashed in the grapes and then strained off the liquid).
As I recall, roughly 12% is the level of fatal alcohol-- fatal to yeast, obviously-- as that is the rough alcohol level of most wines. Obviously, it varies a bit from yeast to yeast, and with beer as well.
As for sugar concentration? You could take a small sample (half an ounce or so) and double the current concentration and see what happens. And a 2nd sample, with redoubled.
Of course, to be truly scientific, you really need a way to measure the sugar concentration in any given sample, as your bottle is large enough to permit local variations in the liquid's content. And without active stirring or agitation, higher concentrations would settle to the bottom (more dense) and alcohol, being the lightest least dense would tend to rise to the top.
And no, I don't know how to do that easily-- but a hygrometer might work, since you are dealing with a few chemicals here, apart from the multitude of trace elements, which affect flavor, but not overall chemistry.
I was watching several "how it's made" shows last night (eye candy more than anything else), and distillers frequently used a hygrometer to measure alcohol content. I also seem to recall, it's also used to measure salinity in fish tanks? I think this is true. So, if it can measure salt concentration, it should work just as well with sugars I would think.
Of course, the problem here is that the word "sugar" covers a very large range of organic chemicals .... :D And a lot depends on which one(s) you started with, and how "pure" it was, and so forth. I seem to recall reading starches are basically two or more sugars bonded together? (hydrogen bonding? I forget...been years and years) And that some sugars are really two simpler sugars bonded together and... well I remember it's complicated. ::) :mrgreen:
I would imagine, however, that there exists test papers that would permit you to quickly, and accurately measure the sugar concentration, by extracting a drop of liquid and depositing it onto said paper. I know that sugar concentration is an important step in many-many food processing procedures. So much so, I would be totally surprised if there were not a simple and quick test for it somewhere or other. It's just too obvious, not to have been made by someone or other.
Of course, you could utilize a classic, pre-scientific test: the good old human tongue, and taste it. We humans are pretty good at determining the concentrations of sugars in liquid, provided you are speaking of actual, natural sugars and not some artificial thing. :D
And in the end? A taste-test would help you decide if it's what you were wanting anyway. Right? :ROFL:
(sometimes we silly humans can over-think a thing, when a simple solution is both obvious and more than good enough... heh)
Taste is not the issue (sugar to taste is easy to do); it's more that I don't want the bottle exploding. ::)
Boosting the sugar right now would allow any last-minute fermentation to happen; once the yeast have their final run at it, the increased alcohol concentration (some strains can take up to 20%) should do them in. I'd prefer to just dehydrate them outright with sugar. I'd be better to rack it first, I suppose, to get out any residual yeast carcasses. It's pretty murky at the moment.
As for bursting? There are any number of classic ways to "seal" a bottle but still permit pressure to escape. One of the better ones, I always thought, was the S-bend tube, with a small bit of water/liquid trap-- bubbles can creep through the water-trap in the S-bend, but air/contaminants cannot return.
Another classic is a simple plug of cotton batting-- lets it breathe, but filters out dust particles.
I suspect you can easily get the S-trap from your homebrew supply company-- a nice glass one, with a proper cork stopper for the bottle end. Or you could "roll your own" with 1/4" copper tubing (copper is reasonably inert for this purpose) Of course, you cannot see if there is liquid in the trap, rather a downside I'd think.
Lastly, polyethylene or polypropylene tubing is both cheap and inert-- but you'd need to wrap it with stiff wire to make it hold it's S-bend shape. But you could see through it enough to be sure there's liquid in the trap.
Vinyl tubing is also cheap, but I think vinyl can leave aftertaste behind-- I'm not fond of it where food is concerned (not an issue with the poly's above or glass or copper, for that matter).
:)
Finally? A very tight-weave fabric stopper would work too-- roll a strip tightly until it's large enough to stuff into the neck (for example). Or even a wad of nylon stockings--washed first, of course. :D
(http://www.halbmikrotechnik.de/service/chemie/fluessig/federweisser/bilder/fw-gaer-tech.jpg)
http://www.halbmikrotechnik.de/service/chemie/fluessig/federweisser/bilder/fw-gaer-tech.jpg
Of course one should use cork not rubber for the plug.
There is it! Straight out of a 17th or 18th century lab, too. :D
Oh, I'm trying to get it to finish by Christmas. That's why I want to stop fermentation. I've also got some heavy 1.5 L Grolsch bottles with a wire bale that can take some pressure, if I want to keep any carbonation in it. I'm aiming for liqueur; not sure if you can carbonate syurp. Then again, I suppose that's what Coca-Cola does. ::)
You can put some sodium metabisulphite in to stop it, that's what I always used to do. Not much or you'll taste it. As for airlocks, they're very cheap at any wine-making shop - over here, anyway.
I've taken far too much chemistry to want to actually put it into practice (biology was closer to my heart, but not mind). ;)
I made it up to ~20% sugar, and will keep an eye on it. It tastes really nice, like bokbunja ju.
Will be bottling the first attempt at cider shortly...
By what process do we note the absence of something?
Is it just by comparing a mental image with what we actually see and noting a difference?
This is a quantum question and should have a quantum answer.
Quote from: Swatopluk on February 14, 2013, 12:26:17 AM
By what process do we note the absence of something?
Is it just by comparing a mental image with what we actually see and noting a difference?
It must be, no? If one doesn't expect to see something there (or at least consider the possibility that something could be there), one couldn't note an absence.
Swato's suggestion is surely right. If you look at a place where you have reason to expect something to be, and you note its absence by the fact that you can't see it when conditions are such that you should be able to, then you have reason to believe that it's not there.
Of course, for 'see' you may substitute 'hear', 'feel' or whatever.
We had a friend with very little sense of humour. When it was foggy and you couldn't see the hill to the west, we could always wind her up by telling her that it had disappeared, or been stolen.
Related question: Why do we so often think that something is missing, although it is not and the object presumed missing is right in front of you?
Missing from your current mental model I would imagine. You expect it to be somewhere where it isn't according to your immediate perception, which as you should know, isn't completely reliable.
Quote from: Aggie on February 14, 2013, 06:38:14 AM
If one doesn't expect to see something there (or at least consider the possibility that something could be there), one couldn't note an absence.
There is a philosophical vs idiomatic question there, are unicorns
absent from my home? With 'missing' the word necessarily implies that the object in question exists (or existed).
God may be absent, but is he missing?
Quote from: SwatoRelated question: Why do we so often think that something is missing, although it is not and the object presumed missing is right in front of you?
Because we're dozy buggers, not to mention getting old.
Quote from: Swatopluk on February 14, 2013, 12:27:00 PM
Related question: Why do we so often think that something is missing, although it is not and the object presumed missing is right in front of you?
When I've lost something in plain sight it is usually a different colour or shape/etc from my mental picture of it. I am usually cross when I find it: surely I should be pleased?
Quote from: Swatopluk on February 14, 2013, 12:27:00 PM
Related question: Why do we so often think that something is missing, although it is not and the object presumed missing is right in front of you?
I agree with Griffin somewhat; it's largely based on search image. I think we fail to see something right in front of us because we assume that since we're looking for it, it must be obfuscated. The brain obliges our assumption.
But why then, if we very clearly know that the object is there, we so often look past it several times?
Example: a certain book/CD/DVD on a shelf with a plainly visible and readable title. I often search long and without success, although the thing is on the exact shelf were I remembered it to be.
Occasionally the same happens with words in a thesaurus/dictionary.
I'm guessing it has to do with the par of the brain that can't read street signs or building numbers if music is on in the car...
Now here's a question which seems to be related: This morning the eye doc said my previously repaired eye is full of floaters. I know it was, immediately after the op, but I haven't seen any for two weeks or more. I have to suppose my brain is 'tuning them out', but how can it do that with objects which are constantly moving and changing shape?
Because you never focus on them, so your brain learns to ignore them? If I 'think' floaters, I can see them; otherwise, I don't either.
Try reading Oliver Sacks "Hallucinations" ~ :mrgreen:
Not really science............. but can one copyright one's signature?
I'd say yes. There are signatures that are trademarks, e.g. that of Walt Disney.
(http://www.sjmrra.com/disney/images/disney_signature.gif)
http://www.sjmrra.com/disney/images/disney_signature.gif
But trademarks aren't the same as copyright. :confused:
But it means that only the holder may use them, so legal protection is possible. What specific kind is beyond my expertise.
I need some research and/or statistics help on this one:
How do I figure out what percentage of a country's population has a net worth of less than $0? IOW, how many people have more debts than assets?
I'm interested in Canada specifically, but in principal it should be similar to figure it out for other countries.
StatsCan provides some decent data (from 2005) but bases it on "family units":
http://www.statcan.gc.ca/pub/13f0026m/13f0026m2006001-eng.pdf#page=7&zoom=auto,0,73
AFAIK, this leaves out singles and therefore likely is biased to present a rosier picture than might be actually true. I'd expect young singles in their 20's and older single divorcees to be more likely to have a negative net worth, but the statistics appear to exclude these groups. There's good political reasons to focus on family groups (and probably better source data), but it doesn't give me an accurate number of how many people have less than zero.
I found some tidbits for the US (and a calculator that confirms what I suspected: I do fall in the negative net worth category).
I know my net worth - it is beyond rubies ;)
I just worked out in 2014 I should be £136 p.a. better off due to today's budget by the man who's name cannot be said out loud. In reality I will be losing a lot more than that from cuts not mentioned in this budget, which will come into effect also in 2014. Like about £4,000 p.a. - no idea how I shall manage when that happens. :(
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Why aren't tissues (paper handkerchiefs) coloured?
Quote from: Griffin NoName on March 21, 2013, 05:26:42 AM
Why aren't tissues (paper handkerchiefs) coloured?
Some are, but tend to be pastels.
What''s with this around here where one has to answer one's own questions?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I have a gold ring set with three tiny gems. I say gold, but I don't think real gold by the price. Last week I moved it to a finger next to a finger with a silver (or other silver looking metal). Now the gold ring looks silver, and not nearly so pretty. I imagine the two metals reacted with each other. Is there any way I can turn it back into gold (or rather whatever not real gold it was) ????
It's likely that the ring had a thin electroplated layer of gold over it, and has worn off from rubbing against the other ring, assuming it's only that part of it (?). It might need to be replated.
Oh, and me paper handkerchiefs tend to be coloured, but only after use. ;)
It's simple, really. Just become Catholic and take it to Lourdes (http://miracle-witness.blogspot.com/2011/12/golden-rosaries.html).
Or put it into Danziger Goldwasser (http://en.wikipedia.org/wiki/Goldwasser)
Wow that Lourdes thing is amazing. Almost enough to convert me.
Quote from: Griffin NoName on June 20, 2013, 06:40:56 PM
Wow that Lourdes thing is amazing. Almost enough to convert me.
it has converted me... into a slightly more cynical person :(
:giggle:
Remember, you can convert, but if the miracle doesn't happen there are no backsies.
Probably got Conversion Disorder (http://en.wikipedia.org/wiki/Conversion_disorder)
Wasn't that treated with vibrators? :o :mrgreen:
I think it is treated by psychiatrists - are they the same thing ? ;)
Idealy both emanate good vibes
Silly Walks: what is up with them?
This question prompted by two men I saw walking today, although I have observed both examples many times throughout my life.
First: the Manthlete
There must be women who walk like this, but... This person tends to favor 'muscle shirts' and the more over-developed pectoral muscle -- and nipple -- which can be revealed, the better. (May explain why I don't remember seeing women acting thusly!) Chest is carried far forward; arms bent at 45° angles, elbows pointing out to the sides; arms held stiffly away from the body as if the walker is experiencing severe underarm sunburn on top of reckless shaving with a dull razor.
Why do they do this!?!
Second: there's Totally a Playa inside this Husband/Father
Butt remains almost motionless while walking, remarkable in itself. However, the shoulders and upper torso rotate about 30° with each step, usually accompanied by head bobs, like a chicken.
Why do they do this!?!
Obviously written for comedy, but I have been wondering this for decades, so any answers will be much appreciated!
:D
No department of bio-mechanics in your local university? ;) :P
---
I've seen the manthlete once or twice, I imagine they're catching their breath or something, the other one you'll have to record because it sounds quite hard to do.
I am probably guilty of several silly walks... I've been known to balance on a curb, uphill for several kilometers. ::)
The ability to do that is from practicing the Anti-Sloucher (aka the Stick Up The Butt), which involves using the core to keep the spine extended and upright. I got nagged too many times about posture when I was a kid, I guess. I was pleasantly surprised when I tried some free yoga classes last week that it was actually easier than when I last did it regularly (~3 years ago). Some of the hanging off ladders at odd rotations with power tools at arms' length that I've been doing lately probably helped too, but it was nice to see that my assumed self-delusion that keeping yoga principles in mind during one's daily life was equivalent to doing yoga might actually be true.
The silly walk that I don't let out in public is cat-walking on the balls of my feet. I do it around the house to minimize the sound of my footsteps, especially at night. It's also a great calf workout. I hate going to the gym to do results-oriented grunt work, but tweaking my usual way of doing things is easy and painless.
Why, in American films, are teenagers always climbing in and out of their friends' bedroom windows? Doesn't happen in UK films.
I believe there is a scene in one of those immoral plays by one W. Shakespeare, in which exactly that happens, in fact it isn't clear if they consummate their illegal underage marriage in the room of the young lady in question.
Maybe American teenagers are more likely to have been sent to their rooms and have to escape through the windows. Or maybe they are more likely to have slammed their doors in disgust and refuse to come back out through the door than the well-mannered British teens.
I have a friend in the animated cartoon business that used to do a great take-off on the Manthlete walk. (Animators have to have a good sense of physical comedy.) He'd stick his behind way out back, throw his chest forward and sway his 45 degree crooked arms back and forth with each bowlegged step. He called it the Flex Fiercely walk.
In Bavaria the windows thing has its own name: 'Fensterln'. So, if you see a young man carrying a ladder after dark in the more rural parts of Bavaria, he's likely on his way to enter a nubile young women's sleeping chamber on the upper floor through the window. Possible results:
1. He gets thrown out the window by the uninterested or overchaste girl
2. Both leave the way he came in and she will not return before beoming pregnant (and/or getting dropped by the boy)
3. Sexual acts get committed under the parental roof. The boy will hopefully leave (with ladder) before said parents notice.
Quote from: Sibling Zono (anon1mat0) on August 27, 2013, 07:30:31 PM
I believe there is a scene in one of those immoral plays by one W. Shakespeare, in which exactly that happens, in fact it isn't clear if they consummate their illegal underage marriage in the room of the young lady in question.
I've never seen a production where climbing up to the balcony takes place. But I suppose that doesn't mean there isn't one. I don't think the text illuminates on this aspect.
Bavarians are very efficient carrying ladders. Usually there is a tree planted conveniently close to the target bedroom.
Quote from: OpsaHe called it the Flex Fiercely walk.
Perfect descriptor/slash/character name! :)
Quote from: SwatoplukIn Bavaria the windows thing has its own name: 'Fensterln'.
I anticipate this being exported to US markets as
Fensterlnvergnügen.I apologize for mangling your language!
Well, it adds to the realism ;)
50 pages of Easy Questions !!
We breathe in through our noses, and out through our mouths, but how can we breathe out through our mouth when it is closed? We don't see a load of people with their mouthes hanging open, so it must be assumed it is possible to breathe out with the mouth closed, but how?
aside: when I have a migraine I breathe in through my mouth (open) as breathing through my nose is agonising.
Are you saying that you only exhale with your mouth? We exhale through our noses all the time, in fact the overwhelming majority of time unless you have a nasal obstruction, ever further, it may be harder to breath only through our noses if we need more O2 but because exhalation is less aggressive it is possible to get air through your mouth and exhale through your nose, instead of the alternative.
I breathe exclusively through my nose most of the time, inhalation and exhalation. I make a point of this especially during exercise (except swimming).
Then why do all alternative practiitioners say: breathe in, now breathe all the days stale air out through your mouth?
I think that alternative practitioners (regardless of the field they are alternating in) must, by definition, say the opposite of whatever is the current 'norm'. It may or may not turn out to be beneficial for some, all, or none of the population under some, all or no circumstances.
But I could be wrong. ;)
Quote from: Griffin NoName on September 02, 2013, 04:57:05 PM
Then why do all alternative practiitioners say: breathe in, now breathe all the days stale air out through your mouth?
In certain applications (i.e. trying to get relaxed quickly), that method can work. I usually hear this from yoga practitioners during certain parts of the practice. There are a lot of different breathing methods, with a purported range of effects. In and out through the nose is effective for exercise simply because it keeps you at an efficient pace. If you start gasping through your mouth (presuming your nasal passages are clear), you're probably overdoing it. It takes a bit of practice to be comfortable with this.
I went to breathing techniques with my voice and horn teachers and the general idea is that while breathing through your nose is more desirable as a concept (avoids drying your air passage ways), when you need more air - and diaphragm support - you breath through your mouth because you can get more air quicker. In both cases air goes out of your mouth, albeit in a very controlled fashion (the whole point is to be able to make long phrases with a consistent sound quality which depends on a controlled air speed for the most part). If you aren't playing a wind instrument, like say, a violin, both inhalation and exhalation is by force through the nose, in fact conspicuous inhalation through the nose is encouraged because it helps phrasing.
OK, more questions about a subset of "guy" behaviour. Persons of any gender identification are welcome to take a stab at this... A large percent of our client base is male, and a substantial percent of that is blue-collar, red-blooded, gun-totin, pickup-drivin, grizzly beard-growin male. (Not that there's anything wrong with that -- ha!)
[edit -- DISCLAIMER: the following behaviors are not perpetrated by the majority of this demographic!]
Some customers make a beeline to the men's room upon arrival, every single time. I'm thinking, they're on job sites, or traveling between job sites, so 'civilization' may be appreciated, ok. I'm also thinking, several are getting to the age where prostates may be acting up, ok. That does not explain excuse the few who are unfamiliar with how to flush a toilet (going out on a limb here to bet this is the same group which hasn't figured out how to operate the turn signal in their vehicles either). It's the same ones every time, and none of us appreciates having to clean up after them. I'd *like* to refuse to take that roll of plans from them unless they can convince me that they (a) flushed, and (b) washed those grimy paws.
bleah :P
We're also starting the season of layers of thermal shirts, flannel shirts, sweat shirts, and insulated jackets or coveralls. There is a particular odor I call "winter sweat" that surrounds these individuals like a cloud by Spring, after months of outside workin, snow shovelin, beer drinkin in a bar til closin, huntin, etc. Again, okaaaaaay. It does disturb me that this odor is already prevalent around several of these people after a single snowstorm, which leads me to wonder if they ever washed any of these items before putting them away last spring. Are they unfamiliar with the concept of (even weekly?) bathing and laundry, or do they think this is wimmins work, and no self respecting wimmin want to go anywhere near them?
(http://www.millan.net/minimations/anims/stinky.gif)
Finally, this is also the group which seems to have least concerns about industrial grade, public flatulence. The kind that makes your eyes water and your teeth clench to keep from gagging, as they maintain deadpan expressions and missile-lock eye contact while giving extensive directions. Seriously, dude, you were just in the men's room. We saw you go in and we'll have to go in there when you leave and flush it. Can men be that genuinely unaware of their actions? Or (as I believe) are they well aware that they've pinned a woman behind her desk before farting at will, while blocking the doorway -- and either think this is acceptable, or are mentally cracking themselves up? Is there anything that can be said to these bovine specimens that make it clear this is not acceptable which won't get me in trouble?
(http://www.freesmileys.org/smileys/smiley-fart006.gif)
ps: I have considered keeping an gaggingly floral aerosol "room freshener" handy to spray casually and unrelentingly in the air between us with one hand -- also keeping my face unemotionless and maintaining unflinching eye contact -- while writing their instructions with the other hand. I bet I'd get in trouble for that, though. It would be rude.
I suspect you may prefer the oblivious ungulate (who is filthy simply because he wasn't fully potty trained) than the alternative, the aggressive, chauvinistic and misogynistic artiodactyl that is actively trying to annoy you, and that would celebrate if you react in any way as it is an opportunity to put you on your place.
I'd say that those individuals are the product of a more rural environment, but I'm not sure if their urban counterparts (those basement dwelling dweebs that have some sort of allergy to showers) are really preferable.
They sound like Neanderthals - applogies to real Neanderthals..
Lock the toilet, put a large notice on its door saying "Closed due to people not flushing" - and wear a face mask. There are things your employer should not make you put up with.
I suppose I should post some observations about ridiculous behaviors by small percentages of the female population sometime, but they just don't affect me the same way. ::)
artiodactyl -- a new (to me) word! Thanks, sibling zono. :thumbsup:
Quote from: pieces o nine on October 18, 2013, 01:04:05 AM
I suppose I should post some observations about ridiculous behaviors by small percentages of the female population sometime
Like wearing these:
(http://stateschronicle.com/wp-content/uploads/2013/08/high-heels.jpg)
http://stateschronicle.com/wp-content/uploads/2013/08/high-heels.jpg
but it's maybe not just a small percentage ::)
Those are unregistered weapons! :o ;)
I was gonna go with "pepper spray" direct to the face of the fartee... but that'd be too much?
I do like the having a handy floral spray handy, and without batting an eye, liberally spraying on either side of them-- not **directly** in their face as it were...
Too much?
How about having one of those hideous "room deodorizer" things-- you know the one, it's filled with an ugly green liquid, you open the top, and pull it up a bit to release the dragon.
Anyhow, when they let one go? You stop what you're doing-- say "excuse me", and then get out the deoderizer and ostentatiously open the top-- waving it around to either side is optional. Then setting it down directly in front of them-- all without a word.
Then, without missing a beat, "where were we?"
But I really like the pepper spray....
I like the wafter idea Bob. They couldn't prove you were insulting them rather than just being a fanatical smell sprayer type person, which might prevent complaints to the management.
I could whip out my old neopagan censor and my old anglican prayerbook, and "incense"* the customer...
(http://images4.wikia.nocookie.net/__cb20130822153206/xkcd-time/images/7/7f/1eveque.gif)
I command you, unclean spirit, whoever you are, along with all your minions now attacking this servant of [my boss's boss's name]... I cast you out, unclean spirit, along with every Hydrogen Sulfide power of the enemy, every spectre from unclean lunches, and all your fell companions; in the name of [my boss's boss's name]...
~ ~ ~ ~ ~ ~ ~ ~ ~
* that is the correct term for wafting incense about, btw! :giggle:
Hmmm... can you keep a candle and matches handy, and light the candle when needed? The sulphur in the matches is pretty good at neuralizing and covering other odours.
Quote from: Aggie on October 22, 2013, 06:59:03 AM
Hmmm... can you keep a candle and matches handy, and light the candle when needed? The sulphur in the matches is pretty good at neuralizing and covering other odours.
And if he gets really obnoxious? You have hot wax to toss on him... no? Too much?
;)
Quote from: Bob in a quantum-state-of-faith on October 23, 2013, 02:10:37 AM
Quote from: Aggie on October 22, 2013, 06:59:03 AM
Hmmm... can you keep a candle and matches handy, and light the candle when needed? The sulphur in the matches is pretty good at neuralizing and covering other odours.
And if he gets really obnoxious? You have hot wax to toss on him... no? Too much?
;)
Since I work surrounded by paper and combustible materials,
mmmmm, no.
But I like the way you sibguys think. :)
The matches is an old staff-bathroom trick. It's not a particularly beautiful smell, and one still knows what it signifies, but it does effectively mask fecal odour.
Is December 21st (winter solstice) the shortest day flanked by two nights of equal length? If not, is the night before or after the longest? And how about summer solstice?
Quote from: Swatopluk on December 21, 2013, 10:42:16 AM
Is December 21st (winter solstice) the shortest day flanked by two nights of equal length? If not, is the night before or after the longest? And how about summer solstice?
This year the December solstice occurred at 17:11 GMT on 21Dec. so for points North of the equator on the earth's surface about 7 hours West of Greenwich the solstice would occur at midnight giving a single longest night. conversely, 5 hours East of Greenwich the would occur an exactly analogous longest day for southern latitudes. For other longitudes exactly how the solstice is manifested would depend on when it occurred at your local mean time.
If the plural of leaf is leaves, why is the plural of belief beliefs? Is it purely that believes is already in use as a verb? If so, did that use actually pre-date, or co-incide with the definition of the plural version of belief?
I am guessing it has to do with the letter arrangement and use.
The only other word with an "eaf" at the end (as in "leaf") that I can come up with is "sheaf", which is pluralized as "sheaves".
For "ief", as in "belief", there are
"grief"- grieves (verb)
"brief"- briefs (plural)
"chief"- chiefs (plural)
"relief"- relieves (verb) and
"thief"- thieves (plural)
I think there is no logical rule whether the plural goes with f or v.
Tolkien made an explicit note that the form 'dwarves' he preferred aesthetically was unfortunately not the correct one but 'dwarfs'.
I suppose it's a bit like dive, dove, and doved.
Do doves dive? ;)
Doved?! I don't believe I've heard that one before.
"This is what it sounds like
When doves dive..."
COOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
Think I meant dived. I can no longer cope with English.
Drive? Drove, driven?
Dive? Dived. Diver, dove? (as in I dove off that cliff in a fit of insanity.)
And, of course, dovetail.
English is weird, that's for sure-- it's no wonder that some folk just make up names from a seemingly random assortment of characters for their children.
Perhaps they are driven to do so. ;)
How does ear wax work it's way uphill and exit the ear?
Probably by the action of cilia, the little hairs in your ears. By the time you are fifty, the cilia have become the luxuriant, bushy handlebar moustache growing out of your ears; and you start to go deaf. Not a coincidence, I suspect.
So an in-ear shaver would be a good invention?
Quote from: Griffin NoName on May 21, 2014, 01:56:00 AM
So an in-ear shaver would be a good invention?
Indeed and same for the nose (for the latter there are already models on the market)
Is there a preference in ballet for clockwise motions (both of the individual dancers and choreographed groups)?
I am not a true expert on ballet (more of an opera guy) but on several occasions I got the impression that on stage clockwise movements occurred significantly more often than counterclockwise ones unless an asymmetric stage design (placement of ramps and stairs for example) forces moves into the other direction. Coincidence or is it indeed more common and, if yes, why?
I think you are right. When I think of a ballerina spinning on points it is always clockwise. Is this because they always do, or merely a vaguery of my brain. I think it might be like right-handedness - the common default - clockwise is after all how time clocks work. But what if a ballerina were to spin through the earth to Australia from Europe? Would they still be spinning clockwise when they reached Australia?
Isn't it obvious which way she's spinning?
(http://upload.wikimedia.org/wikipedia/commons/2/21/Spinning_Dancer.gif)
It's obvious she needs to put some clothes on.
If no one looks at this page ever again, will she always be spinning?
Quote from: Griffin NoName on June 13, 2014, 11:25:29 PM
If no one looks at this page ever again, will she always be spinning?
Bishop Berkeley? Is that you?
Around... :mrgreen:
With a bit of concentration, I can get her to "spin" in either direction. But I've always been a lucid dreamer, so... maybe that's it.
Of course, I used to practice "flipping" the Lunar maps that National Geographic used to publish alongside Apollo reports... and by that, I mean if you look at the Lunar craters one way, the look like normal craters. But if you look at them another way, the "flip" and appear to be bumps instead.
I spent many childhood hours making them jump in and out...
... which might explain certain things later in life.... heh.
It's like those pictures which if you stare at in a certain way reveal naughty bits.
How is instinct carried out as a process, from genetic information to automated behaviour?
The genetic information is in the brain cells which fire the relevant neurons for that and signaling to the body/being to behave in a certain way.
I suppose I mean, how is it mediated from genetic information to "you shalt do this" i.e. spiders weaving a specific web pattern.
I have a vague idea of how it must work at a hand-waving level (genes code for proteins that trigger certain metabolic and neuronal processes), but what are the details, and is it similar for most complex instinctive behaviors? DNA is the core software, but I'm under the impression that it would be a bit cumbersome to actually work directly with this code in the timespan under which behaviors are carried out. It seems more likely that the sequences would code for hard-wired neural nets which convert specific stimuli to specific actions. It makes sense that this should be possible, as much of our brain's processing structure (such as image processing) is hard-wired and based on structures that are not 'learned' (although the application of how to make sense of them probably involves a significant learning curve in more complex animals).
I've just never seen a detailed theory of this process completely laid out anywhere.... possibly this is because the details were not yet discovered back in my student days, and/or I never progressed far enough in Biology to be exposed to them (3rd year Animal Behaviour was about the closest I would have got to it).
It implies that behaviours are open to direct genetic coding once the field advances far enough... one could hypothetically genetically engineer an animal to behave in a hard-wired manner in given situations. It therefore should be possible to remove some 'free will' in animals or humans by inserting engineered-instinct programs relating to areas that are usually approached via learned behaviour.
It might also be possible to engineer animals to perform certain specific tasks in a non-learned manner, thereby eliminating the training curve required with more intelligent animals. We could, for example, program animals much less intelligent than dogs to perform as sniffers (provided they had similar abilities to smell). How about swarms of genetically engineered roaches or moths that seek out drug or explosive residues, then light up like fireflies in the presence of these compounds? Much cheaper and easier than training a dog, and easy to produce in the millions.
Some parasites/microorganisms already managed that trick and can change the behaviour of the host to the advantage of the 'guest' and detriment of the victim. In particular there are multiple examples of behavioural modicfication leading to increased predation by reducing risk awareness (so the predator can spread the organism further) and/or increased aggressiveness (so the victim spreads it more easily; most prominently: rabies).
I read just recently that there is one parasite/germ affecting humans that acts differently (in opposite manner) on males and females, making the one less risk-aware and the other more risk-averse (I forgot wich for whom).
Most of the mechanisms (as I understand them) work in the same random way as everything else, for instance, if different regions of the brain have more or less development you can see changes in behavior, which in turn can favor the success of the individual in a particular environment, so if a nervous, jumpy, ADHD-like behavior helps a bird survive predation, ADHD-like behavior is selected, that is, the specific behavior isn't encoded but the root causes in brain development are. Given that behavior is the result of a number of different [internal] pressures molded by experience, the original pressures can be defined from the start (ie, how separated identical twins tend to have the same ticks, likes, and outright behaviors regardless of environmental influence) as certain brain structures have more or less development, due to traffic, circulation, or other non understood form of stimuli.
The alternative (which I think is less likely) would be something like a ROM vs RAM kind of thing, that is, pieces of information (ie, memory) that cannot be overwritten by experience (like ROM memory in a computer).
Some of these ROM areas must exist because some behaviours are a bit too specific. E.g. spiders of one species construct the same web but web designs vary greatly between species.
Quote from: Swatopluk on October 20, 2014, 08:18:42 PM
I read just recently that there is one parasite/germ affecting humans that acts differently (in opposite manner) on males and females, making the one less risk-aware and the other more risk-averse (I forgot wich for whom).
Toxoplasma gondii perhaps? I know it can lead to greater risk-taking in those infected with it, and many of the studies have focused on males (we tend to die when we take risks). It's theoretically possible to create a virus that re-programs those infected with it; rabies is a good example. I'm sure someone is working on one that increases consumer spending. :P
Quote from: Sibling Zono (anon1mat0) on October 20, 2014, 08:45:27 PM
Most of the mechanisms (as I understand them) work in the same random way as everything else, for instance, if different regions of the brain have more or less development you can see changes in behavior, which in turn can favor the success of the individual in a particular environment, so if a nervous, jumpy, ADHD-like behavior helps a bird survive predation, ADHD-like behavior is selected, that is, the specific behavior isn't encoded but the root causes in brain development are. Given that behavior is the result of a number of different [internal] pressures molded by experience, the original pressures can be defined from the start (ie, how separated identical twins tend to have the same ticks, likes, and outright behaviors regardless of environmental influence) as certain brain structures have more or less development, due to traffic, circulation, or other non understood form of stimuli.
On an evolutionary basis, this makes sense, and I could see how these brain structures arise as physical units from genetic sub-programs over time.
The very specific ones still have me a bit boggled; I can understand for example how gross behavioural impulses (the urge to bite prey, for example) are mediated from stimuli to execution for animals who learn by experience (start with the base framework and then refine specific neural pathways for the fine motor skills), but in the case of a spider weaving a web or a caterpillar constructing a cocoon, these are not learned behaviours. A spider cannot easily step out of a web and check to see that it's correct, so it takes a very closely coordinated series of motions to create the web. The unit sub-tasks are easy, but there must be an algorithm for the process that determines
if last motion was
this,
then next motion is
that. Is the algorithm held directly in the DNA, or do the genes code for neural connections that constitute the algorithm?
While I have no clue as to the exact process there are certain details that can apply, for instance, it is known that in insects most of the constructions have geometric or fractal properties, which would make sense as the instructions needed to create them don't need to be long or particularly complicated even if the result may be. As for the mechanism proper, there must be a trigger that sets the animal in the programmed task which in turn has to be manifested in the animal's nervous system, possibly in a ROM-kind storage.
While the mechanism mostly applies to primitive nervous systems, it is likely that some of that is retained in higher species (right now I'm thinking on birds nests) but I'm sure that some other more complex mechanisms are at play there (ie, compelling the animal to do something rather than an automaton following a hardcoded program, plus learning via parents/observation).
Why are the vast majority of recordings of Danny Boy (Londonderry Air) made by men when the song is clearly a love song by a female to a male (given that same sex relationships were illegal bla bla bla)?
eDIT
oh wiki on danny boy : Some listeners have interpreted the song to be a message from a parent to a son going off to war or leaving as part of the Irish diaspora.
But still only some.
And
The 1918 version of the sheet music included alternative lyrics ("Eily Dear"), with the instructions that "when sung by a man, the words in italic should be used; the song then becomes "Eily Dear", so that "Danny Boy" is only to be sung by a lady". In spite of this, it is unclear whether this was Weatherly's intent.[
Oh yeah and
In Roy's (Orbison) version, the singer is Danny Boy who is recalling when his father (who has since died) said farewell to him.
Also
Notable recordings including some - long list - is missing Placido Domingo - Mario Lanzo - my two male version favourates, but does include Maureen O'Hara which is my best favourite female version.
But still. The words commonly used seem to me to be more evocative of female to a male.
I agree with you, Griffin, but a good song doesn't need to be kept only to one gender.
Our choir performs it, but we're mainly female; the men in the bass section take up the melody for part of the song. I suppose one could take the perspective of the song being sung over the grave of the (woman) from whose perspective it is written, by a returned lover (just making this up... ).
Actually I have no big objection to a choral version with mixed gender. It''s so different to a solo.
I like your made up reason. The wiki's reasons seem made up to me anyway.
There is a Spaniard pop group called Mecano in which the songs were written by Nacho Cano (a man) and sung by Ana Torroja (a woman) making gender specific lyrics a bit odd, yet Ana's voice is so good that it doesn't really matter.
That is true of Placido Domingo, at least for me, but does not really explain why the artists are by a huge majority male.
The music business has been male dominated as many others in the past but slowly but surely there are more and more female composers for both classical and popular music. I doubt at this point anybody doubts the ability from someone like Bjork to mention one contemporary name.
Does Einstein's Theory of Relativity explain why time appears to speed up the older you get? If so, how?
I don't think so, but here's how I look at it:
The perception of time is relative to your age, because a given unit of time is measured as a proportion of your total lifetime (lived-time). So, when you're six years old, a two-month summer holiday seems extraordinarily long, because it's a significant proportion (2.8%) of your total life* of 72 months. By the time you're sixty, those same two summer months only represent 0.28% of your life, or roughly 6 days of 6-year-old time.
*Say you're born at the start of September, so the end of the school holiday coincides with your 6th birthday
I'm sure it's not all as clean and proportionate as that, but that's the gist of why I think time speeds up with age.
Or perhaps our brains record less information (in the sense of frames per second) as we age. It could be that we're exposed to less new things and learning experiences over time, and our brain perceives long-time** based on this type of marker. When you're young, new and critical experiences happen all the time, but older people have already been exposed to nearly everything they ever will be.
**I can't say that I've noticed a change in the duration of a second or a minute compared to when I was young (short-time), but definitely feel like the weeks and months go by much more quickly (medium- to long-time). I haven't yet noticed a change in how fast the years pass; in fact, although a month feels short, the last year feels very long when I compare who I am now with who I was then. It was a pretty big year for personal growth and change, even though I didn't really 'do' much compared to some years. This may support the latter conjecture regarding experience and time.
The weirdest time-distortions I've experienced were when I was working out of town for extended stretches, and back for short stays. I perceived the two halves of my life as being on different timelines. It was as if the event-time of city life was based on the days I was there, while field-time corresponded with the calendar.
Sometimes I'd think that I'd seen a particular friend or visited a particular restaurant quite recently (say, two weeks ago) because it had been roughly that amount of city-days since it had happened, but would then realize that it was actually closer to two months in realtime. It was as if my time out of town had been cut out of my city timeline entirely.
I have begun to feel that it has something to do with my perception of my mortality.
Statistically speaking I should be a bit above my half life yet time does pass significantly faster now.
Somewhere I read something on the subject but I don't remember where or what.
Perhaps I'm suffering from Alzheimer? :o
Interesting. I was hopng someone would propose that the particles streaming through us become worn and less resistant to light passing through, or something.
I don't go for the x% of our age theory because personaly although I remember time being very slow as a child, I no longer know what that actually felt like so I can't compare. It may be that we do actions slower as we grow old, therefore the same amount of activity fills more minutes/hours so our perception is that time has speeded up. eg. it used to take me about 10 minutes to rise froom bed, dress, coffee and out the house. Now it takes nearer two hours.
I'll agree that how frantic our days are contribute to our sense of time; when you are a child, there seems to be more moments of boredom, and inactivity seems to be more painful (can't sit still). However, as adults, it seems like time goes remarkably fast for the busy as well.
I look at the relative value of time as we age (the x% theory) as similar to our perception of money. When we've not experience large amount of money, small amounts seem more significant. A dollar to a 6-year-old who might have a piggy bank with $20 in it is a much bigger amount of the total than to that 60-year-old with $200,000 in the bank. I've always been amazed at how much one's perception of money changes as one accumulates larger sums (that first $1 in pennies, then $10, $100, $1000 once you've started your first job, $10000, $100000....). A thousand bucks certainly doesn't mean the same thing to me now as it did when I was half this age.
Time is money :mrgreen:
The odd thing for me is that there are many days when I do nothing except rest in bed. I would have assumed this would mean hours and hours of total boredom passing very slowly. The opposite has happened. When I was healthy and frantically busy, time was nowhere near as fast as now.
Y'all I have a daughter who will be 28 on March 1st.
In 3 years I will celebrate the 20th anniversary of my 29th birthday.
My baby daughter will be married 3 years in April.
Halt time! Halt I say!
Quote from: Griffin NoName on January 02, 2015, 08:27:05 PM
oh wiki on danny boy : Some listeners have interpreted the song to be a message from a parent to a son going off to war or leaving as part of the Irish diaspora.
But still only some.
I've been thinking on this (as we're performing it on three consecutive days at the moment) and the parent connection comes to mind. Otherwise, if a man was going off to war, wouldn't he (the soldier) be more likely to end in a grave than the beloved from whose perspective the song is written? It makes more sense from the perspective of an elderly/sickly parent.
Quote from: Aggie on March 16, 2015, 06:52:36 PM
It makes more sense from the perspective of an elderly/sickly parent.
Yes, that makes sense. I think it's the only scenario that does. Especially if they are already booked to go to Switzerland. :mrgreen:
I have always wondered why the sweetheart at home dies first. Answer, it isn't a sweetheart.
Now what if Danny Boy were replaced by Patsy Girl, since we now allow female soldiers to fight. LoL.
How do the contents of a container behave in zero gravity that is mostly filled with water but has maybe 10-15% air? If it is the other way around the liquid forms globules floating in the air but with 90% liquid that would not be possible. Does the liquid stick to the walls of the container or does the air form spherical bubbles? A few big ones or many very small?
Does it matter what liquid is used (water, water with a detergent, mercury...)?
Which way up is the container? :mrgreen:
7-up ;)
If someone should be able to answer that is you Swato...
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I'd expect capillarity to apply to the liquid (ie, hugging the container) and the gas as bubbles but I don't have the math to support that, and I assume it would greatly depend on the nature of the fluids themselves and capacity to interact with each other. I understand the math for bubbles is particularly complex, and have no idea how solubility would apply in this case. :-\
Surface tension will be important (i.e. detergent would change things), but I would think that most of the liquid in the case of pure water would stay connected-ish. A single spherical bubble might be expected in an equilibrium (& zero acceleration/force) state where the adhesion of the liquid to the container was larger than the surface tension of the liquid, as this will give the lowest surface area of interface for the smallest volume of air.
An interesting geometric question indeed. What if the container is cylindrical and the spherical air bubble reaches a diameter approaching that of the cylinder? Will the water recede from that part of the walls or will the air bubble elongate to avoid that? At what point?
Here we have an answer to the case of the free floating spherical liquid into which air is injected.
https://www.youtube.com/watch?v=cXsvy2tBJlU
What time is it?
A deceptively simple question which is actually hard to answer, if in fact it can be answered at all.
It's always Now.
(that's the canonical answer)
And it's right before the future.
Now never is now, there is a delay between perception and reality so we always perceive things [not so] few milliseconds too late.
That does not change anything except for extreme Berkeleyans (esse EST percepi)
When I discussed this with my seven year old grandson he decided his time is a milliisecond behind his father's. (we all have our own time). I think mine is probably a macroyear ahead of myself as it is going so fast it is only a second since it was this time last week.
Why do some people (including myself) get an instant short attack of toothache when biting into something covered with honey or icing (or nutella) even when nothing is wrong with their teeth?
(no such reaction when eating e.g. a spoonful of sugar).
A spoonful of sugar helps the medicine go down (Mary Poppins).
Maybe it is the Overload Principle whereby teeth (enamel) become porus when anticipation is greatest.
May be a temperature differential, I had similar events myself and they also surprise me.
Perhaps you should use an enamel-repairing toothpaste?
Nothing to do with temperature or the state of the teeth. It seems to be a question of sweet in a certain semi-solid (pasty) form. The same concentration of sweet in a different form has no effect at all. From what I know it seems to be a trait of the individual, i.e. some have it, others not (again, it does not matter, whether their teeth are in good shape or not).
It happens to me with Milky Way's chocolate bars, but not always. I have the feeling that it happens when my teeth aren't in the best shape, but I wouldn't be able to tell for sure.
I get that a bit... perhaps it's that those type of sweets are sticky and cling to the enamel, giving a dilution-resistant shot of sweet?
Ok, not really an easy question although being these the frequently used thread I'll write it here.
I was having a conversation with some friends about vinyl vs CDs and the quality of each, and eventually got me thinking on the potential of the vinyl to store information in grooves which has to be limited by the molecular density of the material. In a straight line of one (1) cm how many vinyl molelcules will I find? Is it close to consider each molecule as a point/bit. or the distribution of the material would make it impossible to reach that 1:1 ratio?
Note that I'm not talking about the transfer of information in a vinyl track, which also begs the question if that takes advantage of all the potential in the material?
Trick question... it's a polymer, so I'm not sure what resolution you could get out of it. It's probably able to resolve to a monomer-sized unit, I suppose.
You'd need a very fine needle, and even a tiny speck of dust might be enough to throw it off in that case.
I had wondered why laser turntables were not a going concern, and that's the reason. You can read a vinyl record with a laser, but if it's not absolutely clean it gains noise from bits of debris and dust that a needle would sweep aside.
Something odd happened the other day. I was in the kitchen and suddenly saw light coming and going in the hallway. Thought it was a power surge. But when I went out in the hall I could see the bathroom light was on and the extractor fan was going (linked). The flickering had been the light coming on.
Have I got rats eating the electric cables?
Like this one?
https://www.youtube.com/watch?v=ireQyNQ8lVw
^__^
Now I have a dropping. It is about just over a cm long, curved, black, 2-3mm diameter but halfway between round and flat, very hard, stiff, brittle. Of course, it could be something else entirely. It was close to a rug which has some black tufts but they are not stiff and brittle. Or it could be chocolate from the days when I ate pain de chocolat, but where has it been hiding?
That's a pretty big turd, but I've never had rats around.
Does it taste like chocolate? ;)
Seriously though, was the light and fan switched on previously (i.e. did they come on for no reason or just go off temporarily)?
Quote from: Aggie on August 09, 2017, 04:20:29 AM
That's a pretty big turd, but I've never had rats around.
I don't think it is rat, but that is the most obvious, but I haven't found any more.
Quote from: Aggie on August 09, 2017, 04:20:29 AM
Seriously though, was the light and fan switched on previously (i.e. did they come on for no reason or just go off temporarily)?
I don't think it had been on for days.
I can't see how the light would have been turned on from any action inside the walls (i.e. chewing on wires, etc), unless:
-switch was already on
-a wire to the switch or device was loose already
-something knocked the loose wire back into place
which is all fairly unlikely. Having the whole light and fan go out unexpectedly would be more of a worry regarding rats in the wires.
I'm not sure how to explain it though; it's possible that the circuit was out (blown breaker) and someone reset it, although I'd expect the breaker panel to be in your apartment. Most likely is that the switch was left in a halfway-on-halfway off position and just began making contact. Keep me posted if it does anything else funny.
Thanks Aggie. What we call "The Fuse Box" is inside my flat and I hadn't been anywhere near it. I'd know if a switch were thrown. Light bulbs going can do that.
I guess I have to go with the switch was between off and on. Even that does not leave me feeling happy.
I have a new cleaner - it'll be her last put the light off.
A new question. Why does a teaspoon balanced on top of an open bottle stop the fizz disappearing?