> On 14 Aug 2018, at 04:30, Bruce Kellett <[email protected]> wrote: > > From: Bruno Marchal <[email protected] <mailto:[email protected]>> >>> On 13 Aug 2018, at 00:48, Bruce Kellett <[email protected] >>> <mailto:[email protected]>> wrote: > >>>> but the FTL are needed only if we associate the mind on Bob and Alice to >>>> the same branche, which has no meaning for me once they are space >>>> separated. >>> >>> You might not accept that they can be in the same branch, but that does not >>> mean that it is not a proven fact. >> >> If they are space separated, I am not sure I can make sense of being in the >> same branch. > > You appear to be referring to the presence of quantum fluctuations > continually splitting the classical Alice and Bob into multiple copies -- the > point that Jason has made.
That points is correct, but I was alluding to the infinity of Bob and Alice couples associated with the singlet state. That is needed to tackle the case where Alice and Bob makes non orthogonal measurements. The singlet state does not single out one base, despite the notation. It describes an infinite of Alice and Bob right at the start. > I think I have answered this in my reply to Jason. Different disjoint > classical worlds arise only if the quantum events are amplified to classical > significance by decoherence forming thermodynamically irreversible records of > the event in the environment. OK. But if QM is true, that is always an approximation. Classicality emerges from the laws of big numbers, like entropy. > This does not happen for the majority of quantum fluctuations that underlie > our classical states. Alice and Bob both have (quasi-)classical identities > that are unaffected by such fluctuations. I agree. I was not using the quantum fluctuations, despite this too multiplies the Alice-Bob couples. But not in a relavant way for our analysis of the singlet state. > Just as the temperature of the air is not affected by random molecular > motions. As in statistical mechanics, these fluctuations are averaged over > and essentially all cancel out. They can be safely ignored (FAPP if you must, > but we are talking practicalities here, not undetectable quantum events.) I am OK with this. > > > >>> Determinism has nothing to do with it. Aspect and Bell rule out >>> deterministic local theories, so non-locality is the only possibility. >>> Many-worlds does not change that. >> >> Determinism is the issue. In a collapse theory, you need indeterminism to >> assure the non signalling FTL of information. But you have still some >> physical FTL/simultaneous action. > > No, you just need randomness. That is necessary in MWI as well. Physical FTL > is not necessary. There is no randomness in the universal quantum wave. Only in the mind of the “splitter” observers. > >> With the MW, the situation is entirely deterministic and there is no need of >> any FTL. > > MWI may be deterministic. But then, the loss of symmetry when Alice measures > the singlet state is also entirely deterministic -- it is part of what > unitary evolution according to the Schrödinger equation gives you. It is not > different with many-worlds. OK. > > >>> Both Bell's theorem and Aspect's results are true in many-worlds as in any >>> other interpretation of QM. >> >> Of course. >> >>> Don't you understand that that is why most commentators from the >>> many-worlds perspective try to show that Bell's theorem does not apply to >>> many worlds? >> >> They are wrong. Bell’s violation is necessary in all branches. But what >> happens is that if one branch is selected, by collapse or by hidden >> variables, then *that* transform the non-locality (Bell’s violation) into >> FTL. > > That is not true. What happens in a typical branch of a superposition is true > for all branches. Like the Bells inequality violation? OK. Like some particular result of measurement? I don’t think so. > And what is true for all branches is necessarily true for the whole. ? That does not follow. Not sure what this could mean. Ovipsly, we cannot test the Bell’s inequality in the entire multiverse, as we cannot travel in between worlds. The whole thing do not violate the Bell’s inequality, as QM is a boolean theory, and with the MW, the big whole is again boolean, but explain why the local perception lead to the quantum reality. > The "one branch" is not selected by collapse or hidden variables, it is > selected as typical for the purposes of calculation -- 'in the mind' as it > were. Yes, but distant observer do not need to select the same branches. > >> Without collapse, we don’t need hidden variables, nor any FTL, to explain >> the non-locality and why it never disappears. > > Many-worlds is non local because it is non-local in every branch. Can't you > see the logic of this? If this means no FTL, not event influence (not just non signalling) then I am OK with this. 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.
