From: *Bruno Marchal* <marc...@ulb.ac.be <mailto:marc...@ulb.ac.be>>
On 23 Apr 2018, at 13:10, Bruce Kellett <bhkell...@optusnet.com.au
<mailto:bhkell...@optusnet.com.au>> wrote:
From: *Bruno Marchal* <marc...@ulb.ac.be <mailto:marc...@ulb.ac.be>>
On 23 Apr 2018, at 05:43, Brent Meeker <meeke...@verizon.net
<mailto:meeke...@verizon.net>> wrote:
On 4/22/2018 6:50 PM, Bruce Kellett wrote:
From: *Brent Meeker* <meeke...@verizon.net
<mailto:meeke...@verizon.net>>
On 4/22/2018 9:19 AM, Bruno Marchal wrote:
It follows from both QM and Comp. If Alice and Bob are
space-separated, I cannot even makes sense of how you can
measure correlations, given that once they are separated,
whatever result they got, will be shared with different Alice
and Bob in different branch. I am not even sure we can define
what could be an action at a distance in the quantum
formalism. The notion does not even makes sense when we
assume special relativity. The only reason to believe this is
the habit to think that there is only one bob and one Alice,
which makes no sense once separated, unless they are
correlated with a third observer, but then, again by looking
at the wave without collapse, there will be no action at a
distance. The no locality is only an appearance due to the
fact that we belong to infinities of histories, and cannot
known which one we are in.
It depends on what you mean by "action at a distance". The
theory you are depending on for these pronouncements entails
that, on a MW picture, some of the possible worlds have
probabilities that go to zero as a result of an interaction at
Alice or at Bob. So an interaction at one of them changes the
probabilities at the other.
For Bruno, it seems that "non-locality" means "action at a
distance", where he interprets that to mean that there is some
superluminal transfer of information,
I prefer to distinguish non-locality (inseparability), action at a
distance, and transfer of information at a distance. Even in a
mono-universe theory, the action at a distance exists (by EPR-BELL)
but cannot be used to transfer information. But in the multiverse,
we have the inseparability, but we don’t have any
action-at-a-distance. At least that is what I am arguing for.
That is what you are arguing for. But you have not as yet put forward
any clear and convincing argument that you can succeed in your search
for such a theory. You have to take the accepted formalism for the
singlet state and develop a unitary theory that avoids non-locality.
I have recently reproduced the argument given by several MWI
advocates, and have shown that it does not avoid the non-locality
intrinsic to the non-separability of the singlet state wave function.
Your challenge is to start from the same state and apply unitary
evolution to reach a different conclusion.
I did it, and later I refer to Price simpler treatment. Deustch did
the same in the Heisenberg picture. See the answer by Saibal, I can
hardly do better
What answer by Saibal? He has not explained anything. As for Price, he
just did not see that he had built non-separability, and hence
non-locality, into his treatment. Deutsch tries to answer the case by
showing that information transfer is everywhere local. That is fine,
because that was never in dispute. He does not seem to realize that it
is the non-separability of the wave-function, not information transfer,
that lies at the heart of the issue, and he simply did not address the
real source of the non-locality; which is that the wave-function itself
vanishes for combinations of worlds that violate angular momentum
conservation. It is a property of the wave-function, not a property of
the number of "worlds" you consider, or the way information is conveyed
between experimenters.
Bruce
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