On 17 Nov 2017, at 23:11, Bruce Kellett wrote:
On 18/11/2017 12:04 am, Bruno Marchal wrote:
On 15 Nov 2017, at 22:10, Brent Meeker wrote:
On 11/15/2017 7:04 AM, Bruno Marchal wrote:
On 14 Nov 2017, at 21:15, Brent Meeker wrote:
On 11/14/2017 6:18 AM, Bruno Marchal wrote:
On 13 Nov 2017, at 22:40, Bruce Kellett wrote:
On 14/11/2017 2:07 am, Bruno Marchal wrote:
On 12 Nov 2017, at 23:05, Bruce Kellett wrote:
What really annoys me is the continued claim that many
worlds eliminates the need for non-locality. It does not,
and neither Bruno nor anyone else has ever produced a valid
argument as to how many worlds might restore locality.
But nobody has proved that there is non locality in the MWI.
EPR-BELL proves non-locality apparant in each branch, but the
MWI avoids the needs of
action at a distance to explains them. Once Alice and Bob are
space-separated, their identity are independent. It makes no
sense to talk of each of them like if they were related,
(unless you correlate them with a third observer, etc) If
they do measurement, some God could see that they are indeed
no more related, but if they decide to come back to place
where they can compared locally their spin, they will always
get contact to the corresponding observer with the well
correlated spin. The independent Alice and Bob will never
meet because they can't belong to the same branch of the
multiverse, by the MWI of the singlet state. So Mitra is
right. Although Bertlmann's socks are tyically not working
for Bell's violation in a MONO-universe, it works again in
the MWI, applied in this case to the whole singlet state.
Bell has proved non-locality in MWI, every bit as much as in
each branch separately. You appear not to have grasped the
significance of the scenario I have argued carefully. Alice
and Bob are not space-like separated in the scenario I
outlined. Alice and Bob are together in the same laboratory
when the second measurement is made. They are necessarily in
the same world before, and branch in together according to
Bob's result. Your mumbo-jumbo about them only being able to
meet in appropriate matching branches does not work here,
because they are always in the same branch. And there is no
reason to suppose that their results in some of those branches
do not violate conservation of angular momentum.
I have no clue what you mean. The singlet state guaranties the
conservation of angular momentum in all worlds. The singlet
state describes an infinity of "worlds", and in each of them
there is conservation of angular momentum, and it has a local
common cause origin, the same in all worlds.
But it's not a sufficient 'hidden' variable to explain the space-
like correlation of measurements.
If the the explanation is based on hidden variable, per branch,
then there will be non-locality. But the many universe are not
really hidden variable in the sense of EPR-Bell's, which assumes
Alice and Bob have the same identity and keep it, when they do
the space-like measurement, but it seems to me that this is a
wrong interpretation of the singlet state when we suppress any
possible collapse. If Alice and Bob are space-like separated,
they will later only access to the Bob and Alice they will
locally be able to interact with, and those are "new" people, not
the original couple.
But that's the point of Bruce's version in which the measurements
are time-like. Alice and Bob will have continuity of identity
and, as he argues, the explanation for the correlation of results
being stronger than classical must be the same.
But there are the same. The singlet state explains this too. The
mystery is in the apparent space-like separation, where it looks
like a physical action at a distance plays some role, except that
this has not been proved in the MW theory.
Again you appeal to the 'apparent space-like separation'. As Brent
said, the point of my time-like example was that there is no space-
like separation at any time, so that escape is not available to you.
Without space-like separation, I don't see why invoke a physical
action at a distance at all.
And exactly what is it that you claim has not been proved in MW
theory? Bell's theorem applies there too: it has never been proved
that it does not.
EPR and Bell assumes unicity of outcomes, or the collapse. Without
this, the "spliting/differentiation" of consciousness/universe becomes
a local phenomenon, and the formalism ensure locality.
Bell was no fool: he did not like MWI, but if that provided an
escape from his theorem, he would have addressed the issue.
He did not. He arguably made something worst: reinterpretating the
Many-world in term of a local hidden variable theory.
The fact that he did not suggests strongly that you do not have a
case.
That is not a convincing argument. I just do not see any non-locality
derivable from the SWE-without-collapse. Indeterminism also go away in
the MWI. The MWI replace all nonsensical weirdness by one fact, which
is trivial with mechanism: we are in may "histories", and cannot
decide which one.
Bruno
Bruce
In another post, you say that decoherence is statistical. may be
that is where we disagree. decoherence is only entanglement with
the local environment (spreading/differentiating at the speed of
light).
Bruno
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