On Friday, November 17, 2017 at 3:18:39 PM UTC-7, Bruce wrote: > > On 18/11/2017 12:10 am, Bruno Marchal wrote: > > On 15 Nov 2017, at 22:26, Bruce Kellett wrote: > > On 16/11/2017 1:55 am, Bruno Marchal wrote: > > On 15 Nov 2017, at 00:55, Bruce Kellett wrote: > > On 15/11/2017 12:47 am, Stathis Papaioannou wrote: > > On Mon, 13 Nov 2017 at 8:54 am, Bruce Kellett <[email protected] > <javascript:>> wrote: > >> >> I don't think you have fully understood the scenario I have outlined. >> There is no collapse, many worlds is assumed throughout. Alice splits >> according to her measurement result. Both copies of Alice go to meet >> Bob, carrying the other particle of the original pair. Since they both >> have now met Bob, the split that Alice occasioned has now spread to >> entangle Bob as well as the rest of her environment. So there are now >> two worlds, each of which has a copy of Bob, and an Alice, who has a >> particular result. Locality says that Bob's particle is unchanged from >> production, so when he measure its spin, he splits into two copies, >> according to spin up or spin down. Since Alice is standing beside him, >> she also becomes entangled with his result. But Alice already has a >> definite result in each branch, so we now have four branches: with >> results 'up-up', 'up-down', 'down-up', and 'down-down'. However, only >> the 'up-down' and 'down-up' branches conserve angular momentum. How do >> you rule out the other branches? > > > When you put something in the cupboard and come back later to get it, why, > under MWI, is it still there? > > > I don't understand the significance of your question. Why wouldn't things > remain stable in MWI? After all, the whole world, as it is, becomes > entangled with the particular branching event. > > > OK, but not instantaneously. This might be the point where we disagree in > the interpretation of the Non-collapse theory. > > > I think that the general idea is that the entanglement with the result > spreads at the velocity of light -- inside the forward light cone. This > spread of entanglement does not require that all objects in the forward > light cone have explicitly interacted with the original event. The > mathematics are quite clear on this point. > > > You are right. So you might need an experience like Mandel & Co(I will > look at the reference, I guess you see which experience I allude to) where > two distant lasers create a singlet state non locally. That one has made me > doubt that MW could avoid Action-at-a-distance, and some thought experience > by Lucien Hardy too, but eventually, I remain unconvinced, > > > You will have to give more precise references. Searching on these names > throws up so many papers that it is impossible to sort out exactly what you > mean here. > > because wherever are the actors, the singlet state never describes a > non-local affair, it only predicts the result of the people who will met at > some time. > > > The singlet state is intrinsically non-local. >
But as Brent claims, and I think he is correct, there is a basis in which the singlet state is a eigenfunction. In that basis, the obvious non locality may not be so obvious, if indeed it exists. AG > It actually has nothing to do with whether people meet or not - it > describes a situation which explicitly violates Einstein's notion of local > realism: the state of one of the entangled pair is not separable from the > state of the other distant particle. Non-separability here implies > non-local influence, or simple non-locality. The attempt to claim that > non-separability does not imply non-locality is mere verbal gymnastics, > with no physical content. > > 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.
