On 21/11/2017 12:22 am, Bruno Marchal wrote:
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.
No, as I pointed out in my original post, a local hidden variable
explanation for the time-like correlations is available. That would mean
no more than that QM is incomplete. The problem is that this explanation
is not available in the space-like case, and you cannot use one
explanation in one place when it doesn't work elsewhere. When the
singlet particles are produced before separation, they cannot know
whether they are going to be measured at space-like or time-like
separations: any hidden variables that are going to explain the
correlations by some common cause mechanism have to be set in place from
the start. That is ruled out by simple logic given the time-like
violations of angular momentum conservation.
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.
That is just false.
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.
You clearly have not grasped the implications of my argument. The idea
that "MWI replaces all nonsensical weirdness by one fact (many
histories)" does not work, and is not really an explanation at all --
you are simply evading the issue.
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.
