On Wed, Jan 8, 2014 at 1:58 PM, John Clark <johnkcl...@gmail.com> wrote:

> On Tue, Jan 7, 2014 at 2:59 PM, Jesse Mazer <laserma...@gmail.com> wrote:
> > Well, most physicists already agrees physics is time-symmetric
> I think you would have enormous difficulty finding one single physicist on
> the face of the earth who says time is symmetrical.... well OK,... maybe a
> physicist who just hag a stroke. You could find many that think Quantum
> Mechanics states time is symmetrical, or almost symmetrical.   So much the
> worse for Quantum Mechanics.
I don't know what you mean by "time is symmetrical" if it's intended to be
something separate from T-symmetry (see
https://en.wikipedia.org/wiki/T-symmetry ), which is a specific
mathematical property of laws of physics, as is the closely related
CPT-symmetry (see https://en.wikipedia.org/wiki/CPT_symmetry ), which does
allow for T-symmetry violations but is probably no use in explaining
ordinary macroscopic arrows of time, unless you want to believe that
antimatter objects would have a reverse arrow of time.
T-symmetry/CPT-symmetry aren't just properties of quantum mechanics,
T-symmetry is also seen in all the other main successful physical theories
including general relativity, classical electromagnetism and Newtonian
gravity (I gave a quick conceptual outline of the meaning of T-symmetry in
the second-to-last paragraph of my post at
I think you will find relatively few physicists who expect that any
fundamental theory like quantum gravity will fail to have these
symmetries--by far the most popular explanation for macroscopic arrows of
time is that it's due to the low-entropy boundary condition at the Big Bang
(which itself might have some meta-explanation in a future quantum gravity
theory, like one which involves eternal inflation, see the Sean Carroll
post I linked to earlier at
http://preposterousuniverse.blogspot.com/2004/10/arrow-of-time.html ). Are
you disagreeing with this standard view, and hoping to explain macroscopic
arrows of time (like the fact that we never see broken eggshells
spontaneously reassembling into eggs) in terms of a time-asymmetric theory
of quantum gravity, not the initial conditions at the Big Bang?


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