> On 2 Aug 2018, at 01:32, Bruce Kellett <[email protected]> wrote: > > From: Bruno Marchal <[email protected] <mailto:[email protected]>> >>> On 1 Aug 2018, at 06:19, Bruce Kellett <[email protected] >>> <mailto:[email protected]>> wrote: >>> >>> >>> No, there are not any infinities of anything. You simply confuse yourself >>> by continuing to claim such things which are not part of quantum mechanics. >> >> >> The singlet state just means that They will see correlated result when >> coming back together. Let me put it in this way: if Alice and Bob are space >> separated, I do not see how to give meaning to “to be in the same branche”, >> and they might individually get non correlated spin measurement? > > It is easy to see how they can be in the same branch, even if space-like > separated. I gave an account of how all measurements are made in the same > branch by starting with the time when Alice and Bob meet to compare notes > after their series of experiments and working backwards to show that, since > neither can jump between branches, all measurements must have been made in > the same branch. > > You can do the same thing in the forwards time direction by considering that > the singlet is prepared in one world.
I cannot make sense of this. Preparing a singlet state is typically done in an infinity of “worlds” (or some very big numbers of worlds in some version of quantum gravity, but for simplicity I assume just “classical” QM). I have to go. Will read the sequel later. But it seems to me that you constantly postulate a collapse. The notion of singlet state is typically a many-world construction, even in Copenhagen before the "measurement/collapse”. Bruno > The component particles move off in separate directions, but they can't jump > worlds either, so when Bob gets his particle to measure, he is necessarily in > the same world as that in which Alice makes her measurement -- the singlet > state itself guarantees that. Then they make their measurements: each gets > either up or down, so each splits into two branches. But the branch with, > say, Alice_up is connected with the original branch in which Bob sits. He > splits into two branches on measurement, but again, each branch is connected > with the original Alice branches. There are now four branches: > Alice_up-Bob_up, and so on for the other combinations. Each of these branches > defines a single world in which there are a pair of measurements. And, > because of the way in which these branches are always interconnected, the > results of each experimenter, if repeated many times, will always have the > correct quantum correlations. There are no other branches -- and no > unconnected measurements that have, somehow, to be discarded -- they can > never get uncorrelated spin measurements! > > >> Bell’s inequality will not been violated, because that Bob and Alice will >> never meet again. Each of them will meet only their relevant counterparts >> when they will “meet again”. >> >>>> and all what they both know is that they share some historical reality >>>> with a relative partner, so that their simps are correlated, but they are >>>> are ignorant and thus distributed on infinitely many histories, with all >>>> the correlation between different spin “angle” (assuming a fixed base to >>>> describe them). >>>> I might be wrong, but the violation of Bell’s inequality (or >>>> Kochen-Specker theorem) does not entail any physical instantaneous action >>>> at a distance. I have seen may attempt to prove this, but they always >>>> favour a branch in a way or another, forgetting the probabilities bear on >>>> different portioning of the multiverse in the big picture. >>> >>> Any evaluation of a set of correlations between experimental results >>> happens in one branch of the superposition. So much for "favouring a branch >>> in a way or another." There is simply no other way to evaluate the >>> correlations. There is no "big picture" that is going to change this >>> conclusion. >> >> Then you assume some collapse. > > As usual, that is your fantasy (i.e., a meaningless bolt-hole by which to > escape an inevitable mathematical conclusion). No collapse is assumed. > >>>> It makes the whole physics becoming covariant, despite necessary relative >>>> local appearance of what seem to be an action at a distance. There are >>>> none, but to show this, we must take into account the fact that Alice and >>>> Bob find all correlated results in all directions. >>> >>> Physics is covariant in any case. The non-locality is real -- it is not >>> just an 'appearance'. Bell's theorem and the observed correlations prove >>> this. >> >> I don’t see this. The violation of Bell’s inequality is real, but without >> any collapse, all interactions are local, and spread locally fro the place >> where they have been done. That follows from the wave only, and that >> guaranties that Alice and Bob, when coming back, will see the >> correlation/violation, but Alice and Bob does that only with some relative >> counterpart of Bob and counterpart of Alice respectively. > > You keep returning to this idea of a "common cause" explanation. And that, as > we know, is ruled out by Bell's theorem. And all attempts to undermine Bell's > theorem end in disaster -- Bell's theorem is called a theorem for good reason. > >> Like Maudlin says: “Or finally once can both avoid collapses and retain >> locality by embracing the Many-Minds ontology, exacting a high price from >> common sense”. > > That refers directly to the "many-minds" interpretation of QM. And Maudlin, > as well as everyone else, has long since moved on from this position. You > should go to the library and read the third edition of Maudlin's book for his > more recent position. > > 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] > <mailto:[email protected]>. > To post to this group, send email to [email protected] > <mailto:[email protected]>. > Visit this group at https://groups.google.com/group/everything-list > <https://groups.google.com/group/everything-list>. > For more options, visit https://groups.google.com/d/optout > <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]. 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