On Monday, October 28, 2019 at 5:37:54 AM UTC-6, Bruno Marchal wrote: > > > On 26 Oct 2019, at 22:15, Alan Grayson <[email protected] <javascript:>> > wrote: > > > > On Thursday, October 24, 2019 at 4:53:00 PM UTC-6, Philip Thrift wrote: >> >> On Thursday, October 24, 2019 at 5:07:34 PM UTC-5, Alan Grayson wrote: >>> >>> 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 >>> >> >> >> >> Just translate this into "CI", in whatever terms you like. It gives the >> same answers, so what difference does it make? >> >> *The probability P for an event to occur is given by the square of the >> complex magnitude of a quantum amplitude for the event, Q. The quantum >> amplitude Q associated with an event is the sum of the amplitudes >> associated with every history leading to the event.* >> >> [This] specifies how probabilities are to be computed. *This item builds >> the concept of superposition, and thus the possibility of quantum >> interference, directly into the formulation.* Specifying that the >> probability for an event is given as the magnitude-squared of a sum made >> from complex numbers, allows for negative, positive and intermediate >> interference effects. This part of the formulation thus builds the >> description of experiments such as the two-slit experiment directly into >> the formulation. A history is a sequence of fundamental processes leading >> to the the event in question. >> >> http://muchomas.lassp.cornell.edu/8.04/Lecs/lec_FeynmanDiagrams/node3.html >> >> >> @philipthrift >> > > Sorry, I really don't get it. > > > Nobody does, really. Even if the mechanist know the why, the how will > still delude us for long. Like many said; to understand QM is to understand > that there is a big metaphysical problem there. > > > For me "interference" refers to waves which cross each other and add their > amplitudes, positively and negatively. > > > OK. > > > Why, if we give a probability interpretation to the amplitudes, does this > have anything to do with interference, particularly for a wf for S's cat > which is entangled with the wf of a radioactive source? AG > > > > Because if we send just one particle, we can predict some place where we > will with certainty not find the particle, so that we have to take into > account the wave “associated” to one single particle. >
That's what I did; assume a single UNOBSERVED particle acts as a wave and interferes with itself as two waves emerge from two slits, which will sometimes result in 100% destructive interference. But I have to consider whether this model applies to C60. Not sure of that at this time. AG Now, EPR Bell, but already Einstein at the Solvay congress in 1927, > explains why a mechanical/physical association of the particles with the > wave (like with hidden variable) will not do, without adding FTL actions, > or introducing super-determinism, or killing Realism in Physics. > Keep in mind that the wave I have been referring to, is a probability wave, not a physical wave. AG > > Yes, wave interfere and that is the problem when the wave seems to > describe either our own knowledge/ignorance, or a single particles. There > are less problem, and perhaps no serious problem at all, when we accept > that the physicists obeys to the wave formalism too, in which case we get > coherent set of histories, like Mechanism predicted. In that case we can > understand that the laws of physics originates in the statistics on all > relative computations. > > Bruno > > > > > > > > > > -- > 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] <javascript:>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/c3418bf6-58f5-41a6-862f-8f5337c9115f%40googlegroups.com > > <https://groups.google.com/d/msgid/everything-list/c3418bf6-58f5-41a6-862f-8f5337c9115f%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > > -- 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/a99804d2-e79e-40ce-aee5-7fad0b873573%40googlegroups.com.
