On 7/1/2014 3:43 PM, LizR wrote:
On 2 July 2014 10:16, meekerdb <meeke...@verizon.net
<mailto:meeke...@verizon.net>> wrote:
On 7/1/2014 2:55 PM, LizR wrote:
I agree. As Victor Stenger mentions in "The Comprehensible Cosmos"
causality is
just another word for the 2nd law, and the 2nd law is an emergent result of
the
universe being in a special state - namely expanding. The expansion
determines an
arrow of time via various processes where initially time-symmetric systems
"freeze
out" into bound states (quarks, nuclei, stars etc). This has the effect of
allowing
the entropy ceiling to rise so a system that was originally at thermodynamic
equilibrium is able to move away from it as it cools / expands.
So the question boils down to whether the expansion is a result of
fundamental
physics, or incidental / local. Eternal inflation seems to suggest it's
fundamental
- or does it? Can someone more knowledgeable correct me on that, if
necessary?
If the universe is big sometime and small others then physical time is
probably
going to point to inflation (not deflation).
Absolutely, probably because of a mechanism similar to the one I mentioned above, which
boils down to "more space = more room to do stuff in". I'm not questioning how the
entropy gradient is derived from expansion, that seems fairly obvious, at least to me.
My question is: Does Eternal Inflation make expansion the result of fundamental physics?
E.I. appears to be time asymmetric
It's not asymmetric. In the Carroll-Chen model universes have a minimal point and
"expand" in both directions, as measured in physical time. In coordinate time, it's
universe that contracts to a few Planck volumes and the re-expands. Coordinate time is
just a label in the equations - so you can say they "really" expand, even though the
mathematics are symmetric.
Brent
- indeed, it appears to be /vastly/ time asymmetric, with our local entropy gradient a
pale shadow of the asymmetry built into a field that expands space exponentially
forever. That would, at first sight, appear to be a time asymmetry built into
fundamental physics.
But is it, really? And if so, how come?
But still, the fact that the universe seems to have started in a low
entropy state
needs explanation (c.f. Sean Carroll's "From Eternity to Here").
Obviously EI is one potential explanation for this, with "big bang bubbles" popping out
of the inflaton field, each giving rise to an infinite universe. Each nucleation (I
think it's called) creates a smooth expanding space-time filled with some form of energy
that turns into quarks and leptons when it cools sufficiently, which it does due to the
residual expansion.
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