On Thursday, August 16, 2018 at 10:05:31 AM UTC, Bruno Marchal wrote: > > > On 15 Aug 2018, at 13:33, Bruce Kellett <[email protected] > <javascript:>> wrote: > > From: Bruno Marchal <[email protected] <javascript:>> > > On 15 Aug 2018, at 01:48, Bruce Kellett <[email protected] > <javascript:>> wrote: > > From: Bruno Marchal <[email protected] <javascript:>> > > On 14 Aug 2018, at 04:30, Bruce Kellett <[email protected] > <javascript:>> wrote: > > 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. > > > I was trying to make sense of the suggestion of many Alices and Bobs > before any measurement. That can easily be implemented by having Alice > select her measurement angle according to the time of some radioactive > decay. Since an infinity of decay times is possible, we get a superposition > of an infinite number of copies of Alice. > > > OK. But we have this in our context too. > > But this makes not difference to the basic argument -- one just picks out > a typical Alice. > > > How? > > > Do you really no know how to pick out a typical component from an ensemble? > > > > I cannot when the elements cannot be distinguished. Alice cannot do that, > but each Bob and Alice picks their counterparts by doing their > measurements, but that take some times. > > > > > You are wrong when you claim that an infinity of couples are required to > make sense of measurements made at arbitrary angles. > > > Why? > > > Because that is not how angular momentum operators in quantum mechanics > work. > > The singlet state is rotationally symmetric, > > > That’s why. > > > That's why what? > > > > That is why a singlet state describe a collection of situations > withAlice’s particles spin well defined in all directions (and the opposite > for Bob). But none know which one. > > > > and can be expressed in any base. But this does not mean that there > actually exists a copy of the observer for each of the potential bases. > That idea makes no sense at all; it is not part of quantum mechanics in any > possible formulation. > > > ? > > That would contradict the complementary principle. A well localised > particle is a particle having almost all possible momenta in many different > histories. > > > For fuck's sake, Bruno. Do you understand nothing of elementary quantum > mechanics? > > > No comment. > > > > > The angular momentum operators do not commute, sure, so that if one has a > precise measurement in one direction, one has no knowledge of the > projection in an orthogonal direction. But the possible values of any such > operator on the spin-1/2 state are +1 or -1 (in units of hbar/2). So there > is no infinity as there is in the case of the complementarity of position > and momentum operators! > > > No problem with this, but Alice can choose to measure that spin in any > direction. > > > > > Besides, it is possible to have exact values for both the total angular > momentum operator (L^2) and any particular component, say L_z if we are > measuring in that direction, and that is all we require here. See the > Wikipedia article: > > > https://en.wikipedia.org/wiki/Angular_momentum_operator#Uncertainty_principle > > > The singlet state does not single out one base, despite the notation. It > describes an infinite of Alice and Bob right at the start. > > > Sure, the singlet state does not single out one base. But that does not > mean that it describes an infinity of observers. Just because you can > measure at any angle does not mean that there is actually an infinity of > observers making all those possible measurements. That notion is just crazy. > > > ? > > It is just what the wave described literally. > > > No, it is not. Look up some reference on the application of the > uncertainty principle to angular momentum operators. (Such as the Wikipedia > article above.) > > > I do not see any problem between what I said and that wiki pages, which is > rather neutral on the interpretations. They do not provide the > “many-worlds” view on this, and some links there suggests they use the > Copenhagen formulation. > > You seem to reintroduce implicitly some collapse in the picture. That’s my > feeling, as this is not clear. When measuring a spin: there are two > possible values *for all possible direction of the spin*. That makes > infinitely many worlds. Same for an electronic orbital. There are as many > world that the possible position of the electron in the orbitals. >
*In such scenario, you'd have to include all bound electrons in the universe, bound to atoms and molecules, from which the number of possible worlds and Alice's would hugely metastasize. I am fine with this scenario provided you add immaculate conception to the multiple universes and Alice's. AG * > Are you OK with this? I try to figure out what is your interpretation of > the SWE. > > 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] <javascript:>. > To post to this group, send email to [email protected] > <javascript:>. > 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.
