On Tuesday, October 23, 2018 at 6:41:06 AM UTC, scerir wrote: > > > Il 22 ottobre 2018 alle 23.20 [email protected] <javascript:> ha > scritto: > > > > On Saturday, October 20, 2018 at 5:39:28 PM UTC, [email protected] > wrote: > > > > On Friday, October 19, 2018 at 9:08:47 PM UTC, Brent wrote: > > > > On 10/19/2018 10:59 AM, [email protected] wrote: > > > > On Friday, October 19, 2018 at 5:44:10 PM UTC, Brent wrote: > > > > On 10/19/2018 12:17 AM, [email protected] 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* > > > *Seriously; if the wf for a radioactive atom evolves in time, why would > placing it in a box change that (or do I misunderstand what you and Bruce > are claiming)? AG * > > *The original 'cat' was, of course, Einstein's 'gunpowder' paradox.* > > *'The system is a substance in chemically unstable equilibrium, perhaps a > charge of gunpowder that, by means of intrinsic forces, can spontaneously > combust, and where the average life span of the whole setup is a year. In > principle this can quite easily be represented quantum-mechanically. In the > beginning the psi-function characterizes a reasonably well-defined > macroscopic state. But, according to your equation [i.e., the Schrödinger > equation], after the course of a year this is no longer the case. Rather, > the psi-function then describes a sort of blend of not-yet and > already-exploded systems. Through no art of interpretation can this > psi-function be turned into an adequate description of a real state of > affairs; in reality there is no intermediary between exploded and > not-exploded.' * > >
> *Letter from Einstein to Schrödinger, dated 8 August 1935. in Fine, A. The > Shaky Game: Einstein, Realism, and the Quantum Theory, University of > Chicago Press, Chicago (1986). Letter from Einstein to Schrödinger, dated 8 > August 1935.* > *Just to be clear; when I asserted that the wf for a radioactive source or Schroedinger's Cat evolves when placed in a box which is then closed, I did NOT mean the two state system is ever in both state simultaneously; rather, that the probability of being in either state changes with time. 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 [email protected] <javascript:>. > To post to this group, send email to [email protected] > <javascript:>. > Visit this group at https://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. > > -- 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
