On Sunday, November 4, 2018 at 1:42:49 PM UTC-6, agrays...@gmail.com wrote: > > > > On Sunday, November 4, 2018 at 3:01:50 PM UTC, Philip Thrift wrote: >> >> >> >> On Sunday, November 4, 2018 at 7:27:12 AM UTC-6, agrays...@gmail.com >> wrote: >>> >>> >>> >>> On Sunday, November 4, 2018 at 1:05:36 AM UTC, Philip Thrift wrote: >>>> >>>> >>>> >>>> On Saturday, November 3, 2018 at 6:21:18 PM UTC-5, agrays...@gmail.com >>>> wrote: >>>>> >>>>> >>>>> >>>>> On Saturday, November 3, 2018 at 9:33:54 PM UTC, Philip Thrift wrote: >>>>>> >>>>>> >>>>>> >>>>>> On Saturday, November 3, 2018 at 3:50:30 PM UTC-5, >>>>>> agrays...@gmail.com wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> On Thursday, November 1, 2018 at 11:22:46 PM UTC, Pierz wrote: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On Monday, October 15, 2018 at 9:40:39 PM UTC+11, >>>>>>>> agrays...@gmail.com wrote: >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> On Sunday, October 14, 2018 at 5:08:42 PM UTC, smitra wrote: >>>>>>>>>> >>>>>>>>>> On 14-10-2018 15:24, agrays...@gmail.com wrote: >>>>>>>>>> > In a two state system, such as a qubit, what forces the >>>>>>>>>> interpretation >>>>>>>>>> > that the system is in both states simultaneously before >>>>>>>>>> measurement, >>>>>>>>>> > versus the interpretation that we just don't what state it's in >>>>>>>>>> before >>>>>>>>>> > measurement? Is the latter interpretation equivalent to >>>>>>>>>> Einstein >>>>>>>>>> > Realism? And if so, is this the interpretation allegedly >>>>>>>>>> falsified by >>>>>>>>>> > Bell experiments? AG >>>>>>>>>> >>>>>>>>>> It is indeed inconsistent with QM itself as Bell has shown. >>>>>>>>>> Experiments >>>>>>>>>> have later demonstrated that the Bell inequalities are violated >>>>>>>>>> in >>>>>>>>>> precisely the way predicted by QM. This then rules out local >>>>>>>>>> hidden >>>>>>>>>> variables, therefore the information about the outcome of a >>>>>>>>>> measurement >>>>>>>>>> is not already present locally in the environment. >>>>>>>>>> >>>>>>>>>> Saibal >>>>>>>>>> >>>>>>>>> >>>>>>>>> What puzzles me is this; why would the Founders assume that a >>>>>>>>> system in a superposition is in all component states simultaneously >>>>>>>>> -- >>>>>>>>> contradicting the intuitive appeal of Einstein realism -- when that >>>>>>>>> assumption is not used in calculating probabilities (since the >>>>>>>>> component >>>>>>>>> states are orthogonal)? AG >>>>>>>>> >>>>>>>> >>>>>>>> I think because of interference. Consider the paradigmatic double >>>>>>>> slit, with the single electron going through it. It sure looks like >>>>>>>> the >>>>>>>> electron was in two place at once, doesn't it? >>>>>>>> >>>>>>> >>>>>>> *Yes, that's my assessment how the erroneous interpretation took >>>>>>> hold, but only if you restrict yourself to the particle interpretation. >>>>>>> If >>>>>>> the electron travels as a wave, it can go through both slits >>>>>>> simultaneously >>>>>>> and interfere with itself. This is my preferred interpretation; the >>>>>>> only >>>>>>> one that makes sense. AG* >>>>>>> >>>>>>> I'm not sure what you mean by "that assumption is not used in >>>>>>>> calculating probabilities". >>>>>>>> >>>>>>> >>>>>>> *If the operator whose eigenvalues are being measured has a well >>>>>>> defined mathematical form -- e.g., not like |alive> -- it has specific >>>>>>> eigenvectors and eigenvalues, and the state function can be written as >>>>>>> superposition of these eigenvectors. It can be shown that eigenvectors >>>>>>> with >>>>>>> distinct eigenvalues are orthogonal, meaning the Kronecker delta >>>>>>> applies to >>>>>>> their mutual inner products. Therefore, to calculate the probability of >>>>>>> observing a particular eigenvalue, one must take the inner product of >>>>>>> the >>>>>>> wf with the eigenvector which has that eigenvalue. Due to the >>>>>>> orthogonality, all terms drop out except for the term in the >>>>>>> superposition >>>>>>> which contains the eigenvector whose eigenvalue you want to measure. As >>>>>>> you >>>>>>> should see, there is nothing in this process of calculating >>>>>>> probabilities >>>>>>> that in any way implies, assumes, or uses, the concept that the system >>>>>>> is >>>>>>> simultaneously in ALL component states of the superposition (written as >>>>>>> a >>>>>>> sum of eigenvectors). AG* >>>>>>> >>>>>>> >>>>>>>> If you take a sum-over-histories approach it's explicitly assumed >>>>>>>> the electron went via all possible paths. >>>>>>>> >>>>>>> >>>>>>> *I don't know that method, but offhand POSSIBLE PATHS might have >>>>>>> nothing to do with, and possibly independent of SUPERPOSITIONS OF >>>>>>> STATE. AG* >>>>>>> >>>>>>> I don't see what the orthogonality of the basis vectors (and hence >>>>>>>> component states) has to do with the question of interpretation of >>>>>>>> superposition. >>>>>>>> >>>>>>> >>>>>>> *Explained in detail above. AG* >>>>>>> >>>>>>> Clearly the system will be measured in only one state, and this is >>>>>>>> what the orthogonal vectors represent. However the quantum state >>>>>>>> itself >>>>>>>> typically spans more than one dimension of the vector space - that's >>>>>>>> what a >>>>>>>> superposition is. However I think when physicists say that the >>>>>>>> superposition is in all states simultaneously, it's only in a manner >>>>>>>> of >>>>>>>> speaking - a way of conveying the mathematical situation in natural >>>>>>>> language that is inherently classical. >>>>>>>> >>>>>>> >>>>>>> >>>>>>> *It's a totally misleading way to discuss the quantum >>>>>>> superpositions. Even classically, say for the vector space of "little >>>>>>> pointy things" in a plane, each vector can be expressed in uncountably >>>>>>> many >>>>>>> bases, both orthogonal and non-orthogonal. So to claim that one basis >>>>>>> is >>>>>>> somehow preferred, and the vector being expressed as a sum or >>>>>>> superposition >>>>>>> in that basis, is simultaneously in all components of that particular >>>>>>> basis, make no sense whatsoever. AG* >>>>>>> >>>>>>> Reading Born's exchange of letters with Einstein (I'm proud to say >>>>>>>> Born was my great grandfather), it's clear that Born had a conception >>>>>>>> of QM >>>>>>>> that was still very realistic in the Einstein sense. Though they >>>>>>>> disagreed >>>>>>>> significantly and somewhat heatedly, Born still seems to have regarded >>>>>>>> QM >>>>>>>> probabilities as classical probabilities in disguise. >>>>>>>> >>>>>>> >>>>>>> *Einstein realism seems to have been falsified due to Bell >>>>>>> experiments. If that's the case, it would mean that BEFORE measurement >>>>>>> of a >>>>>>> quantum system, it is not only NOT in all states of a superposition >>>>>>> simultaneously for the reasons I have argued (nothing to do with Bell), >>>>>>> but >>>>>>> ALSO has no local preexisting value. AG* >>>>>>> >>>>>>> I don't think he would ever have endorsed the notion that a particle >>>>>>>> is truly in all of the states of the superposition simultaneously. >>>>>>>> >>>>>>> >>>>>>> *Thanks for your input. AG * >>>>>>> >>>>>> >>>>>> >>>>>> >>>>>> The (complex-number-weighted) "path"s of the path integral >>>>>> (sum-over-histories) formulation are all that are needed to define >>>>>> superpositions. >>>>>> >>>>> >>>>> *Can you flesh that out? How can complex numbers be weighted and >>>>> result in superpositions? AG* >>>>> >>>>> "Einstein realism" is restored if *retrocausality* (the path futures >>>>>> can *stochastically* influence the path pasts) is allowed. >>>>>> >>>>> >>>>> *I don't believe it. I think it has hugely absurd implications. AG * >>>>> >>>>>> >>>>>> - pt >>>>>> >>>>>> >>>> The paths (histories) in a path integral (sum over histories) >>>> formulation have complex numbers assigned to them. (That's their >>>> "weights".) >>>> >>>> >>>> http://muchomas.lassp.cornell.edu/8.04/Lecs/lec_FeynmanDiagrams/node3.html >>>> >>>> The Feynman formulation of Quantum Mechanics builds three central ideas >>>> from the de Broglie hypothesis into the computation of quantum amplitudes: >>>> the probabilistic aspect of nature, superposition, and the classical >>>> limit. >>>> This is done by making the following three three postulates: >>>> >>>> >>>> 1. *Events in nature are probabilistic with predictable >>>> probabilities P.* >>>> 2. *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 [image: tex2html_wrap_inline1605] associated with every >>>> history >>>> leading to the event.* >>>> 3. *The quantum amplitude associated with a given history [image: >>>> tex2html_wrap_inline1605] is the product of the amplitudes [image: >>>> tex2html_wrap_inline1609] associated with each fundamental process in >>>> the >>>> history.* >>>> >>>> ... >>>> >>>> Postulate (2) 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. We now have an explicit >>>> formulation for calculating the probabilities for events in terms of the >>>> [image: >>>> tex2html_wrap_inline1605] , quantum amplitudes for individual >>>> histories, which the third postulate will now specify. >>>> ... >>>> >>>> - pt >>>> >>> >>> *Thanks for that. I have a few basic questions about Feynman's >>> path-integral formulation of QM. Firstly, IIUC, Bruce wrote that Feynman >>> initially believed in a particle-only formulation of QM. but later realized >>> this was not possible. Is this true or false? Personally, as I wrote above, >>> I don't see how a particle-only theory of slit experiments makes any sense. >>> Only using a wave model can we imagine that the "particle" goes through >>> both slits simultaneously to produce interference. Secondly, in his >>> particle only, or path integral formulation, how does he choose which paths >>> to use, given that there exists an uncountable number of direct paths, and >>> an uncountable number of paths which loop, go backward, then forward, and >>> so on. How does he choose which paths to use? Thirdly, how does he define a >>> "fundamental process", which is required to define a "history"? TIA, AG* >>> >> >> >> This has been written about by the late Victor J. Stenger, Huw Price, Ken >> Wharton, ... and me, of course. >> >> All are some sort of reification of Feynman paths. >> >> There is the zig-zag particle that goes back and forth in time >> ("eventually"going through both slits). There is the reflective path >> integral (paths in one time direction mirrored with paths going in the >> opposite time direction), etc. >> >> - pt >> > > *Seems like a desperate grasping at straws. How does Feynman choose which > paths to use, or are all equally required for the theory to make correct > predictions? AG* >

My theory, it's a sort of Darwinian struggle: *In this sum-over-histories-and-futures interpretation, “decoherence” is defined as all histories/futures but one die. (In a Darwinian”survival-of-the-fittest analogy, selection is made from a “fitness” probability distribution.)* - https://codicalist.wordpress.com/2018/03/16/mirror-mirror/ - cf. https://codicalist.wordpress.com/2018/09/25/retrosignaling-in-the-quantum-substrate/ This may be a sort of version of quantum Darwinism [ https://en.wikipedia.org/wiki/Quantum_Darwinism ]. - pt -- 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 everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.