From: *Bruno Marchal* <[email protected] <mailto:[email protected]>>
On 1 Aug 2018, at 06:19, Bruce Kellett <[email protected]
<mailto:[email protected]>> wrote:
No, there are not any infinities of anything. You simply confuse
yourself by continuing to claim such things which are not part of
quantum mechanics.
The singlet state just means that They will see correlated result
when coming back together. Let me put it in this way: if Alice and Bob
are space separated, I do not see how to give meaning to “to be in the
same branche”, and they might individually get non correlated spin
measurement?
It is easy to see how they can be in the same branch, even if space-like
separated. I gave an account of how all measurements are made in the
same branch by starting with the time when Alice and Bob meet to compare
notes after their series of experiments and working backwards to show
that, since neither can jump between branches, all measurements must
have been made in the same branch.
You can do the same thing in the forwards time direction by considering
that the singlet is prepared in one world. The component particles move
off in separate directions, but they can't jump worlds either, so when
Bob gets his particle to measure, he is necessarily in the same world as
that in which Alice makes her measurement -- the singlet state itself
guarantees that. Then they make their measurements: each gets either up
or down, so each splits into two branches. But the branch with, say,
Alice_up is connected with the original branch in which Bob sits. He
splits into two branches on measurement, but again, each branch is
connected with the original Alice branches. There are now four branches:
Alice_up-Bob_up, and so on for the other combinations. Each of these
branches defines a single world in which there are a pair of
measurements. And, because of the way in which these branches are always
interconnected, the results of each experimenter, if repeated many
times, will always have the correct quantum correlations. There are no
other branches -- and no unconnected measurements that have, somehow, to
be discarded -- they can never get uncorrelated spin measurements!
Bell’s inequality will not been violated, because that Bob and Alice
will never meet again. Each of them will meet only their relevant
counterparts when they will “meet again”.
and all what they both know is that they share some historical
reality with a relative partner, so that their simps are correlated,
but they are are ignorant and thus distributed on infinitely many
histories, with all the correlation between different spin “angle”
(assuming a fixed base to describe them).
I might be wrong, but the violation of Bell’s inequality (or
Kochen-Specker theorem) does not entail any physical instantaneous
action at a distance. I have seen may attempt to prove this, but
they always favour a branch in a way or another, forgetting the
probabilities bear on different portioning of the multiverse in the
big picture.
Any evaluation of a set of correlations between experimental results
happens in one branch of the superposition. So much for "favouring a
branch in a way or another." There is simply no other way to evaluate
the correlations. There is no "big picture" that is going to change
this conclusion.
Then you assume some collapse.
As usual, that is your fantasy (i.e., a meaningless bolt-hole by which
to escape an inevitable mathematical conclusion). No collapse is assumed.
It makes the whole physics becoming covariant, despite necessary
relative local appearance of what seem to be an action at a
distance. There are none, but to show this, we must take into
account the fact that Alice and Bob find all correlated results in
all directions.
Physics is covariant in any case. The non-locality is real -- it is
not just an 'appearance'. Bell's theorem and the observed
correlations prove this.
I don’t see this. The violation of Bell’s inequality is real, but
without any collapse, all interactions are local, and spread locally
fro the place where they have been done. That follows from the wave
only, and that guaranties that Alice and Bob, when coming back, will
see the correlation/violation, but Alice and Bob does that only with
some relative counterpart of Bob and counterpart of Alice respectively.
You keep returning to this idea of a "common cause" explanation. And
that, as we know, is ruled out by Bell's theorem. And all attempts to
undermine Bell's theorem end in disaster -- Bell's theorem is called a
theorem for good reason.
Like Maudlin says: “Or finally once can both avoid collapses and
retain locality by embracing the Many-Minds ontology, exacting a high
price from common sense”.
That refers directly to the "many-minds" interpretation of QM. And
Maudlin, as well as everyone else, has long since moved on from this
position. You should go to the library and read the third edition of
Maudlin's book for his more recent position.
Bruce
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