> On 22 Apr 2018, at 19:22, [email protected] wrote: > > > > On Sunday, April 22, 2018 at 4:19:44 PM UTC, Bruno Marchal wrote: > >> On 20 Apr 2018, at 03:18, Bruce Kellett <[email protected] >> <javascript:>> wrote: >> >> From: Bruno Marchal <[email protected] <javascript:>> >>>> On 18 Apr 2018, at 15:45, Bruce Kellett < >>>> <javascript:>[email protected] <javascript:>> wrote: >>>> >>>> From: Bruno Marchal <[email protected] <javascript:>> >>>>>> On 17 Apr 2018, at 13:52, Bruce Kellett < >>>>>> <javascript:>[email protected] <javascript:>> wrote >>>>> >>>>>> But note particularly that the spin measurement is made in the basis >>>>>> chosen by the experimenter (by orienting his/her magnet). >>>>> >>>>> OK. >>>>> >>>>>> The outcome of the measurement is + or -, >>>>> >>>>> For Alice and Bob, OK. >>>>> >>>>>> not one of the possible infinite set of possible basis vector >>>>>> orientations. The orientation is not measured, it is chose by the >>>>>> experimenter. So that is one potential source of an infinite set of >>>>>> worlds eliminated right away. The singlet is a >>>>>> superposition of two states, + and -: it is not a >>>>>> superposition of possible basis vectors. >>>>> >>>>> ? (That is far too ambiguous). >>>> >>>> ????? It is not in the least ambiguous. The singlet state is not a >>>> superposition of basis vectors. >>> >>> ? >>> >>> The singlet state is the superposition of Iup>IMinus> and (Minus>Iup>. >> >> Those are not generalized basis vectors: they are eigenfunctions of the spin >> projection operator in a particular basis. The singlet state is not a >> superposition of vectors from different bases. > > Did I say that? > >> >> >>>>>> If you think about it for a little, the formalism of QM does not allow >>>>>> the state to be written in any way that could suggest that. >>>>>> >>>>>> I don't know what Everett says in his long text, but if it is any >>>>>> different from the above, then it is not standard quantum mechanics. >>>>>> Deutsch is a different case. He has a very strange notion about what >>>>>> constitutes different worlds in QM. Standard QM and Everett's >>>>>> interpretation are very clear: different worlds arise by the process of >>>>>> decoherence which diagonalizes the density matrix. The net effect is >>>>>> that worlds are, by definition, non interacting (contra Deutsch's ideas). >>>>> >>>>> ? >>>> >>>> This relates to your lack of comprehension above. >>> >>> >>> Patronising !!!!!!! >> >> Merely pointing out your apparent lack of comprehension when you fail to >> appreciate the difference between the eigenvectors of a particular operator >> and the free choice of a basis for Hilbert space. > > You aggravante your case. > > >> >>>> Deutsch has two distinct notions of "world" in his approach. He has the >>>> standard Everettian notion of a "relative state" corresponding to each >>>> term in the superposition of possible measurement outcomes. These relative >>>> states are made definite by decoherence, >>> >>> Relatively. Decoherence is only entanglement (with NON-collapse). >> >> So what? >> >>>> and then correspond to different, effectively orthogonal, worlds, each of >>>> which represents the experimenter observing one particular result. But >>>> Deutsch also has the idea that the infinity of possible bases for an >>>> unpolarized qubit also represents an infinity of worlds. >>> >>> That is necessary, and Everett explains this well when he shows that the >>> choice of the base to describe the universal wave is irrelevant. >> >> Sure, the choice of basis is irrelevant. It is just that some bases are more >> useful than others. And there is no use at all in trying to use all bases at >> once! >> >>> (A bit like the choice of the universal Turing formalism is irrelevant to >>> get the theology and the physics). >>> >>> >>>> This is quite a different notion, and does not occur in Everettian theory. >>> >>> I disagree with this. >> >> Well, you are wrong. >> >>>> In this second notion of "world", the worlds remain in superposition and >>>> continue to interfere -- there is no separation into disjoint, >>>> non-interacting worlds. In fact, it is precisely this continued >>>> interference of these supposed "worlds" that is the explanation for the >>>> action of quantum computers -- which Deutsch seems to think actually >>>> *prove* his notion of quantum "many-worlds". He is out on a limb on this >>>> one, and few experts, even in the quantum computing field, agree with >>>> Deutsch on this new notion of "worlds". The essential continued >>>> interference between the different basis states in fact means that the >>>> "worlds" remain inextricable "one world". (See some of Scott Aaronson's >>>> comments on Deutsch and many-worlds in his lecture notes on quantum >>>> computing.) >>>> >>>> So when you continue to refer to an "infinity of worlds" for the >>>> measurements on the entangled spin states, you are using a notion of >>>> "world" that does not occur in Everett, and is inherently controversial, >>>> if not entirely meaningless. >>> >>> I use the “Herbrand” interpretation of quantum mechanics without collapse. >>> I mean: it is literal QM (in a sense that logicians have made precise) >>> without collapse up to a choice of any arbitrary base. >>> I don’t believe in any worlds, to be clear. It always means some reality >>> satisfying some formal constraints. >> >> I think you believe in a world. How else do you go about your daily life? > > Like in a dream. Like in any computations which get a high relative > probability. Of course you can call that worlds, but they have no fundamental > ontology. But please read my papers, or the old posts. > > > >> Or are you like most mathematicians: believing in platonism at work, but >> believing in nominalism the rest of the time? > > I am a scientist. I keep my belief for myself except those I put on the table > as hypotheses, and reason from that. I do that in theology, which is not done > frequently especially since 1500 years (but some have the right spirit, like > Spinoza, and many others less well known). > > > >> >>>>>>>> But even if you can manufacture an infinity of universes, you still >>>>>>>> have not shown how this removes the non-locality inherent in the >>>>>>>> quantum formalism. >>>>>>> >>>>>>> You have not shown non locality. >>>>>> >>>>>> I have demonstrated non-locality in the Everettian context many times. >>>>>> The simplest demonstration was in the timelike separation of Alice and >>>>>> Bob's measurements. It is in the archives if you don't recall the >>>>>> details. The argument then is that any local influence that would >>>>>> explain the timelike separated measurements must also work for spacelike >>>>>> separated measurements, and that is not possible. >>>>> >>>>> At all time there is an infinity of “worlds”. When Alice chose her >>>>> direction, that remains true, and her measurement will tell us if she >>>>> belongs to a world with “spin” down or up, she will automatically know >>>>> that whatever Bob she will meet, will have the corresponding results, no >>>>> action at a distance here. >>>> >>>> Again, you keep referring to this non-existent infinity of worlds — >>> >>> “worlds” would be better. >>> >>>> a notion that has nothing to do with Everett or his interpretation of >>>> quantum theory. "... She will automatically know that whatever Bob she >>>> will meet, will have the corresponding results...". This is precisely the >>>> question that you have not answered -- how does this happen? >>> >>> Because in ALL “worlds” Alice and Bob have they spin described by the >>> no-separable singlet state. The statistics seems non-local, due to their >>> ignorance of which partition of the wave function they belong to. >> >> No, due to the fact that any any "world" in which they find themselves the >> correlations indicate non-locality. > > Yes, but not any action at a distance. > > > >> >>>> What is the particular magic that you put in the mix to ensure that the >>>> correct correlations emerge? >>> >>> Only QM, without collapse. >> >> That is truly magical, and you have no evidence for this whatsoever. > > It follows from both QM and Comp. If Alice and Bob are space-separated, I > cannot even makes sense of how you can measure correlations, given that once > they are separated, whatever result they got, will be shared with different > Alice and Bob in different branch. > > Bruno, please get a clue. In Bell experiments Alice and Bob are NOT > space-separated.
Only when they prepare the singlet state, but then they separate. > They are in the same laboratory! It's from the correlation results that > action at a space-separated "influences" is INFERRED. It was Bell's theorem > that allowed such experiments to be done, since prior to that, and presently, > and forever, it's IMPOSSIBLE in principle to space-separate Alice and Bob, > and do measurements on both. AG That is exactly what did aspect. To measure simultaneously, relatively to the laboratory frame the two entangled photons. > > I am not even sure we can define what could be an action at a distance in the > quantum formalism. > > > It means, for the singlet state, that conservation of spin angular momentum > is conserved for space-separated events. Not saying I believe it, but that's > what it MEANS. AG I knew that, but I suspect space and time and space/time to be quantum phenomenon. > > The notion does not even makes sense when we assume special relativity. The > only reason to believe this is the habit to think that there is only one bob > and one Alice, > > To believe there are additional Alice's and Bob's is ridiculous on its face. > Admit it! AG On the contrary. I claimed this before having heard of foundational problem in physics. It is provable in al possible mechanist theories of brain. You cannot make a machine disappear from arithmetic, like you cannot make a number disappear. Bruno > > which makes no sense once separated, unless they are correlated with a third > observer, but then, again by looking at the wave without collapse, there will > be no action at a distance. The no locality is only an appearance due to the > fact that we belong to infinities of histories, and cannot known which one we > are in. > > 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 >> <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] > <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.
