LizR wrote:
As I recall it, Vic later recanted his earlier idea that the AoT reversed if the universe began to re-contract.I think that was Hawking.
You are probably right. Although I think several people played with the idea.
I think it was Gold who proposed the idea of a universe where the AOT reverses in contraction phase. It's a logical outcome of view that AOT derives from expansion, although there may be some symmetry breaking that forces one "pole" of the universe to be the bang and one the crunch. Plus gravitational collapse appears to create a separate AOT that messes with the whole thing (smooth "initial" state and chaotic "final" one - something to do with the Ricci and Weyl tensors or something, Brent will tell me I hope!)
Penrose makes a lot of the asymmetry in a closed universe that starts smooth and becomes very clumpy towards the end as more and more black holes are formed -- the natural endpoint of relentlessly increasing entropy. However, as with a lot of things, the discovery of dark energy has pushed closed, re-contracting universes out of fashion.
No, my main problem with identifying the expansion of the universe as the origin of the arrow of time is that the expansion of the universe really has essential zero impact on the everyday physics of our experience, but we see a consistent AoT associated with increasing entropy in every phenomenon of our everyday experience. Sure, what happened in the early universe has had lasting consequences for our everyday life, but any connection with the expansion is too remote to provide a plausible explanation of the consistency of our experience of time. So the increase of entropy itself -- whose universality is easily understood -- is itself the origin of the AoT.
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