On Friday, October 19, 2018 at 9:08:47 PM UTC, Brent wrote: > > > > On 10/19/2018 10:59 AM, agrays...@gmail.com <javascript:> wrote: > > > > On Friday, October 19, 2018 at 5:44:10 PM UTC, Brent wrote: >> >> >> >> On 10/19/2018 12:17 AM, agrays...@gmail.com wrote: >> >> *I can see how recoherence is impossible FAPP, but after some time >>> elapses the state of the cat could Dead or Alive; not necessarily the >>> original state, Alive. A*G >>> >>> >>> When recoherence is no longer possible that's a real physical change. >>> The system has evolved. >>> >> >> *Since decoherence is a unitary process, isn't recoherence always >> possible, even if not FAPP? AG* >> >> >> Sure. If you could reverse the outgoing waves and the local universe. >> > > *Since recoherence is always possible, even if astronomically unlikely > like many physical macro processes, why do you make the point that there's > a real physical change when it's no longer possible (which is never)? I > ask because your comment is confusing. AG* > > > That's the real physical change. Outgoing radiation has left at the speed > of light out into an expanding universe; it ain't comin' back. Why is that > confusing? >
*You seem to conflate two concepts; Irreversible FAPP, and Irreversible (aka Absolutely Irreversible, aka Irreversible in Principle). I tend to believe that every unitary process is either easily reversible, or irreversible FAPP (meaning possibly reversible even if hugely improbable). In the case of two closed containers attached to each other, one in vacuum state and the other filled with gas at some temperature, one can imagine all the gas in one container finally equalizing in both containers. That would occur in finite time, but is Irreversible FAPP. In your example above, one can imagine the outgoing photons bending around super dense masses and returning to their original positions or states. So I would say this outcome is Irreversible FAPP, but you say it's Irreversible, meaning Absolutely Irreversible or Irreversible in Principle. So which is it? AG * *The more interesting issue is whether the WF in the Cat experiment, or for an atom with a half life for decay, evolves in time while the box is closed. I say it must evolve because the probability amplitudes are time dependent. What say you? AG* > Brent > -- 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 https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
