From: danforth@riacs.edu (Douglas G. Danforth)
Subject: Re: Simple observation about Quantum Kitty Cats
Organization: RIACS, NASA Ames Research Center
Date: Mon, 5 Oct 92 00:44:19 GMT

In <301@mtnmath.UUCP> paul@mtnmath.UUCP (Paul Budnik) writes:

>In article <1992Oct1.125305.13437@oracorp.com>, daryl@oracorp.com 
(Daryl McCullough) writes:
>> In article <297@mtnmath.UUCP>, paul@mtnmath.UUCP (Paul Budnik)
>> writes:

>> The EPR-like correlations are certainly strange, but as far as I know
>> there is no experimental evidence contradicting the predictions of QM.

>I never said there was. I only claim that the predictions are unlikely
>to be true and not justified by any reasonable theoretical argument.

>> It seems clear to me that the wave function is not a physical field,
>> in the sense of the classical electromagnetic field. The problem shows
>> up when you consider the quantum mechanics of more than one particle;
>> the wave function becomes a function of position in configuration
>> space, rather than space-time. That is, in general the wave function
>> is of the form Psi(r1,r2,...,rn,t), where rj is the position vector
>> for the jth particle. As far as I know, there is no way to interpret
>> such a thing as a field---what is its value at the North Pole, for
>> instance? There is no such thing as the value of the wave function
>> at a particular space-time point, so it doesn't make much sense to
>> talk about that value collapsing.

>I am surprised that someone has not raised this issue a lot sooner in this
>discussion. Ofcourse you are correct. A physical wave function cannot be
>the same thing as the multiparticle Psi of quantum mechanics. It is only
>the single particle wave function for which such an identity is possible.
>Let me first give an intuitive explanation of what I think may be going
>on and then talk about how it can be handled in the existing formalism.

[remainder of comments deleted]

I am also suprised that this issue has not been raised earlier.  Paul's
argument about discrete vs continuous structure may be correct, however,
I'd like to add that the joint detection of n particles is a special
case of evolution of whatever the underlying structure may be.  By
special case, I mean that one would expect that the structure would 
not always be visible, not always observable and that only under certain
states or structural form would it make itself known as what we call a
particle or the results of an experiement.  The restriction of the
predictions of the n particle wave funtion to the joint observation of
n particles is precisely that, a restriction.  There are many, many,
other states that can evolve from a fixed initial experimental state
that would be thrown out by an experimenter as in valid or pooly
performed.  The thrown out states are those where fewer than n particles
are detected, from 0 to n-1.  This restriction to n particles detected
biases the data and introduces a form of "nonlocality" a posterori
(after the fact).  It is this biased data for which many-particle
quantum mechanics makes predictions.

We need a theory that predicts all possible experimental outcomes
(within a class of outcomes).  Such a theory, I believe, will turn out
to be local.

Douglas Danforth
Newsgroups: sci.physics