From: leao@buphy0.bu.edu (Joao Leao)
Newsgroups: sci.philosophy.tech
Subject: Re: Hidden Variables
Date: 17 Aug 92 15:39:29 GMT

In article <86331@netnews.upenn.edu>, weemba@sagi.wistar.upenn.edu (Matthew P Wiener) writes:
|> In article <1992Aug16.203826.10685@galois.mit.edu>, tycchow@riesz (Timothy Y. Chow) writes:
|> >1. How accurate is Peebles' claim?  To what extent can it be proved that
|> >nobody will ever devise a local hidden variables theory?
|> 
|> It can't be, as Pitowsky has devised such.  Unsurprisingly, it has certain
|> features that fit in the "cure is worse than the disease" category.  He
|> uses non-measurable sets and the continuum hypothesis to construct his
|> spin models, thereby evading one of the basic assumptions of the proof.
|> In short, quantum indeterminacy is a byproduct of our inability to ever
|> get a grasp on non-measurability, and that the EPR correlations are really
|> due to extended objects interacting locally.
|> 
|> (Note that "non-measurable" here is the Lebesgue notion, and it is not
|> related to the quantum notion of "measurement".)
|> 
Lebesgue notion of measure (I take it that is what you mean!). Pitowsky
"proof" has essentially no meaning as it he would be hard-pressed to
explain what locality means in a non-Lebesgue measurable space...

|> >2. Are there any plausible non-local hidden variables theories around?
|> 
|> Not really.  The people who peddle them are under the delusion that
|> determinism is so inherently overwhelmingly plausible that no one will
|> notice the tons of raw sewage rotting in the far corner.  It doesn't
|> work that way.
|>

There are nonetheless people who have worked with such theories as proposed
by Bohm, Vigier and DeBroglie. The problem is hardly the preservation of
determinism as you can easily produce a non-local, non-deterministic 
hidden-variable (complete) theory from any of the above formalisms.
The point is why prefer any of these to quantum mechanics which is so
much simpler? In any case none of those theories is invalidated by
existing theorems or experimental results...
 
|> >I frequently encounter technically naive philosophers who have a strong
|> >feeling that nature is fundamentally deterministic, and so I'm interested
|> >in seeing how strongly one can argue against hidden variable theories.
|> 
|> Such are not just technically naive.  They are also philosophically naive.
|> The job of philosophy is not to demonstrate right or wrong but validity
|> or invalidity.  It's not enough to have one particular strong feeling
|> about nature--you have to show how it fits in with everything else.
|> -- 
|> -Matthew P Wiener (weemba@sagi.wistar.upenn.edu)

The arguments by Bell and (recently) Greenberger,Horn and Zeilinger make it
very difficult if not impossible to argue for hidden variables. The last one
is particularly interesting because it contemplates cases of deterministic
predictions by h.v.theories which are invalidated by QM predictions. Unlike
the Bell/Wigner/CHSH cases these have not been subject to empirical test but
no one doubts what such tests would yield if they were ever carried out...

I agree that philosophy does not legislate right and wrong (not even in
ethics) but I don't think it legislates validity either (it is physics that
does, in this case). It is likely that some people will always prefer 
_complete_ theories to quantum mechanics, as a questionable aesthetical choice,
but they are allowed to do so by available empirical data. That fact that
most of us think they are wrong is also a question of aethetics, after all.


Joao Pedro Leao (Artificial Iconoclast and Director of Computer Resources
Artificial Physics Lab * Boston University - Physics Dept. Boston MA 02215)
 	leao@buphy.bu.edu | leao@buphyc.bitnet | BUPHYC::LEAO 
"Well I am sitting here in Tahiti/ I am laying in the sun and sipping a...
...chartreuse tropical drink!/ and I say: I know those Bermuda shorts!..."