> On 2 Dec 2019, at 12:06, Bruce Kellett <bhkellet...@gmail.com> wrote:
> On Mon, Dec 2, 2019 at 8:08 PM Bruno Marchal <marc...@ulb.ac.be 
> <mailto:marc...@ulb.ac.be>> wrote:
> On 29 Nov 2019, at 00:50, Bruce Kellett <bhkellet...@gmail.com 
> <mailto:bhkellet...@gmail.com>> wrote:
>> On Fri, Nov 29, 2019 at 1:27 AM Bruno Marchal <marc...@ulb.ac.be 
>> <mailto:marc...@ulb.ac.be>> wrote:
>> On 26 Nov 2019, at 22:39, Bruce Kellett <bhkellet...@gmail.com 
>> <mailto:bhkellet...@gmail.com>> wrote:
>>> On Wed, Nov 27, 2019 at 12:27 AM Bruno Marchal <marc...@ulb.ac.be 
>>> <mailto:marc...@ulb.ac.be>> wrote:
>>> On 25 Nov 2019, at 22:53, Bruce Kellett <bhkellet...@gmail.com 
>>> <mailto:bhkellet...@gmail.com>> wrote:
>>>> 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”.
>>> That is just an abuse of language. Non-local means "not local", i.e., not 
>>> all in one place.
>> Then even Newton Universe is non local. 
>> Yes Newton was aware of this.
>>> Some attempt has been made to replace the term "non-local" with the term 
>>> "non-seperable”.
>> Yes, notably d’Espagnat. It avoids the confusion with the Eisnsteinian 
>> non-locality, which requires FTL (cf the “spooky action at a distance”), 
>> which must exist in QM + the assumption of a unique universe.
>>> I think we can all agree that the singlet wave function is non-separable -- 
>>> it cannot be written as a simple product of two terms, one referring to 
>>> each particle.
>> Yes, we agree on this.
>>> I maintain that it is also non-local, in that the two particles are at 
>>> different locations (locales). Non-local can have no other meaning in 
>>> ordinary linguistic usage.
>> I invite you, and Alice, and I give you an envelop to each of you. You are 
>> told that one contain a piece of paper with O inscribed on it, and the other 
>> with one. Then you go in different galaxies, say, and open it. Once you see 
>> 0 (res. 1) you know that Alice will see 1 (res. 0). This seems non local in 
>> your sense, where most would agree that in this case, there is no 
>> “non-locality” issue. What I claim is that in the Everett theory, all 
>> non-locality are of that type.
>> That non-loclality has a common cause explanation. Like Bertlmann's socks, 
>> there is no mystery here. The problem is with entangled systems, where 
>> non-separability means non-locality that has no common cause explanation, 
>> even in many-worlds theory.
> I doubt this. The MWI reduces the non-separability of the probabilities into 
> an equivalent with Bertlmann’s socks, still keeping the violation of Bell’s 
> inequality justifying the appearance of non-locality. 
> The devil is in the detail. And you have still not provided any detail.

You are the one who seem to believe in some FTL physical action (not just the 
quantum inseparability), and that indeed follows clearly from the “one-world” 
assumption. Then with mechanism, we get 0 universes, but infinitely many 
relative histories, structured by self-reference. 

>>> 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.
>>> The trouble with this hope is that it no local account of the EPR 
>>> correlations been realised in any coherent mathematics. Bell's theorem 
>>> rules it out: no local hidden variable account of the EPR correlations is 
>>> possible in any theory, whatsoever. It is a no-go theorem; it proves a 
>>> negative -- something is impossible. Many-worlds does not subvert Bell's 
>>> theorem.
>> That is right. But the violation of Bell’s inequality entails FTL only when 
>> one world is assumed, with well defined outcome for all measurement, or put 
>> in another way, assuming a unique reality, with one Bob and one Alice, but 
>> Bell’s reasoning does not prove FTL influence in The many-worlds, where all 
>> outcomes are obtained, and propagate between diverse Alice and Bob locally, 
>> leading to the apparent violation of Bell’s inequality, but without FTL.
>> Bell did not assume a collapse. His is a mathematical result, where the only 
>> assumption is locality. As usual, if you think there is a local explanation 
>> of the EPR correlations in many-worlds, then produce it.
> We differ only on the way we interpreted the wave and the worlds. The singlet 
> state is … local! It does not entail any correlation between the Alices and 
> the Bobs. It enforces only that the Alices and Bobs can meet only their 
> corresponding correlated partners, among the infinitely many Alices and Bobs 
> (most of them being not accessible from each others).
> The singlet state is non-separable, and hence non-local when Alice and Bob 
> are separated.

I don’t know which difference you make between non-separable and non-local.
With "one world", both requires FTL actions, but not so with many histories, 
where a non separable state just means that we differentiate into multiples 
histories verifying some internal correlations. I agree with LC that eventually 
the entire notion of space will be explained by such (qubit) entanglements.

> The rest of you comment here is without meaning.


> You have to flesh it out, and your reluctance to do so convinces me that you 
> cannot. You are just hoping for a miracle.
>>> I think it is becoming generally accepted in the physics community that the 
>>> entangled state is intrinsically non-local: acting on one part of it 
>>> affects the rest, even across the entire universe.
>> That would mean some FTL actions, but I very much doubt this.
>> No, there is no need of FTL. For example, in the third (2011) edition of his 
>> book 'Quantum Non-Locality and Relativity', Maudlin shows that Flash GRW 
>> theory, as developed by Temulka, gives a perfectly relativistic account of 
>> the EPR correlations without any FTL action.
> This astonishes me. If you have a link I could try to see if this makes 
> sense, but, to be sure, I am not enthusiast at all on the GRW theory, which 
> is new QM theory. If some measurement affects the rest of the Universe 
> instantaneously, I think that imply FTL (without signals, but still with a 
> physical influence). 
> I only know this from Maudlin's books. There is a detailed account in his 
> recent book, "Philosophy of Physics: Quantum Theory" (Princeton, 2019).

I will plausibly order that book.

> The paper that Phil referenced: Esfeld and Gisin (arXiv:1310.5308) contains a 
> summary and discussion, even though those authors are not convinced by the 
> theory.
> I must admit that Flash GRW is not an approach that I find convincing either. 
> The ontology of this theory is the flashes themselves, the wave-function is 
> not part of the ontology, so the collapse is entirely epistemic, and just 
> like the "collapse" in classical probability theory. It works, but may not be 
> convincing to everyone, since the ontology is remarkable thin!
> The real problem is, as ever, that despite many promises, many-worlds theory 
> does even less well in that it offers nothing in the way of an explanation.

The partial computable histories belongs already to elementary arithmetic, 
assumed by all scientists and philosophers. The problem is not in explaining 
the many “worlds/histories”, but the appearance of a stable and sharable “long 

I worked on that problem well before even knowing that Everett type of QM 
existed already.

> Maudlin's recent book discusses many worlds, but he concentrates on the 
> problems with this idea, and essentially is not convinced that many-worlds 
> makes sufficient sense in its own terms to provide an explanation for 
> anything. Sean Carroll, in his recent book "Something Deeply Hidden", also 
> evades the question. His discussion is on pages 104-105. He states that Bell 
> assumed "that measurements have definite outcomes”.

That is what I think too.

> Essentially, this is the assumption of counterfactual definiteness that has 
> often been proposed. Carroll then says that since many-worlds does not assume 
> that experiments have single outcomes, Bell's theorem doesn't apply. His 
> unspoken assumption here is that if many-worlds evades Bell's result, then it 
> can give a local account of the EPR correlations -- they happen "because of 
> branching of the wave function into different worlds, in which correlated 
> things happen." (p. 105) This is similar to your claim above, but it is not 
> an explanation. And even if Bell's theorem doesn't apply, it does not follow 
> that the theory can provide a local account of the correlations.You still 
> have to provide that account.

But it is “trivial”, for the reason that the locality is in the unitary 
transformation. The local account is in the Hilbert space or in the von Neuman 
Algebra. My account is modest, because I have to derived it from self-reference 
to distinguish the qualia and the quanta. Keep in mind that my goal is to put 
some light in the mind-body problem frame. 

> The other major source I can refer to is the book "The Emergent Multiverse" 
> by David Wallace (Oxford, 2012). This book is the most comprehensive account 
> of Everettian ideas currently available. Wallace also ducks the issue. In 
> sections 8.5-8.7 (pages 302-312) he gives a detailed account of the branching 
> structure that arises if Alice and Bob do independent spin measurements at 
> space-like separations. Then on page 310 he gives a general entangled 
> wave-function and points out that Alice's and Bob's measurements again lead 
> to splitting. But he then says: "In this case, the amplitudes of the four 
> sets of branches into which C [a central, neutral observer] eventually 
> branches are not determined simply by the separate weights of the branchings 
> at A and B. Nor is this to be expected: as I stressed previously, in 
> Everettian quantum mechanics interactions are local but states are nonlocal. 
> The entanglement between the particle at A and the particle at B is a 
> nonlocal property of the forward light cone of A and that of B. Only in their 
> intersection can it have locally determinable effects---and it does, giving 
> rise to the branch weights which, in turn, give rise to the sorts of 
> statistical results recorded in Aspect's experiments."
> This might sound good, but again, there is no detail. What exactly is 
> supposed to happen at the intersection of the forward light cones from A and 
> B? There is no interaction there -- any information that is made locally 
> present there was already present in the only relevant interactions, which 
> are the original measurements made by A and B; any branch weights that are 
> around are set there, exactly as in the case of non-entangled particles. 
> Wallace started out well, but ducked out at the last minute, and he failed to 
> give any comprehensible account that does not rely on simple magic.

I should read Wallace book. I am not sure I see that magic. There is an 
infinity of light cones, and in all intersection Alice and Bob have prepared 
entangled particles.  They are just both always unaware of their possible 
measurement results, and this makes them belonging to many of them, and that, 
normally, lift the QM predictions on each differentiated histories.


> So the best authorities available fail to give a local account of the EPR 
> correlations in a many-worlds setting -- they all simply duck the issue when 
> the rubber hits the road. Just as you routinely do.
> Bruce
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