Easy Questions?

[Sibling Zono (anon1mat0)]

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.

[Aggie]

Ayuh, but you could use microbes to crack it once it was there.  Besides, according to Wikipedia:

Ammonia 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.

[Sibling Zono (anon1mat0)]

True, but it takes millions of years, once there you can add some from time to time to replenish it.
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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).

[Swatopluk]

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.

[Sibling Zono (anon1mat0)]

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.

[Swatopluk]

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

[Griffin NoName]

. 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?

[Aggie]

I have a geometry question: Can an infinitely large space contain an infinite number of infinitely large spaces?

[Sibling DavidH]

Why 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.  

[Swatopluk]

. 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.

[Griffin NoName]

Why do some coaches have upside down tusks?

[Swatopluk]

Those are rearview mirrors that significantly reduce the blind spot compared to the classic side-mounted ones.

[Griffin NoName]

Why do some coaches have upside down tusks?

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 ?    

[Swatopluk]

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.

[Bob in a quantum-state-of-faith]

They look more like insectile-type antenna...