On 18/04/2016 10:11 am, Jesse Mazer wrote:
On Sun, Apr 17, 2016 at 7:34 PM, Bruce Kellett
<[email protected] <mailto:[email protected]>> wrote:
The future light cones of the observers will overlap at a time
determined by their initial separation, regardless of whether they
send signals to each other or not.
Of course, I never meant to suggest otherwise. Imagining a central
observer who receives messages about each experiment was just
conceptually simpler than imagining an arbitrary system that is
affected in some unspecified way by each experimenter's results along
with every other part of that system's past light cone. But you
certainly don't *need* to use that particular example.
The issue is to find a local explanation of the correlations: appealing
to some arbitrary system that is affected in some unspecified way. But
my example shows that no exchange of information after the separate
worlds of the two experimenters have fully decohered can ever explain
the quantum correlations.
This so-called "matching up" is pure fantasy. Who does this
matching? If the central umpire is to do the matching, he has to
have the power to eliminate cases that disagree with the quantum
prediction. Who has that power?
The laws of physics would do the matching in some well-defined
mathematical way.
I agree that the laws of physics will 'prevent' the formation of any
worlds in which the laws of physics are violated. That is not the issue.
The issue is: how do the laws of physics act in order to achieve this.
Do they act locally or non-locally? If they act locally, then you are
required to provided the local mechanism whereby they so act. You are
not doing this at the moment.
I don't see this as fundamentally different from the fact that the
laws of electromagnetism can be written in a form where the electric
and magnetic potentials at each point in spacetime can be found by
summing the potentials from all the charges and currents on the entire
past light cone of that point (this neat approach is known as
'Lienard-Wiechert potentials', see
https://www.av8n.com/physics/lienard-wiechert.htm for some
discussion). Is it meaningful in that case to ask "who" is keeping
track of each individual charge or current on the past light cone and
adding up their potentials correctly to get the total?
If you don't yet see the difference, then you need to think about it a
bit more.
Also, what do you mean "eliminate cases"? Are you suggesting the
frequencies of copies of each experimenter that get different possible
results would have to be retroactively changed? I'm pretty sure that
wouldn't be necessary, at least it isn't in the toy model I suggested.
If on the other hand you just mean the laws are ensuring that you
don't get combinations that aren't allowed by the laws themselves,
again that just seems like the sort of thing you'd expect mathematical
laws of physics to do.
Exactly. But as I have pointed out, this only only achieved by the fact
that QM is intrinsically non-local.
As I said, I don't understand the details of the Mark Rubin papers,
but on p. 19-20 of the paper at http://arxiv.org/abs/quant-ph/0204024
he gives a more qualitative description of the model that the prior
parts of the paper have explained mathematically, and it at least
sounds as though it works in this way:
"Information encoded in an operator at one place at an earlier time is
transfered to operators at other places at later times in accordance
with a local differential equation. (In a relativistic theory
information is only transferred to later-time operators within the
future light cone of the earlier-time operator.) Operator- valued wave
packets corresponding to initially-separated particles may come into
contact and exchange information. At any time, at any location, the
value of the field operator is a weighted sum of products of
initial-time field operators, as in (154), (155) (of course
higher-order terms will in general be present). As one wave packet
passes by another it may acquire contributions to this weighted sum
which were “carried” to the interaction region by another wave packet
corresponding to another particle. (E.g., via the O(ε) change to
φ_V,[r]i due to the interaction term in eq. (154).) At later times
operators in this wave packet will retain these contributions, serving
as labels indicating that the encounter with the other wave packet
took place. Depending on the nature of the initial conditions and the
interaction, distant field operators at times subsequent to the
interaction may be entangled in such a way that the results of
measurements made upon them (when compared at still later times by
means of some other causal interaction) are correlated to a degree in
excess of that allowed by Bell’s theorem.5 As discussed in Ref. 22,
correlations in the Everett interpretation are correlations of
information exchanged in a causal manner between copies of measuring
instruments and/or the states of awareness of observers, so these
excess correlations in no way imply the presence of nonlocality."
Of course, what else? But the final claim is invalid: the EPR
correlations are not explained in such a way in the Everett (or any
other) interpretation. You either have non-locality or you have magic,
unless you go for 't Hooft's version of superdeterminism. You seem to be
plumping for magic.
Bruce
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