Andrew Clough wrote:
<I'd also like to note (since that section was cut out) that I was using
communication with the past to *disprove* quantum entanglement.>
>> snip <<
<This does not prove an absolute frame of reference!>
It is possible for a theory to be non-local
and Lorentz invariant at the same time?
When Bohm's non-local approach
is applied to relativistic quantum theory
we find that this theory is not Lorentz-invariant.
Bell's theorem (plus experiments) established
that (realistic) interpretations of QM must be non-local.
There's not, as far as I know, an analogous
*theorem* which proves that (realistic) interpretations
of QM must also be non-Lorentz-invariant.
Anyway an ideal experiment [1,2], by Lucien Hardy,
with 2 interferometers, one electron, one positron,
suggests that the simultaneous measurement
on these particles implies a preferred reference
frame (but does not tell us which frame is).
Another ideal device [3], by Ian Percival, consisting
in a double Bell-type experiment, with moving apparatuses
and linked outcomes, also suggests the existence of
a preferred refernce frame.
Now if there is a preferred reference frame, as implied
by these gedanken experiments, causal paradoxes
(such as backward causation, sending information
backward in time) are blocked.
The possible candidate for such a preferred reference
frame is the cosmic frame (as Bohm used to call it) and
especially the one in which the cosmic background
radiation is isotropic.
Notice that Wheeler [4] considered the possibility that
entanglement might occur on cosmological scales.
[1] Lucien Hardy, Phys. Rev. Lett., (1992), vol. 68, n. 20,
pages 2981 - 2984
[2] Hardy's "theorem" or "paradox" or "experiment" is also
discussed at http://arxiv.org/abs/quant-ph?0104062
(with pictures)
[3] I.C. Percival, http://arxiv.org/abs/quant-ph?9811089
[4] J.A.Wheeler, Law without law, in "Quantum Theory
and Measurement", Wheeler and Zurek eds., Princeton
U.P., 1983.
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