> On 25 Nov 2019, at 22:53, Bruce Kellett <bhkellet...@gmail.com> wrote: > > On Tue, Nov 26, 2019 at 1:31 AM Bruno Marchal <marc...@ulb.ac.be > <mailto:marc...@ulb.ac.be>> wrote: > > On 22 Nov 2019, at 08:35, Bruce Kellett <bhkell...@optusnet.com.au > > <mailto:bhkell...@optusnet.com.au>> wrote: > > > > I have been reading Sean Carroll's book "Something Deeply Hidden". It is > > more reasonable than some of the commentary had led me to believe. The > > issue at the moment is whether or not all things happen in the quantum > > multiverse. I argued that just because I might turn left at some point, it > > does not follow from Many-Worlds QM that in some other world I turn right. > > Absolutely. That follows directly from the Schroedinger equation. That is why > we take life instead of jumping out of the window! On the contrary the > linearity and decoherence assures us that when we take a decision, we acts > similarly in all universe, unless the decision use a quantum coin of course. > > > > Carroll agrees with this, despite some reports to the contrary. On page 214 > > he says "No, you do not cause the wave function to branch by making a > > decision.... Branching is the result of a microscopic process amplified to > > macroscopic scales: a system in a quantum superposition becomes entangled > > with the environment, leading to decoherence. A decision, on the other > > hand, is a purely macroscopic phenomenon. There are no decisions being made > > by the electrons and atoms inside your brain; they're just obeying the laws > > of physics.” > > OK. Of course, we can branch if we desire to do so, like deciding to take > the holiday in the North or in the south by untangling that decision with a > quantum coin. > > > > > So there is not a coy of me in some other branch that is typing a > > completely different email at this moment..... > > > > Carroll also says sensible things about quantum suicide and other moral > > issues. > > > > I was, as Brent also reported, a little surprised by his argument that it > > didn't really matter whether you thought of the splitting of the wave > > function/universe on a decohered quantum event as spreading at light speed, > > or as instantaneous throughout the entire universe. (pp. 170-171). I think > > this reflects the fact that Carroll does not seem to be as opposed to the > > idea of non-locality as are other advocates of many worlds. However, he > > does seem to think that the fact that outcomes of experiments are not > > unique in many-worlds does deflect the impact of Bell's theorem in that > > theory. "That doesn't mean that Bell's theorem is wrong in Many-Worlds; > > mathematical theorems are unambiguously right. It just means that the > > theorem doesn't apply. Bell's result does not imply that we have to include > > spooky action at a distance in Everettian quantum mechanics, as it does > > for boring old single-world theories. The correlations don't come about > > because of any kind of influence being transmitted faster than light, but > > because of branching of the wave function into different worlds, in which > > correlated things happen." (p. 105) > > I agree with Carroll. I guess you don’t ... > > No, as I say. One problem is that his stance on decoherence spreading > instantaneously is at variance with his rejection of Bell non-locality.
Yes, that is weird. > Actually, Carroll's ambivalence towards non-locality is even more evident in > the latter part of his book, where he attempts to find space-time emerging > from entanglement. He has to acknowledge that entanglement is intrinsically > non-local, in that it mixes the wave function at one point with that at > another. And the points that are entangled act as a unit, even though widely > separated -- with no intervening physical processes. > > On page 233, he distinguishes between two senses of "locality": what we might > call 'measurement locality' and 'dynamical locality'. The EPR thought > experiment shows that there is something that seems non-local about quantum > measurement. ... Whether many-worlds is non-local in this sense depends on > how we choose to define our branches of the wave function: we're allowed to > make either local or non-local choices, where branching happens only nearby > or immediately throughout space. > Dynamical locality, on the other hand, refers to the smooth evolution of > the quantum state when no measurement or branching is happening....This kind > of locality is enforced by the rule in special relativity that nothing can > travel faster than light. And it's this dynamical locality that we're > concerned with at the moment as we study the nature and emergence of space > itself." (p. 233) > > I think this whole section is rather confused and this is little more than > sophistry. Sean is trying to cover up what is really a glaring inconsistency > in his approach. Maybe more work will enable one to make a bit more sense of > this…… Let us hope. I still don’t see any FTL influence in the MWI, as I conceive it, but I know we do differ on how to interpret the wave. More on this later perhaps. > > > > > > I think this is wrong, of course. > > … as you say. > > > > > The trouble with this argument is that deflecting Bell's theorem does not > > automatically mean that your theory is, in fact, local. > > I agree on this. But why would it be non local? > > Because, the wave-function itself is non-local -- it contains entangled > particles that are widely separated in space. That is the definition of > non-locality! I am not sure. I use “non-locality” for “FTL physical influence”. In the MWI, some particles can be entangled but without implying any possible FTL when we do measurement on them, except from the local point of view, due to our ignorance of all terms of the wave. It means simply that Alice and Bob belongs to the same branch of history/reality. > > > And, as is usual for many-worlders, Carroll does not go on the actually > > spell out how the magic of world branching actually gives rise to the > > observed correlations. (He can't, of course, and that is why the issue is > > glossed over.) Maudlin, on the other hand, is so pissed off with people > > thinking that they can subvert Bell's theorem, that he simply states baldly > > that the quantum mechanical wave function is intrinsically non-local > > (Philosophy of Quantum Theory, 2019). > > I will wait for a proof of this statement. > > I suggest you read Maudlin's new book, or even the second edition (2011) of > his earlier book on Quantum Non-Locality and Relativity. As I have often > said, the singlet state of two entangled spin-half particles is intrinsically > non-local because it is a single quantum state that refers to two distinct > spatial locations. This is true for any entangled state -- it refers to two > or more spatial locations simultaneously, which is the definition of > non-local. Then we might agree, if you agree that this does not entail any FTL actions. 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 everything-list+unsubscr...@googlegroups.com > <mailto:everything-list+unsubscr...@googlegroups.com>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/CAFxXSLSxMNQ%3DFfBtbzCO9Q1%2BavHbr%3DOufygFyKWHYYynY_fAsA%40mail.gmail.com > > <https://groups.google.com/d/msgid/everything-list/CAFxXSLSxMNQ%3DFfBtbzCO9Q1%2BavHbr%3DOufygFyKWHYYynY_fAsA%40mail.gmail.com?utm_medium=email&utm_source=footer>. -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/594E94F8-92BC-43D9-A148-D900487DC19B%40ulb.ac.be.
