On Sat, Oct 5, 2019 at 7:15 PM Bruno Marchal <[email protected]> wrote:
> On 5 Oct 2019, at 07:14, Bruce Kellett <[email protected]> wrote: > > > On Sat, Oct 5, 2019 at 1:10 AM Bruno Marchal <[email protected]> wrote: > >> On 3 Oct 2019, at 13:31, Bruce Kellett <[email protected]> wrote: >> >> And there is no FTL action -- that would be a local hidden variable >> causal explanation, and Bell rules that out. >> >> >> This I do not understand, unless you bring t’Hooft super-determinism. In >> a unique universe, the violation of BI requires that when Alice do a >> measurement she influences and change the “map of the accessible reality” >> of Bob. They still cannot do signalling, but, with or without hidden >> variables, Alice does restrict instantaneously the state available Bob. >> Withe MW, as long as the light has not entangle Bob, Bob can make a >> measurement entangling him so other Alice of the multiverse. Everyone will >> agree with what the singlet state predicts, and no FTL signalling, nor >> influence has to occur. >> > > You contradict yourself, Bruno. You say "when Alice do a measurement she > influences and changes the 'map of accessible reality' of Bob”. > > > Yes, of course, but that influence propagate at a speed slower than light, > but successive entanglement “contagion”. > > Then you say "Everyone will agree...no influence has to occur.” > > > You confuse the Bobs to whom Alice can access, to the all Bobs, including > those Alice will never been able to access. > Your twisting does not get you out of the fact that you have contradicted yourself. > I think your complete failure to understand the non-local entangled state > > > (Semantic play) > You agreed that you did not understand the non-local entangled state. > -- the fact that the wave function itself is non-local -- is at the root > of all your misunderstandings, and leads you into these contradictory > positions. > > > No, you are not understanding what I said. Reread the post and the full > explanation. > There is no full explanation in any previous post of yours. > Let us start again. Consider the entangled singlet state that we have been > talking about: > > |psi> = (|+>|-> - |->|+>)/sqrt(2). > > This refers to two spacetime locations; > > > You can’t at the start impose your own interpretation. You know that I > disagree with this interpretation since the start. > For goodness sake, Bruno, what are you talking about? You cannot 'disagree with this interpretation'. That is what the singlet state when the particles have separated means. The singlet state refer to a continuum of relative worlds accessible to all > Alice and Bobs sharing the entangled particles. > Ah, yes. Here we go again. Your really are confused by this state, Bruno. You keep referring to the fact that it is rotationally invariant, and can be analysed in any basis, as though that made a substantive difference. The results obtain in any basis, true. But that is a trivial observation of symmetry. It does not explain the observed experimental results. > let us call them (t1,x1) and (t2,x2), where the x1 and x2 stand for > 3-vectors. The spacetime interval between these particles or events when > measured, is s^2 = (t1-t2)^2 - (x1-x2)^2. When s^2 > 0, the separation is > time-like, and when s^2 < 0, the separation is space-like (in the (+,-,-,-) > metric that I am using. When Alice makes her measurement, she gets, say, > 'up’. > > > Now, all Alice get some result, some get ‘down' to. > Read on, old son. You might find that this is mentioned below. > According to the above non-separable wave function, that means that Bob > gets only the ket |->, > > > That is vague. It means that Alice will access to the Bobs who get that > state, and never access to the Bobs who did not got it. > Exactly. And this is what you are required to explain. Just stating it as a fact is not an explanation. in the basis of Alice's measurement. Similarly if Alice gets 'down', Bob > must measure the |+> ket, in Alice's basis. By rotating these kets into his > local measurement basis, Bob gets 'up' or 'down' with the required > probabilities. > > … relatively to their corresponding Alices, only. > Oh dear...... > This is a what your statement "when Alice do a measurement she influences > and changes the 'map of accessible reality' of Bob" means. And I agree with > this. > > > I am not sure, because that influence never get higher than the speed of > light. > Who said that it did? Read on and stop interrupting. > Bob could find a non correlated state, and that will mean that such Bob > and Alice are in different worlds, and will never meet. The state just > describes their possible relative states. > The state describes the observed results. There are no "other worlds" in which there are no correlated results. > So (this all assumes, without loss of generality, a frame in which Alice's > measurement is first) Alice's measurement does inevitably affect the state > that Bob can measure. > > > Which Bob? She does not affect Bob’s state “physically”, she just learn > that she is in a universe in which she can access only to the Bob who will > find the correlated state, and never access to the Bob who get different > states. No FTL influence. > No, no FTL influence. Read on. You haven't said anything of value yet. If there is only one Alice and Bob, then there would be FTL influences. > No. You can't get away from this idea, can you. Try and clear your mind of its prejudices and think what non-local might mean. I am attempting to explain it to you in words of one syllable. The question then is, how does this effect come about? What is the > mechanism? You appear to be only able to think of some FTL influence. > > > No. You are the one inking this. > You really are the limit, Bruno. You ascribe your own short-sightedness to everyone else. Clear your mind of these prejudices, Bruno, and listen to what I am saying. > With the MW, at no moment Alice change the state of Bob. She just change > her own map of histories available. She knows that she can no more met a > Bob with another state than the correlated one. > How does she know this? What is the magic? > That is why I take Aspect experience as an evidence of the other worlds, > as I do not give any sense to any FTL influence. > > But that cannot work. There are a lot of problems with such an idea. Apart > from violations of special relativity, it would involve the exchange of > some particle or tachyon that conveys Alice's result and polarizer > orientation to Bob *before* he makes his measurement. Dynamics for that > might be conceivable, but there is a problem in deciding whether it is a > particle or an FTL tachyon that must be exchanged. Notice that when this > information has to be sent out from Alice's measurement, Bob still has not > made his measurement, and there is no way at the spacetime point (t1,x1) to > know when Bob will make his measurement. It could be at either space-like > or time-like separation, s^2 > 0 or s^2 < 0, and there is no way of > knowing, so there can be no suitable dynamics that will send a particle or > a tachyon appropriate to the situation (because the situation is unknown at > the relevant time). > > > I agree. No FTL, but if the collapse exist and is a physical phenomenon, > that violation of Bell’s inequality make non-locality into FTL influence. > That is why I reject the uniqueness of Bob and Alice. > The uniqueness or otherwise of Bob and Alice makes no difference. By multiplying them you have not actually achieved anything. > There is an additional dynamical problem in understanding how this > particle or tachyon conveying Alice's information is actually going to > affect Bob's state when it arrives there. If the correct statistics are to > come out at the end, it would seem that this intermediate particle must > suppress that part of Bob's state that is inconsistent with Alice's result. > I leave the design of such dynamics to you -- it is beyond me to even > begin to imagine it. On top of this, there is the problem that in some > other frame, Bob's measurement is first, so his measurement must affect the > joint state in a symmetrical way!!!!! > > I think this goes beyond impossibility to the point of absurdity. > > That is my point, exactly. > I am glad we can agree that FTL exchanges are out of the question. > So what are we left with? I think we can rule out FTL interaction, or even > sub-light speed interactions for time-like separations, because there are > too many contradictory requirements on such a particle exchange of > information. But the influence must occur, because the final correlations > can only be explained in that way. (Attempts to explain the correlations > away by MWI, or further interactions when the light cones overlap, have all > failed. > > Nope. You have not shown this. > Well, I have looked at your "explanations", and at a lot of other MWI so-called explanations, and not one of them has been satisfactory. These "explanations" are either hopelessly vague, or they misunderstand what is required, or, like Wallace, they simply wimp out of any explanation at all. If you can do better, then do it. But despite years of asking, you still have not come up with any credible explanation. Mainly because there are no relevant interactions at the point of overlap > of the future light cones from the separated measurements.) > > We are left with a non-local influence, or interaction. Where by > non-local, I mean precisely that -- an action on two separated spacetime > points *without* there being any local causal contact between them, by > exchange of particles or tachyons or whatever. If there were such an > exchange, impossible as it seems, that would be a *local* explanation, > because interactions via particle exchanges are the paradigm of locality. > > I know that this is contrary to all our instincts -- we believe that there > is no "spooky action at a distance". And I know that your rejection of such > action at a distance is why you have always called references to > 'non-local' effects, FTL exchanges. > > > I say explicitly the contrary!!!!!! > Let's at least be honest about this, Bruno. You are always calling non-locality, FTL action. > I reject FTL, and do no need them, thanks to the MWI. You should reread > cautiously my post, as you attribute me the very idea that I reject. > I am not ascribing belief in FTL action to you. Again, I ask you not to misrepresent what I say. But you have not shown that MWI removes non-locality. I hope it is clear that I absolutely reject that interpretation, and do not > think that any dynamical theory of such FTL exchanges could ever be made to > work. > > Non-locality is exactly what it says -- a non-local influence or > interaction between two points separated in space and time, whether by a > space-like or a time-like interval -- call it "spooky action at a distance" > if you must. But there is nothing spooky about it --no other rational > explanation of the situation is available. > > > So, you are the one introducing the spooky action, and indeed, if there is > only one couple Alice-Boob, that is the only solution, but with the MWI, we > don’t need them at all, as I have explained, but seems to have > misunderstood my post. > I have read all your posts carefully, and have not misunderstood anything. The trouble is that you have never explained how MWI removes non-local influence. You always defer to some magical "matching of worlds" or some such. That is not an explanation. > Your further point about an infinity of different possible 'worlds' for > Alice and Bob coming from the rotational invariance of the singlet state is > just a smoke screen, having nothing to do with any rational explanation of > what is going on. > > > … that confirms you have fail to understand my point, as this is crucial > in exposing why the violation of BI implies only the necessity of many > worlds or many histories to avoid FTL influence. > OK. I have failed to understand. Maybe that is because you have failed to explain how this works. > Please reread my explanation in my previous post, as it seems to me that > you have missed it. > It is beginning to sound like this magical post in the past that John Clark keeps referring to -- the post where you actually explain everything. The trouble is that we cannot find any such post. Bruce -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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