http://mccabism.blogspot.be/2010/10/many-worlds-and-quantum-fungibility.html
<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> Virus-free. www.avg.com <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> 2017-06-08 12:57 GMT+02:00 Quentin Anciaux <allco...@gmail.com>: > > > 2017-06-08 12:40 GMT+02:00 Bruce Kellett <bhkell...@optusnet.com.au>: > >> On 8/06/2017 7:52 pm, David Nyman wrote: >> >> On 8 Jun 2017 1:05 a.m., "Bruce Kellett" < <bhkell...@optusnet.com.au> >> bhkell...@optusnet.com.au> wrote: >> >> >> The question then, is whether many worlds can provide a fully local >> account of this situation. I claim, with most present day physicists, that >> MWI does not provide any such local account. >> >> >> I suspect I'm being obtuse in some way here but, rereading the quote >> attributed to Bell himself by Wikipedia about superdeterminism, it strikes >> me that MWI seems to describe a species of this sort of thing. IOW when >> Alice and Bob make their measurements, the consequence in terms of branches >> is a spectrum of all the possible outcomes. Indeed one could say that this >> is what has been propagating from one to the other, rather than a >> 'particle'. Let's say then that the various versions of Alice and Bob that >> consequently coexist in MWI terms, however far apart they may have been, >> eventually meet to compare notes. Again, the spectrum of possible outcomes >> implicit in the global MWI perspective travels with them, as it were. >> However, of all the possible pairings of the two, it appears to be >> 'superdetermined' that each observed encounter must be consistent with the >> predictions of QM. And so it would appear that the paired results of their >> joint measurements are somehow inseparable, in Wallace's language, without >> there having been any action at a distance. If this depiction were to make >> any sense, one might then enquire what common cause, or other explanatory >> device, could account for this apparent superdetermination of observed >> outcomes? >> >> >> I don't think that superdeterminism and MWI have very much in common. >> Although Bell did acknowledge that superdeterminism provides a possible >> local loophole to his theorem, Bell always thought that superdeterminism >> was sufficiently implausible to be disregarded as a serious contender as an >> explanation. >> >> I tend to agree with the comment from Zeilinger on the same Wiki page, to >> the effect that such absolute superdeterminism would render the whole >> scientific enterprise otiose. I think that non-locality is a better >> approach -- at least then science can still make sense. >> >> The problem with attempts to find local accounts of the correlations >> between Alice and Bob is that their measurements are taken to be >> independent. If they are independent, then they cannot be correlated -- >> that is in the definition of independence. Superdeterminism circumvents >> this, simply by denying that Alice and Bob can freely choose their >> measurements, and are consequently not independent. >> >> As I understand the better attempts to give an account in MWI, it is >> accepted that Alice and Bob are independent, so their results are >> uncorrelated *when they are made*, but the necessary correlation is built >> later when they meet to compare results. I find this unconvincing, and no >> satisfactory account of any mechanism whereby this could be achieved has >> been given. Accounts along this line seem to depend on multiple worlds >> containing all possible results that somehow, miraculously, pair up, >> without any outside intervention, in such a way to give the necessary >> correlations. This is rendered less plausible if one considers timelike >> separations, where Bob, say, is always in Alice's forward light cone, so >> any splitting of either observer is communicated to the other by normal >> decoherence, long before the other measurement is made, and before they >> meet up to compare lab books. >> >> > If I remember David Deutsch explained that the worlds were not "splitting" > but differentiating, and thus are all preexisting... so even if their > measures are independent, this gives only a self localisation... and so > nothing non-local happens ? > > Quentin > > > > > >> 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 everything-list+unsubscr...@googlegroups.com. >> To post to this group, send email to everything-list@googlegroups.com. >> Visit this group at https://groups.google.com/group/everything-list. >> For more options, visit https://groups.google.com/d/optout. >> > > > > -- > All those moments will be lost in time, like tears in rain. (Roy > Batty/Rutger Hauer) > > > <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> > Virus-free. > www.avg.com > <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> > <#m_-5974564936490926854_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> > -- All those moments will be lost in time, like tears in rain. (Roy Batty/Rutger Hauer) -- 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 everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
