meekerdb wrote:
On 11/6/2014 3:15 PM, LizR wrote:
On 7 November 2014 09:56, meekerdb <[email protected]
<mailto:[email protected]>> wrote:
I'd say that expansion of the universe is almost necessary, not
contingent. The AoT has to point in the direction of entropy
increase and in almost all models that's correlated to the
expansion of the universe. If it is bigger at one time than at
another then the AoT will point toward the bigger end. I say
"almost" because there are some ways around it. If the universe
recontracts the AoT will probably continue to point toward the Big
Crunch, at least until the total entropy equals the Bekenstein
bound. Or on the other possibility, L.S. Schulmann has written a
nice little book about his investigation of universes in which the
AoT reverses so it always points to the biggest phase of the universe.
Yes, that is indeed exactly the position I have long argued for on
this very forum.
To summarise my argument, which has at times been vigorously opposed,
I think by you amongst others,
Not me. I helped edit Vic Stenger's books that presented exactly that view.
but not yet actually shot down (kaon decay comes closest, but doesn't
appear to be very important in generating the AOT, although it's
possible it actually had/has a pivotal role we're unaware of).
a) the universe is expanding for some reason, possibly necessary in
the sense of being built into the laws of physics (e.g. as a result of
eternal inflation ... perhaps?) - or perhaps contingent, that is to
say not mandated by the laws of physics, but maybe the result of some
symmetry breaking etc.
You seem to overlook that the "expansion" is very likely just
tautological, i.e. it is nomologically necessary that the AoT points in
the direction of bigger.
No, it points in the direction of higher entropy. As I recall it, Vic
later recanted his earlier idea that the AoT reversed if the universe
began to re-contract.
Anyway, that is purely academic. With with known magnitude of dark
energy, the universe will expand for ever, even if it is technically
closed (k = +1).
Bruce
b) all the other things regarded as the AOT emerge from (a). I have
given details of this at some length on previous occasions, but
briefly it's that various bound states (nucleons, galaxies etc) can
emerge from the cooling caused by the universal expansion.
Right. Because the universe expanded very rapidly it is very far from
equilibrium. The actual entropy is at least 22 orders of magnitude
smaller than the maximum possible entropy. Being far from equilibrium
leads to complex structures.
Brent
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