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 http://www.mail-archive.com/everything-list@googlegroups.com/msg45152.html). I think you will find relatively few physicists who expect that any new 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? Jesse -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
