On Monday, October 14, 2019 at 10:51:03 AM UTC-6, Brent wrote: > > > On 10/13/2019 9:10 PM, Alan Grayson wrote: > > On Sunday, October 13, 2019 at 5:50:35 PM UTC-6, Brent wrote: >> >> >> >> On 10/13/2019 1:08 PM, Alan Grayson wrote: >> > What are YOU talking about? I just made a GUESS about the decoherence >> > time! Whatever it is, it doesn't change my conclusion. If there's a >> > uncertainty in time, are you claiming the cat can be alive and dead >> > during any duration? Is this what decoherence theory offers? AG >> >> Yes, part of the cat can be alive and part dead over a period seconds. >> Or looked at another way, there is a transistion period in which the cat >> is both alive and dead. >> >> But the main point is that this time had nothing to do with >> Schroedinger's argument (he knew perfectly well the time of death was >> vague); his argument was that Bohr's interpretation implied that the cat >> was in a super-position of alive and dead from the time the box was >> closed until someone looked in. >> >> Brent >> > > Agreed. Without decoherence, the cat would be in a superposition of > alive and dead from the time the box was closed until someone opened > it. With decoherence, it would be in that superposition for a very short > time, the decoherence time, when it would be in state, |decayed>|dead> > or |undecayed> |alive> before the box was opened, provided it was > opened after the decoherence time. So, as I see it, decoherence just > moves the "collapse" earlier, before the box is opened, and does not > resolve S's problem with superposition. > > > True, but it resolves the problem about whether conscious observers are > necessary to "collapse" the wave function (or split the world). >
I think Feynman answer this question before the advent of decoherence theory. I recall reading his comments that an instrument was sufficient for observing a double slit experiment, and even destroying the interference if rigged to determine which-way. AG The idea of decoherence is that, it not carefully isolated, systems are > continuously "monitored" by the environment and so act classically. > > Here's a good analysis which casts the Schroedinger cat story into a > double slit-experiment. > > https://arxiv.org/pdf/1405.7612.pdf > > The cause of the problem, or > paradox if you will, is the superposition interpretation of the radioactive > source. AG > > > Yes, that's the problem. The radioactive nucleus is effectively isolated > until it decays, after which it is not isolated...it has interacted with > the detector. So in the MWI the system is splitting continuously into the > branch were the atom hasn't decayed and the branch where is has just > decayed and interacted with the environment. The atom is in a > superposition of decayed and not decayed with amplitudes varying in time: > psi = sqrt[exp(-at)]|not decayed> +sqrt[1-expt(-at)]|decayed> . > But isn't this superposition, interpreted to mean the source is in both states simultaneously before measurement, responsible for the paradox of a cat which is alive and dead simultaneously, even if for a very short time if decoherence is considered? If so, isn't this sufficient to question the validity of said interpretation? 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 view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/a02a3935-d3d8-46de-ad3f-62bd5809f26c%40googlegroups.com.
