On Wednesday, May 23, 2018 at 2:24:07 AM UTC, Bruce wrote: > > From: <[email protected] <javascript:>> > > > On Wednesday, May 23, 2018 at 1:45:39 AM UTC, Brent wrote: >> >> >> >> On 5/22/2018 5:59 PM, [email protected] wrote: >> >> >> >> On Wednesday, May 23, 2018 at 12:44:06 AM UTC, Brent wrote: >>> >>> >>> >>> On 5/22/2018 3:46 PM, [email protected] wrote: >>> >>> >>> >>> On Tuesday, May 22, 2018 at 10:41:11 PM UTC, [email protected] wrote: >>>> >>>> >>>> >>> I did, but you're avoiding the key point; if the theory is on the right >>> track, and I think it is, quantum measurements are irreversible FAPP. The >>> superposition is converted into mixed states, no interference, and no need >>> for the MWI. >>> >>> >>> You're still not paying attention to the problem. First, the >>> superposition is never converted into mixed states. It *approximates*, >>> FAPP, a mixed state* in some pointer* basis (and not in others). >>> Second, even when you trace over the environmental terms to make the cross >>> terms practically zero (a mathematical, not physical, process) you are left >>> with different outcomes with different probabilities. CI then just says >>> one of them happens. But when did it happen?...when you did the trace >>> operation on the density matrix? >>> >> >> I think the main takeaway from decoherence is that information isn't lost >> to other worlds, but to the environment in THIS world. >> >> >> But that ignores part of the story. The information that is lost to the >> environment is different depending on what the result is. So if by some >> magic you could reverse your world after seeing the result you couldn't get >> back to the initial state because you could not also reverse the "other >> worlds". >> > > What "other worlds"? If they don't exist, why should I be concerned about > them? AG > > > I think you are ignoring the facts of the mathematics of unitary evolution > of the wave function. Under unitary evolution the wave function branches, > one branch or each element of the superposition, which is, one branch for > each possible experimental result. These branches are in the mathematics. > Now you can take all branches as really existing every much as the observed > result exists -- that is the MWI position. Or you can throw them away as > not representing your experimental result -- which is the collapse > position. But in both cases, the evolution of the wave function shows that > there is information in each mathematical branch. If you discard the > branches (collapse) you throw this information away: if you retain the > branches as other worlds, the information becomes inaccessible by > decoherence and partial tracing. > > The situation is the same in either approach. Brent and I are not being > inconsistent, devious, or otherwise tricky by referring to both MWI and CI > approaches -- we are just recognizing the actual mathematics of quantum > mechanics. The mathematics has to be interpreted, and different > interpretations are available for the way in which the information in other > branches is treated. > > Bruce >
Consider this interpretation of the wf, which for simplicity I consider as a superposition of two eigenfunctions, and based on the probability amplitudes represents a 50% probability of each outcome at some point in time. Since the measurement hasn't occurred, where does this information reside? Presumably it all resides in THIS world. As time evolves the probability distribution changes, say to 75-25, and later to 90-10, and so on. All of this information resides in this world since without a measurement occurring, there are no other worlds, and no collapse. Suppose at some point in time, the values changed to 100-0, Isn't 100-0 as good as other pair if they sum to zero? And why would anyone think another world comes into existence because one of the values evolved to 0? I will now define, in answer to one of Brent's questions, when the measurement occurs. I assert it occurs when one of the pair of values equals 0, All throughout all information was in this world. Why would another world come into existence if one of the values happened to be 0? 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 post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
