On 9 January 2014 07:58, 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.
>

The equations of Newtonian dynamics are time-symmetric, similarly for
relativity (both SR and GR - even gravitational collapse is reversible
according to the equations) - and quantum mechanics is, too. The only thing
in the entirety f physics that isn't based on time symmetric equations is
thermodynamics, which most physicists agree is an emergent phenomenon, due
to a special initial arrangement of the components of the universe coupled
with the likelihood that they will come to occupy more probable states over
time..

The second law of thermodynamics is based on the argument that a system in
a low entropy (i.e. improbable) state will head towards a high entropy
(i.e. more probable) state through the statistical result of random
movements, because there are by definition far more probable states than
improbable ones. This assumes the dynamical interactions involved are
time-symmetric, since otherwise there would be no need for this argument -
the universe would head that way for some other reason, due to some
built-in time asymmetry. Since there is no such known time asymmetry,
thermodynamics relies on a statistical argument and an improbable initial
state. This was all explained by Boltzmann about 140 years ago.

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