On Sun, Apr 17, 2016 at 7:34 PM, Bruce Kellett <bhkell...@optusnet.com.au>
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.


>
>> 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 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?

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. 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."

Jesse

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