On Sunday, April 22, 2018 at 5:22:48 PM UTC, [email protected] wrote: > > > > On Sunday, April 22, 2018 at 4:19:44 PM UTC, Bruno Marchal wrote: >> >> >> On 20 Apr 2018, at 03:18, Bruce Kellett <[email protected]> wrote: >> >> From: Bruno Marchal <[email protected]> >> >> On 18 Apr 2018, at 15:45, Bruce Kellett <[email protected]> wrote: >> >> From: Bruno Marchal <[email protected]> >> >> On 17 Apr 2018, at 13:52, Bruce Kellett <[email protected]> wrote >> >> >> But note particularly that the spin measurement is made in the basis >> chosen by the experimenter (by orienting his/her magnet). >> >> >> OK. >> >> The outcome of the measurement is + or -, >> >> >> For Alice and Bob, OK. >> >> not one of the possible infinite set of possible basis vector >> orientations. The orientation is not measured, it is chose by the >> experimenter. So that is one potential source of an infinite set of worlds >> eliminated right away. The singlet is a superposition of two states, + and >> -: it is not a superposition of possible basis vectors. >> >> >> ? (That is far too ambiguous). >> >> >> ????? It is not in the least ambiguous. The singlet state is not a >> superposition of basis vectors. >> >> >> ? >> >> The singlet state is the superposition of Iup>IMinus> and (Minus>Iup>. >> >> >> Those are not generalized basis vectors: they are eigenfunctions of the >> spin projection operator in a particular basis. The singlet state is not a >> superposition of vectors from different bases. >> >> >> Did I say that? >> >> >> >> If you think about it for a little, the formalism of QM does not allow >> the state to be written in any way that could suggest that. >> >> I don't know what Everett says in his long text, but if it is any >> different from the above, then it is not standard quantum mechanics. >> Deutsch is a different case. He has a very strange notion about what >> constitutes different worlds in QM. Standard QM and Everett's >> interpretation are very clear: different worlds arise by the process of >> decoherence which diagonalizes the density matrix. The net effect is that >> worlds are, by definition, non interacting (contra Deutsch's ideas). >> >> >> ? >> >> >> This relates to your lack of comprehension above. >> >> >> >> Patronising !!!!!!! >> >> >> Merely pointing out your apparent lack of comprehension when you fail to >> appreciate the difference between the eigenvectors of a particular operator >> and the free choice of a basis for Hilbert space. >> >> >> You aggravante your case. >> >> >> >> Deutsch has two distinct notions of "world" in his approach. He has the >> standard Everettian notion of a "relative state" corresponding to each term >> in the superposition of possible measurement outcomes. These relative >> states are made definite by decoherence, >> >> >> Relatively. Decoherence is only entanglement (with NON-collapse). >> >> >> So what? >> >> and then correspond to different, effectively orthogonal, worlds, each of >> which represents the experimenter observing one particular result. But >> Deutsch also has the idea that the infinity of possible bases for an >> unpolarized qubit also represents an infinity of worlds. >> >> >> That is necessary, and Everett explains this well when he shows that the >> choice of the base to describe the universal wave is irrelevant. >> >> >> Sure, the choice of basis is irrelevant. It is just that some bases are >> more useful than others. And there is no use at all in trying to use all >> bases at once! >> >> (A bit like the choice of the universal Turing formalism is irrelevant to >> get the theology and the physics). >> >> >> This is quite a different notion, and does not occur in Everettian theory. >> >> >> I disagree with this. >> >> >> Well, you are wrong. >> >> In this second notion of "world", the worlds remain in superposition and >> continue to interfere -- there is no separation into disjoint, >> non-interacting worlds. In fact, it is precisely this continued >> interference of these supposed "worlds" that is the explanation for the >> action of quantum computers -- which Deutsch seems to think actually >> *prove* his notion of quantum "many-worlds". He is out on a limb on this >> one, and few experts, even in the quantum computing field, agree with >> Deutsch on this new notion of "worlds". The essential continued >> interference between the different basis states in fact means that the >> "worlds" remain inextricable "one world". (See some of Scott Aaronson's >> comments on Deutsch and many-worlds in his lecture notes on quantum >> computing.) >> >> So when you continue to refer to an "infinity of worlds" for the >> measurements on the entangled spin states, you are using a notion of >> "world" that does not occur in Everett, and is inherently controversial, if >> not entirely meaningless. >> >> >> I use the “Herbrand” interpretation of quantum mechanics without >> collapse. I mean: it is literal QM (in a sense that logicians have made >> precise) without collapse up to a choice of any arbitrary base. >> I don’t believe in any worlds, to be clear. It always means some reality >> satisfying some formal constraints. >> >> >> I think you believe in a world. How else do you go about your daily life? >> >> >> Like in a dream. Like in any computations which get a high relative >> probability. Of course you can call that worlds, but they have no >> fundamental ontology. But please read my papers, or the old posts. >> >> >> >> Or are you like most mathematicians: believing in platonism at work, but >> believing in nominalism the rest of the time? >> >> >> I am a scientist. I keep my belief for myself except those I put on the >> table as hypotheses, and reason from that. I do that in theology, which is >> not done frequently especially since 1500 years (but some have the right >> spirit, like Spinoza, and many others less well known). >> >> >> >> >> But even if you can manufacture an infinity of universes, you still have >> not shown how this removes the non-locality inherent in the quantum >> formalism. >> >> >> You have not shown non locality. >> >> >> I have demonstrated non-locality in the Everettian context many times. >> The simplest demonstration was in the timelike separation of Alice and >> Bob's measurements. It is in the archives if you don't recall the details. >> The argument then is that any local influence that would explain the >> timelike separated measurements must also work for spacelike separated >> measurements, and that is not possible. >> >> >> At all time there is an infinity of “worlds”. When Alice chose her >> direction, that remains true, and her measurement will tell us if she >> belongs to a world with “spin” down or up, she will automatically know that >> whatever Bob she will meet, will have the corresponding results, no action >> at a distance here. >> >> >> Again, you keep referring to this non-existent infinity of worlds — >> >> >> “worlds” would be better. >> >> a notion that has nothing to do with Everett or his interpretation of >> quantum theory. "... She will automatically know that whatever Bob she will >> meet, will have the corresponding results...". This is precisely the >> question that you have not answered -- how does this happen? >> >> >> Because in ALL “worlds” Alice and Bob have they spin described by the >> no-separable singlet state. The statistics seems non-local, due to their >> ignorance of which partition of the wave function they belong to. >> >> >> No, due to the fact that any any "world" in which they find themselves >> the correlations indicate non-locality. >> >> >> Yes, but not any action at a distance. >> >> >> >> >> What is the particular magic that you put in the mix to ensure that the >> correct correlations emerge? >> >> >> Only QM, without collapse. >> >> >> That is truly magical, and you have no evidence for this whatsoever. >> >> >> It follows from both QM and Comp. If Alice and Bob are space-separated, I >> cannot even makes sense of how you can measure correlations, given that >> once they are separated, whatever result they got, will be shared with >> different Alice and Bob in different branch. >> > > *Bruno, please get a clue. In Bell experiments Alice and Bob are NOT > space-separated. They are in the same laboratory! It's from the correlation > results that action at a space-separated "influences" is INFERRED. It was > Bell's theorem that allowed such experiments to be done, since prior to > that, and presently, and forever, it's IMPOSSIBLE in principle to > space-separate Alice and Bob, and do measurements on both. AG* >
*Correction to above text:* *Bruno, please get a clue. In Bell experiments Alice and Bob are NOT space-separated. They are in the same laboratory! It's from the correlation results that "action" (aka "influences") for space-separated events is INFERRED. It was Bell's theorem that allowed such experiments to be done, since prior to that, presently, and presumably forever, it's IMPOSSIBLE in principle to space-separate Alice and Bob and do measurements on both. AG* > > >> I am not even sure we can define what could be an action at a distance in >> the quantum formalism. >> > > > *It means, for the singlet state, that conservation of spin angular > momentum is conserved for space-separated events. Not saying I believe it, > but that's what it MEANS. AG* > > >> The notion does not even makes sense when we assume special relativity. >> The only reason to believe this is the habit to think that there is only >> one bob and one Alice, >> >> *To believe there are additional Alice's and Bob's is ridiculous on its >> face. Admit it! AG* >> >> > which makes no sense once separated, unless they are correlated with a >> third observer, but then, again by looking at the wave without collapse, >> there will be no action at a distance. The no locality is only an >> appearance due to the fact that we belong to infinities of histories, and >> cannot known which one we are in. >> >> Bruno >> >> >> >> >> Bruce >> >> -- >> 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. >> >> >> -- 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.
