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 -- 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/e9eb7fe2-d668-4a55-8d4b-6020a095663d%40googlegroups.com.
