[extropy-chat] AAAS conference on retrocausation

scerir scerir at libero.it
Fri Jun 23 21:35:57 UTC 2006

Damien Broderick [hi!] quoted:
The best evidence for reverse causation - perhaps
the only evidence, said Sheehan - comes from
parapsychology, which investigates phenomena not
explained by the known laws of science, such as
telepathy, clairvoyance and psychokinesis (the
alleged ability to move matter with the mind).

### There is an interesting short paper, online,

written by Olivier Costa de Beauregard, who was
a pupil of L. de Broglie, and a very good theorist.

In 1947 C.d.B. gave the first interpretation
of the EPR effect, in terms of retarded and
advanced actions between the two space-like
separated analyzers, via the source of correlated

As early as in 1983, he gave a CPT-invariant
formulation of the EPR setting that allows
a time-reversed EPR (also known as RPE, after

One might think that, in such a RPE effect a late
_entangling_ event (i.e., the detection of a photon
emitted by a couple of lasers, in such a way that
nobody knows which of the lasers emitted the photon)
really affects, backwards, the (supposed already happened)
history of two atoms scattered by those lasers (each atom
on the path of each laser).

One might also argue that this RPE does not time-reverse
the EPR setting because (in order to be sure that Bell's
inequality - which is timeless, of course - is violated,
and a real entanglement happened, ex post, in those two
atoms) some property of those two atoms must be measured
only _after_ the detection of the _entangling_ photon.

Hence, the entangling event still remains in _a_ past,
at least in practice. Damn Copenhagen!

Notice, however, that the late _entangling_ event (detection
of a photon) can lie in a region space-like separated from
the two atoms. Hence, saying that ... you can imagine the two
atoms begin to violate Bell's inequality only at the moment
the photon was detected in a space-like separated region ...
appears to be crazy, according to SR.

Hence, having once again this conspiracy between QM and SR,
one is allowed to think that:
1) there is no space-time around here, and one can see the
   EPR and the RPE effects dancing together in a Hilbert
   space (more formally, the space of C* algebras);
2) there is a space-time, and you can explain both EPR and
   RPE by means of retarded plus advanced actions or, in
   simpler words, following reversed time-like paths (Olivier
   Costa de Beauregard).

[As a side note Born derived his famous 'rule', in the second
1926 paper about the interpretation of psi, considering
advanced and retarded perturbations in the scattering
problem he was studying.]

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