On 6/4/2016 11:39 PM, Bruce Kellett wrote:
On 5/06/2016 3:31 am, Bruno Marchal wrote:
On 04 Jun 2016, at 01:28, Bruce Kellett wrote:
Sure, Bell's theorem only rules out local hidden variables. If you
simulate non-local hidden variables (i.e., get the separated
experimenters to communicate non-locally), then of course you can
reproduce the quantum correlations. But I was under the impression
that the computationalist goal was to eliminate non-locality.
Separated experimenters, with as much computing power as necessary,
cannot simulate the quantum correlations by performing only local
computations.
You can simulate the whole (multiversial) structure, and the
observers will find that from their perspective, Bell's inequality
are violated. From outside, we can see (like Everett saw) that it is
just a case of self-duplication FPI. (Which brings us back to the
preceding thread of course).
I think you are trying to move the goal posts here.... The original
argument about non-locality in MWI was the contention by people like
Price, Tipler, Brown, and Christian that Bell made certain assumptions
that were not true in the Everetttian approach. Their conclusion was
that his theorem was not applicable to the MWI, rendering the argument
that local hidden variables were ruled out inapplicable in that case.
(Though Joy Christian tries to go further and argues that Bell made a
trivial mistake that rendered his 'theorem' invalid in all
interpretations.) I have rebutted the various claims of these papers
in other posts: Bell does not depend on such ill-defined things as
counterfactual definiteness, and certainly does not assume that
experiments have only single outcomes. My conclusion is that Bell's
theorem is valid universally -- merely changing the interpretation
does not alter that, and thus non-locality has been shown to be
intrinsic to quantum mechanics.
You are now attempting to change the argument: you appear now to
accept that individual experimenters will see the quantum world as
non-local, but that this is merely an observer-dependent effect,
arising from self-location in the multiverse: another instance of FPI.
I think that you have to do a bit more work on this changed approach
to non-locality: I think you will find that the argument does not work
like the FPI account of apparent indeterminism in a deterministic
universe. Bell's theorem applies to every set of correlations obtained
by experimenters in every branch of the universal wave function --
there is no 'external' perspective from which Bell' s theorem does not
apply. If there were, there would have to be a local account available
from the 'bird' perspective, and there is no such account. If you
claim that there is, then the onus is on you to produce that account.
The singlet state
|psi> = (|+>|-> - |->|+>)/sqrt(2)
is the wave function from the 'bird' perspective, and particles 1 and
2 are separated in the 'bird' perspective as much as in any 'frog'
perspective. Going outside the perspective of the individual
experimenters does not actually gain you anything in this instance.
I don't think anyone (except Joy Christian) argues that Bell's theorem
does not apply in MWI - I certainly don't think that. But I think that
"which universe" is a non-local hidden variable in MWI and so explains
the correlation without violating Bell's theorem.
Brent
--
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.
