> On 9 Jul 2018, at 02:37, Bruce Kellett <[email protected]> wrote: > > From: Bruno Marchal <[email protected] <mailto:[email protected]>> >>> On 6 Jul 2018, at 20:52, Brent Meeker <[email protected] >>> <mailto:[email protected]>> wrote: >>> >>> >>> On 7/6/2018 9:26 AM, Bruno Marchal wrote: >>>> It is like they find themselves in the relevant partition of the >>>> mutilverse, but as there has not been any collapse, nothing has needed to >>>> propagate after than light. The non-locality, or better inseparability, >>>> just assures that whatever differentiation will occur locally, they will >>>> have the correlated spin, but at no point are we assured that Alice meet >>>> something like the original Bob. The differentiation of the universe >>>> develops locally. >>> >>> No, it differentiates in a coordinated, space-like way, keeping that Alice >>> with that Bob so that only the correctly correlated Alice and Bob can meet, >>> i.e. be in the same world at the same time and place. >> >> ? >> >> That my point. But that is why we don’t need FTL influence. In the >> multiverse, they remains the same, but the inequality of Bells assured them >> of not knowing in which branch they are. > > Brent's comment is a misleading way to put it. There are no multiple copies > of Alice and Bob that do not have the correct correlations and have to be > eliminated.
Before they measure their spin, that does not make sense. You keep using an identity thesis which just don’t make sense, neither in Everett-QM, nor with Mechanism (on which Everett-QM relies). > Every Alice copy meets every Bob copy, and they all have the correct > correlations. OK. > It is explaining how this happens that is the whole point of the exercise. > This can only happen if the probability that any Bob copy gets 'up' when > Alice gets 'up', or the probabilities of any of the other three possible > combinations, are all correct. Getting these probabilities correct requires > non-local knowledge of the relative polarizer angles. If you don't understand > this, then you have not understood the basic quantum mechanics. If “non-local” means FTL, I disagree. Only Non-local + definite unique outcome implies FTL. That is what the violation of Bell’s inequality shows. But with Everett, we keep the non-locality, but without any FTL. I have followed some years ago a very nice talk by Bob Cooke (a quantum physicist) using category theory to explicitly show that in EPR and teleportation, the flux of information is local. No action at a distance, as long as no physical collapse occurs. Yu might find the slide of the conference by googling on "Bob Cooke teleportation”. > > >>>> Once Alice and Bob are space-light separated, they will never meet again >>>> after they made local measurement. >>> >>> But they do meet again. Only events are space-like separated. People have >>> persistent world-lines which are both space-like and time-like depending >>> on the events chosen. But "meeting", being at the same events, is >>> invariant. >>> >>>> Each will meet only the corresponding (correlated) person, but there is no >>>> reason we can identify them in any single word. >>> >>> You can identify whomever meets as being in a single world. That's the >>> point of Bruce's exposition. >> >> I am not sure I see your or Bruce point. I am not sure which Alice and Bob >> you are talking about, nor if what you say would entail any FTL in a single >> world. Entanglement just correlate infinities of Alice with infinities of >> Bob. There is no notion of one Bob, once Alice and Bob are separated by a >> sufficiently great distance. > > There are no infinities of Alice or Bob. There are no such infinities in > quantum mechanics, or in the Schrödinger equation. Just an atom of hydrogen implies this infinity in the position base. The “electronic” cloud is the map of all the worlds you are in and will access to if you measure the position of the electron. It might be finite in some “loop-gravity”like theory, but with the “classical” SWE, even just one particles diffuse in different place in infinitely many histories. > Once you set a base, there are only two copies of each experimenter. FAPP, but that is going on the slope of abusing of the identity thesis. > And the base is set by choosing what to measure. Once that choice is made, > the other possible bases drop out of consideration. OK. > When Alice and Bob meet, they are in the one world, even if there are four > possible such meetings. You then follow back according to the sequences of > observations recorded in their lab books -- this is exactly like the W/M > duplication experiment. So you follow back a particular world line -- there > is no ambiguity. > > >> May be you could elaborate. You believe that physical single world - FTL >> influence exist? I think you will need more than a violation of Bell inquiry >> for this. > > There is no FTL signalling, and that is all that is required for Lorentz > invariance. Adding extra requirements is your fantasy, not physics. We both agree that there is FTL signalling. What I say is that there is no FTL influence at all, in EPR, when developed in the Everett theory. I don’t see it. When they are space-separated, given they don’t know in which branch they are, they can find result which would violate Bell’s inequality, but this means that they will never met. Each Alice and Bob will only met those correlated to them. All interactions are local. No mysterious magic forcing the result of Bob or Alice to influence the outcome of the others. We need to take into account the many numbers of Alice (Bob), because none knows in which branch they are. They know only that they are correlated, and that means only that when they come back they will observe those correlations, but as there has not been any collapse, that is explained entirely by local interactions, as they were in the right branch at the start, due to the preparation of the singlet state. 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] > <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]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
