H. Kragh ("Dirac: a Scientific Biography", Cambridge U.P., 1990) reports
a 1927 discussion between Dirac, Heisenberg and Born, about what
actually gives rise to the so called "collapse" (reduction of waves packet).
Dirac said that it is 'Nature' that makes the choice (of measurement
outcome). Born agreed. Heisenberg however maintained that, behind
the collapse, and the choice of which 'branch' the wavefunction would
be followed, there was "the free-will of the human observer".
I don't think this does justice to Born's views.
He was not a realist about the wave function
nor about its collapse. His position was that
the classical world was logically prior and
necessary for shared knowledge to exist.
Without it there could be no measured
values and no records.
Brent, maybe so, but Born wrote the following:
"The question of whether the waves are something
"real" or a function to describe and predict
phenomena in a convenient way is a matter of
taste. I personally like to regard a probability
wave, even in 3N-dimensional space, as a real thing,
certainly as more than a tool for mathematical
calculations ... Quite generally, how could we
rely on probability predictions if by this notion
we do not refer to something real and objective?"
(Max Born, Dover publ., 1964, "Natural Philosophy
of Cause and Chance", p. 107)
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