On Monday, October 21, 2019 at 12:03:20 AM UTC-6, Brent wrote: > > > On 10/20/2019 10:46 PM, Alan Grayson wrote: > > On Sunday, October 20, 2019 at 6:35:10 PM UTC-6, Brent wrote: >> >> >> On 10/20/2019 4:58 PM, Alan Grayson wrote: >> >> On Sunday, October 20, 2019 at 11:35:13 AM UTC-6, Brent wrote: >>> >>> >>> On 10/19/2019 6:56 PM, Alan Grayson wrote: >>> >>> Sean says the decoherence time is 10^(-20) sec. So when the box is >>>> closed, the cat is in a superposition of alive and dead during that time >>>> interval, assuming the decay hasn't happened. If that's the case, I don't >>>> see how decoherence solves the paradox, unless we can assume an initial >>>> condition where the probability of one component of the superposition, >>>> that >>>> the cat is dead, is zero. Maybe this is the solution. What do you think? AG >>>> >>> >>> Maybe this is an easier question; after decoherence, assuming the >>> radioactive source hasn't decayed, what is the wf of the cat? Is the cat >>> in a mixed state, alive or dead with some probabIlity for each? AG >>> >>> >>> You can't "assume the radioactive source hasn't decayed". The point >>> Schroedinger's thought experiment is that when the box is closed you don't >>> know whether or not it has decayed and so it is in a superposition of >>> decayed and not-decayed and the cat is correlated with these states, so it >>> is also in a superposition of dead and alive. >>> >>> Brent >>> >> >> I thought you might say this. OK, then what function does decoherence >> have in possibly solving the apparent paradox of a cat alive and dead >> simultaneously. TIA, AG >> >> >> It doesn't necessarily solve "that problem". Rather it shows why you can >> never detect such a state, assuming you buy Zurek's idea of envariance. >> One way to look at it is it's the answer to Heisenberg's question: Where is >> the cut between the quantum and the classical? Once envriance has acted, >> then the result is classical, i.e. you can ignore the other possibilities >> and renormalize the wave function. >> >> Brent >> > > Woudn't you agree that if the system, in the case a cat, goes classical > after 10^(-20) sec, its state must be a mixture at that point in time even > if the box hasn't been opened? AG > > > In MWI it's only a mixture FAPP. But if you haven't opened the box (and > Schroedinger was assuming an ideal box) you don't know whether the cat has > "gone classical" or not. So your representation of its state is still a > superposition. That's the QBist interpretation. The wf is just what you > know about the system. >
Please remind me; if the wf is a *superposition* before the box is opened, what exactly does this mean? That is, what does *interference* mean in this circumstance? TIA, AG -- 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/590ba06d-d5d5-479c-b4ee-5eb46fd70469%40googlegroups.com.
