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, 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.
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.
I have not seen your arguments for this, being new to the list, but the
expansion of the universe is a universal consequence of general
relativity. So it is built into the laws of physics, and has nothing to
do with whether or not there ever was a period of rapid inflation.
The AoT comes from the third law of thermodynamics and has little to do
with the expansion of the universe. Entropy increases in the same
direction as the expansion solely because the universe 'began' in a
state of very low entropy. (The Past Hypothesis).
Bruce
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