On Sun, Jan 12, 2014 at 6:41 PM, LizR <lizj...@gmail.com> wrote: > > >>> "Retro-causality" (time symmetry is a better term) only exists at the >>> quantum level. >>> >> >> >> Why? Where is the dividing line? And with a Schrodinger's Cat type >> device a quantum event can easily be magnified to a macro-event as large as >> desired, you could connect it up to an H-bomb. >> > > > The dividing line appears to be roughly where decoherence occurs. > Basically anything above a single quantum entity engaged in a carefully > controlled interaction is liable to get its time symmetric properties > washed out by interactions with other particles >
The nucleus of an atom is tiny even by atomic standards so it is certainly at the quantum level, and in its natural state of existing inside a huge chunk of irregular gyrating matter this tiny thing is constantly subject to the slings and arrows of outrageous fortune from an astronomical number of other clumsy atoms; and yet the half life of Bismuth 209 is 1.9 * 10^19 years. Why? >> It's just a fact, if time were symmetrical then you'd be just as good at >> predicting the future as you are at remembering the past, so you'd know the >> outcome of an experiment before you performed it just as well as you >> remember setting up the apparatus. But this is not the way things are >> because the second law exists. And the second law exists because of low >> entropy initial conditions. And I don't know why there were low entropy >> initial conditions. >> > > > OK. So the above statement of yours about predicting the future is still > false, > Yes it's false, I don't think this will come as a great news flash but the truth is we're not as good at predicting the future as we are at remembering the past. And the reason we're not is that time is not symmetrical. > To recap briefly -- the laws of physics are time symmetrical, > Yes, the fundamental laws of physics, the ones we know anyway, seem to be time symmetrical. But that doesn't mean that time is symmetrical. > and most particle interactions are constrained by boundary conditions. > Yes, and that is why time is NOT symmetrical. John K Clark -- 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.
