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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/a02a3935-d3d8-46de-ad3f-62bd5809f26c%40googlegroups.com.
