Organization: Penn State University
Date: Wed, 12 Aug 1992 12:39:57 EDT
From: <MRG3@psuvm.psu.edu>
Newsgroups: sci.physics
Subject: Re: unitarity red herring
 <mcirvin.713566546@husc8> <1992Aug11.220546.5574@sei.cmu.edu>
 <mcirvin.713580405@husc8>

(Firth writes)

>This seems to me to be the flaw in most criticisms of Mr Sarfatti's
>experiment: they assume that the wave functions are decoupled, or,
>alternatively, that a measurement of one observable cannot affect
>an observable of the "other" particle.  This is circular reasoning:
>it is precisely that assumption that leads to Bell's inequality.

Actually, many of us contend that his description of the dynamics
between state preparation (emission of that entangled state) before
(either) measurement occurs is what is in error.  The QM description
has three parts
1-state preparation, i.e. the initial conditions, intitial state
2-dynamics-governed by the system hamiltonian, which does not depend
   on one (nonlinear variants of QM aside).
3-measurement-outcomes for which you calculate the probabilites.

(Matt McIrvine says)

>Actually, most criticisms of Mr. Sarfatti's experiment (still
>gedanken at this point, so far as I know) have been more
>careful about language than I was, and they have nothing to
>do with the locality involved in hidden variables.  They just
>assume that the evolution of the system occurs according to the
>rules of quantum mechanics.  Most of them forgot to mention
>the fact that measurement is nonunitary in many interpretations
>of QM, a fact that Mr. Sarfatti tried to use to dispel the
>"unitarity red herring"; but his spin-flip isn't what
>happens in a measurement either.
>
>--
>Matt McIrvin, professional gradgrind, amateur Usenet drifter

The nonunitary effects of measurement, projection onto the subspace of
the Hilbert space corresponding to measurment outcome, is used to calculate
probabilities for later measurements, and have no relevance to the objections
to Sarfatti's scheme based on its flawed description of what happens
before any measurement occurs.  The infamous transition, which I won't repeat
here implies that the evolution is either nonunitary or nonlocal.

To give you an idea of where Sarfatti is coming from, I found this
exerpt in a footnote in his Physics Essays paper:
"The literature on no-EPR-faster-than-light-communication proofs is extensive
...(list of such).  Their key assumption, which I deny, is that a measurement
on one member of the quantum connected pair always involves an interaction
which does not affect the "far-lying system" and apparatus.  This implies that
the one-sided measurement interaction is an operator only of the Hilbert Space
of the measured system plus local apparatus.  This further implies that the
one-sided measurement process can be described by a unitary operator which is
an identity operator on the Hilbert Space of the other side.  My claim is that
the Feynman rules deny this for a clever enough experimental design."

This, and other comments he has made suggest to me that he does not believe
the various formulations of QM are equivalent.  He also seems unable to
recognize that dynamics and initial conditions are two independent
aspects of the problem.  Well, I could go on (and on....) but i gotta
stop wasting time on this. (yours, gentle reader, and mine)
-mike gallis