On Thursday, October 24, 2019 at 9:27:14 AM UTC-5, Alan Grayson wrote: > > > > On Monday, October 21, 2019 at 6:21:26 PM UTC-6, Alan Grayson wrote: >> >> >> 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 >> > > Please indulge me on this. At this point I have no clue what superposition > and/or interference means in this context. TIA, AG >
All these are couched in the vocabulary of the formulation and interpretation of the theory one begins with, and so they have ambiguous meanings. @philipthrift -- 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/3513a8ac-6595-4fde-92d4-fee610a33d33%40googlegroups.com.
