Darren New nous apporta ses lumieres en ce 2008/01/03 11:59:
> Warp wrote:
>> Darren New <dne### [at] sanrrcom> wrote:
>>> Now, if space expanded and gravity pulled everything back together, 
>>> that makes sense. But that still doesn't answer the question of 
>>> whether (for example) a brick floating in intergalactic space would 
>>> be 10% bigger if given enough time.
>>
>>   I don't think the brick would expand because forces which are much
>> stronger than gravity are keeping it together.
> 
> In other words, space expands, but then the brick collapses again? Sure, 
> it's possible. It still doesn't explain why space expands but the matter 
> in it doesn't. It's like saying "time slows down, but the spring in the 
> clock keeps it running the same speed". :-)
> 
> I don't think this works for celestial objects. If you added space 
> between the sun and the earth without slowing the orbit of the earth (in 
> absolute velocity terms), you'd make an unstable system where the earth 
> would tend to move even farther from the sun.
> 
Space expand where the mater density is under a treshold value. The very diffuse 
gases and relative proximity from stars inside a galaxie prevent space from 
expanding. Between galaxies, there is MUCH less gas and no stars, so, there is 
not enough mater to "hold space in place".
The Andromeda galaxi is moving toward us as it is close enough for the mutual 
gravitational pull to overcome the very weak spacial expantion in the area. The 
mater density in the local group is high enough to, maby almost, maybe totaly, 
cancel the expantion.

-- 
Alain
-------------------------------------------------
You know you've been raytracing too long when you downloaded and printed the 
Renderman Interface documentation, so you'd have a little light reading to take 
on holiday.
Alex McLeod a.k.a. Giant Robot Messiah

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