Re: Particle position

[Ron Ebert <ebert@CITRUS.UCR.EDU>]

At 07:14 PM 5/11/99 -0600, Arnulfo Castellanos Moreno wrote:

> Of course there are open roads for open minds:
>
> Following theories based in contextual hidden variables you can go
> to the quantum phenomena with nonclassical eyes. An example can
> be find in: Santos E. Phys. Rev. A46, 1992, pag. 3646. It is false that
> these kind of approaches does not have new information. It is enough to
> read it. One can consider contextual variables in the theories.

Santos basically states that all Bell experiments to date (that is, 1992)
are invalid as means of disproving local hidden variable (LHV) theories
because they contain a number of assumptions that may not, in fact, be
valid. Well, maybe so, but IMHO this is akin to trying to save the ether by
trying to nitpick Michelson-Morley and other experiments that look for
ether for the assumptions used in them. There's nothing really wrong with
doing this, and in the end, if you conduct further experiments that look at
the assumptions used in earlier ones, your conclusions will be all the
stronger (assuming nothing untoward was found).

In the case of LHV models, this, in fact, is being done with experiments
already carried out or proposed which will address most if not all of
Santos' objections. See, for example, Gisin, Physical Review A, 1998 May,
V57, N5:3229-3232. There is a pre-print version on the web at
http://xxx.lanl.gov/format/quant-ph/9809025. Also look at:

P. Kwiat et al., Phys. Rev. A 49, 3209 (1994).
E.S. Fry, T. Walther, and S. Li, Phys. Rev. A 52, 4381 (1995).
E. Hagley et al., Phys. Rev. Lett. 79, 1 (1997).
Santos, Shimony, Phys. Rev. A (General Physics) Oct 84, vol. 30
(No.4):2128-31.

> The inexistence of noncontextual hidden variables was proved by
> Gleason(5) in 1957 and by Kochen and Specker(6) in 1967. But that
> contextual hidden variables are always possible was shown by
> Gudder(7) in 1970.

Your reference to Gudder has an error. It's page 431 not 618.

> A contextual theory is formulated with variables of the next form:
> A(lambda,mu) where lambda represents the properties of the particle
> and mu the properties of the context. In this way several approaches are
> possible if someone wants to maintain his open mind. But if someone
> does not want to do it, then he can take quantum mechanics at the present
> form, but this does not mean that any new approach must be considered
> unnecessary or a methaphysical point.

This is more like it. Gudder proposes a hidden variable theory where the
distribution for the values of an observable is dependent upon the type of
measurement used to find these values, contrary to what quantum theory
calls for. I looked for but could not find in the literature any follow up
to Gudder's idea, not even for someone to lay out why it might be invalid.
I'm all in favor of new HV theories *that can be tested*. I have a lot more
respect for Gudder than for Bohm and his non-falsifiable HV model. I hope
that someone sometime will look at Gudder's model and poke holes in
it/propose an experiment/run an experiment.


> (7) Gudder, S.P., J. Math. Phys., 45, p. 618 (1970).


Ron Ebert
ron.ebert@ucr.edu
%%%%%%%%%%%%%%%%%%%%%%%

The apparent willingness to dismiss a new idea simply because it
lacks supporting evidence can give the appearance of a closed mind.
The true test of a closed mind is the dismissal of a new idea that
is supported by a large body of evidence or the dismissal of the
evidence itself - Greg Crinklaw, Astro list