From: paul@mtnmath.UUCP (Paul Budnik)
Newsgroups: sci.physics
Subject: Re: hidden variables
Date: 25 Jan 93 17:29:39 GMT
Organization: Mountain Math Software, P. O. Box 2124, Saratoga. CA 95070

In article <1993Jan25.053921.11702@cs.wayne.edu>, atems@igor.physics.wayne.edu (Dale Atems) writes:
> In article <515@mtnmath.UUCP> paul@mtnmath.UUCP (Paul Budnik) writes:
> >[...]
> >I am confused by your statement. Eberhard proved that QM makes
> >predictions that require nonlocal effects or influence.
>  
> No, he proved that some of the predictions of QM require that the
> outcome of a measurement must depend on a distant setting.

This sound like a distinction without a difference. In what sense can
an event depend on a distant setting without that setting influencing or 
affecting the event?

>  
> >The Relativistic
> >Schrodinger equation is local and Lorentz invariant. One cannot derive
> >such effects using that equation.
>  
> This argument looks like a rather clever sleight of hand to me. The
> last statement requires a proof. While it's certainly true that one
> cannot use that equation to obtain an instantaneous change in the wave
> function at a given location due to a change in a distant polarizer
> angle, it's not at all obvious to me that you need this in order to
> describe what is happening. Maybe I'm missing something.

You do need an instantaneous change in the wave function that is
influenced by a distant polarizer angle to get the predictions of QM.
You can prove this. In effect that is what Eberhard did. Eberhard proved
that the observed experimental results depend on the setting of a distant
polarizer. In QM predictions about this observation are completely
determined by the wave function. Thus the wavefunction itself must
be dependent on (or be a function of) the distant polarizer angle.

> I've already shown that the nonlocal dependence required by Eberhard's
> proof is implicitly contained in the rotational invariance of the
> singlet state.

This is false. Without talking about time delays you cannot prove anything
about locality. It is easy to construct a local hidden variables model
that reproduces the correlations as a function of the angle between polarizers
just as QM predicts, if you do not put any constraints on the time between
when the polarizer angle changes and this has an observable effect. All
you need to do is put a little observer at each polarizer who sends by radio
waves the angle of the polarizer to each of the two detectors. A little
gremlin at each of the detectors uses this information and a previous
agreement about whether one of the two photons will be detected
to decide if the other will also be detected. If you only discuss the
rotational invariance of the singlet state you cannot prove anything
about locality.

> Thus the singlet state vector already knows how it will
> be affected by any possible combination of polarizer angles. I believe
> the effect can be described entirely in terms of local interactions.
> See my next post.

It knows how it will be affected by any combination of angles but this
is of little use without knowing what those angles are. You do introduce
a nonlocal change in the wave function in your analysis. See the following
response to your post.

Paul Budnik