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Originally Posted by Jens
There has been some discussion about the problem of entropy in a cosmos that is infinite in time and yet closed in space. I think this is true, and so therefore, anybody proposing a cosmos infinite in time would also have to propose one infinite in space. In an open system, entropy doesn't apply. I know this is a bit abstract, but there are two questions I have.
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"Open systems" can be treated within equilibrium thermodynamics.
Do a search for
canonical and
grand-canonical distribution within statistical mechanics.
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Originally Posted by Jens
First, how would entropy work in an open system? Would the system be constantly becoming closer to entropy, without every reaching it, or would it be meaningless even to speak of entropy?
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"Open system" means that the system is in contact with another system.
So it can exchange entropy with that other system.
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Originally Posted by Jens
The second is a bit more concrete. It seems to me that the cosmological redshift would be a problem in such a cosmos.
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Why?
Before proposing solutions, you need to make clear what the problem is.
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Originally Posted by Jens
I can think of three solutions:
(1) the redshift is not a Doppler redshift.
(2) the redshift is a Doppler redshift, but is only a local phenomenon (I think that Eric Lerner adopted this position).
(3) the redshift is a Doppler redshift, but has something to do with an expansion or contraction of space itself.
The question I have in this case concerns the third option. Would it be possible, in an infinitely sized and timed cosmos, to have a Doppler redshift based on a change in space itself? On one hand, it seems contradictory -- how can everything be expanding in an infinitely large universe?
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As I said, you have to explain to make sure there is a problem first.
However, on cosmological scales, one has to use General Relativity, and I don't know whether or how thermodynamics is treated within that framework.
EDIT to fix tags.