Bruno et al: I think *"definiteness"* is always counterfactual since it *MUST* deny the potential influences from unknown factors (domains, a/effects, even some definitely counterfactual influences we do not recognize as such at all). It is a consequence of our agnostic view (as I recall: we agreed on such, at least to some degree) and our (accepted?) view on 'scientific' - as doubtful. I mean the 'counterfactual' mildly: it "counters" the factual *TOTAL* impact, not necessarily negating all the infuences. Our views are partial at best.
I do not know much about rhe QM-related readings and am too old already to start learning. I accept my ignorance and try to live with it as long as I can. John Mikes On Sun, Apr 17, 2016 at 1:42 PM, Bruno Marchal <[email protected]> wrote: > > On 16 Apr 2016, at 01:46, Bruce Kellett wrote: > > On 16/04/2016 12:20 am, Bruno Marchal wrote: > > On 14 Apr 2016, at 14:31, Bruce Kellett wrote: > > It is interesting that you have not answered my question about what > exactly you mean by 'counterfactual definiteness' so that we know what you > mean when you say that a theory is not counterfactually definite. > > > It is hard to define, especially if we avoid being technical. But we have > a good example: QM-with-collapse (or QM with a single universe). Like > Einstein already explain at the Solvay Meeting: if QM (with a single > universe) is correct, we can't ascribe an element of reality knowing a > result that we would obtain with certainty if we would make some > measurement, but will not do. Then Kochen and Specker proved that QM (+ a > single universe) is precisely like that. The proof does not apply to the > many-world, although it might apply to some too much naive rendering of the > many world (notably if we interpret wrongly the singlet state as I have > explained in previous post). > > > I do not understand what you are saying. Are you claiming that ordinary QM > with collapse is counterfactually definite because Einstein realism does > not apply? > > > > > > I say the contrary: t is NOT counterfactual making Einstein realism not > able to be applied. > > > > > > > > I.e., we cannot know with certainty what would have been the outcome of an > experiment that was not performed? (This is also the consequence of the > Kochen-Specker result that no set of hidden variables can predict the > results of all possible spin measurements on a spin 1/2 particle.) I would > have thought that this was one possible definition of counterfactual > *indefiniteness*. > > > I would be OK too. > > > > > What additional fact about MWI changes this conclusion? > > > None. Except that with a single physical reality that counterfactualness > entails non locality, but the same conunterfactualness with eother > computationalism and/or QM-without collapse does not entail physical nopn > locality, but only its statistical *appearances* in the memory of the > machine testing it. > > > > > Since in MWI all possible experiments are performed in some word or other, > I would have thought that experimental outcomes are available for all > possible experiments -- nothing is *actually* indefinite > > > It is relatively to you knowledge of a state. If you measure the position > very precisely, you "soul" is attached to an infinity of > "body/representation" with many definite, but different, momenta. > > If you measure something the result is definite only relatively to one > representation among many. If you look at the transfer of information in > the 3p picture of the entire quantum teleportation, you can see that the > information is spread locally at all times. It is even somehow made > explicit if you are using Bob Coecke's use category to describe such > quantum events. > > http://arxiv.org/abs/quant-ph/0402130 > http://arxiv.org/abs/quant-ph/0402014 > > -- even though not all outcomes occur in this one world that we happen to > inhabit at the moment. > > > There is no real sense to say that we inhabit a world. We are all the > times in an infinity of worlds/situation, which differentiate or not > relatively to what we interact with. > An electronic orbital is a sort of map of the set of all words we are > relatively to the possible energy of that "electron". > But by the linearity of the tensor product, we share the worlds only with > the person we interact with. > You might look at the Rubin's paper (provided by Scerir). Or Bob's Coocke. > > I will comment your other post with more detail perhaps later. But I do > not really grasp your > > << > A and B perform their measurements at spacelike separation, but each > chooses the measurement orientation outside the light cone of the other. > There are four possible combinations of results, corresponding to four > worlds in the > MWI: |+>|+'>, |+>|-'>, |->|+'>, and |->|-'>. > Since each observer has a 50% chance of getting |+> and 50% of getting > |->, and the two measurements are completely independent of each other, it > would seem that each of these four worlds is equally likely. > >> > > The expressions |+>|+'>, |+>|-'>, |->|+'>, and |->|-'> does not describe > the superposition in which the observer will self-localize in: it is not > the singlet state, which describe an infinity of worlds where all pair of > particles of Bob and Alice are correlated. > The whole point is that the result of the measurement does not describe > the state we measure, but the partition of the sort of worlds to which we > *relatively* belong. > It is a bit long to verify by hand, but the linearity of tensor products > and of the evolution makes the correlated state remaining correlated, and > when one of them make a measurement, it just tell Bob in which partition of > the multiverse he *and "his" Alice" belong. > Only if the states of Alice and Bob electron where counterfactually > definite before the measurement would this entail a crazy spooky action at > a distance. You talk like if Bob or Alice are well defined relatively to > each other, but that is not the case: they both get random event, just > correlated in all universes, and they can't know which one it is, only the > partition of the multiverse given by the singlet state. > > 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]. > 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. > > > http://iridia.ulb.ac.be/~marchal/ > > > > -- > 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. > -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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