On Thursday, October 24, 2019 at 12:56:29 PM UTC-6, Philip Thrift wrote: > > > > 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 >
Can you answer the question assuming the CI? 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/f3f8f882-907a-40ae-8fcc-fb2632da706f%40googlegroups.com.
