Jeremy Butterfield
(1954-)
Jeremy Butterfield is a philosopher at the University of Cambridge, noted particularly for his work on philosophical aspects of quantum theory, relativity theory and classical mechanics.
He analyzed the Bell inequalities in the light of Hans Reichenbach's principle of the
common cause, and has argued that the violation of these inequalities implies causation between the space-like separated wings of a Bell experiment. He writes:
In his PCC, Reichenbach's idea was that (i) if events E and F are correlated according to some objective probability function... : while
(ii) there is no direct causal relation between E and F then E and F must be joint effects of a common cause.
Reichenbach took this to mean that there must be a third event C in the 'common past' that 'screens them off, in the sense that their correlations disappear.
"Stochastic Einstein Locality Revisited," The British Journal for the Philosophy of Science, Dec., 2007, Vol. 58, No. 4
(Dec., 2007), pp. 805-867
While this idea of "screening off" is not clear,
John Bell suggested that a region 3 in light cone 1 "
completely shields off from 1 the overlap of the backward light cones of 1 and 2."
See our explanation of the
perfectly correlated outcomes at 1 and 2 as a
common cause, plus a
constant of the motion, plus the
spherical symmetry of the two-particle wave function.
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