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Article 6072 of comp.ai.philosophy:
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>From: holmes@opal.idbsu.edu (Randall Holmes)
Newsgroups: comp.ai.philosophy
Subject: Re: Quantum mechanics (no AI here, sorry)
Message-ID: <1992Jun3.225545.27925@guinness.idbsu.edu>
Date: 3 Jun 92 22:55:45 GMT
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In article <1992Jun03.203556.4561@spss.com> markrose@spss.com (Mark Rosenfelder) writes:
>In article <1992Jun2.161131.11780@guinness.idbsu.edu> holmes@opal.idbsu.edu 
>(Randall Holmes) writes:
>>If you think that the waves are real physical phenomena, then FTL
>>signalling is involved.  I think it is quite reasonable to suppose
>>that the universe has "real states"; the particle side of the
>>particle-wave duality is real; the wave side encodes restrictions on
>>what information we can have about the real situation.  There is no
>>reason why we cannot know that there are correlations between the
>>facts about two events which have a space-like separation, while we do
>>not know the actual facts; once we acquire further information about
>>one of these events, we immediately gain information about the other,
>>but there is no superluminal communication involved (the correlations
>>between the two facts derive from their common relationship with a
>>third event which has time-like separation from each of them!).  The
>>illusion of superluminal communication comes in when you suppose (and
>>I believe this is built into the axioms of the arguments against
>>hidden variables) that the waves are physical phenomena (and so behave
>>"locally").  
>
>I'm not sure I understand you, but I suspect you're wrong.  It's not just
>a matter of observing a correlation across a huge distance.  It's that
>you and another observer do something (twist a calcite crystal) and
>immediately, before any signal could move from one to the other, the
>correlation rate changes, in a way that can't be explained by local
>properties of the particles.  There's something non-local going on here.
>I don't see what difference it makes if you call it "phyical" or not.

It's local properties of the _waves_ that are involved.  Such an
experiment is carried out by setting up a state in two widely
separated locations which depends on an unobserved factor in a single
earlier event.  One then makes observations at the widely separated
points, and, lo, they agree with one another.  These results make
perfect sense (require no explanation at all, in fact) on a hidden
variables interpretation, i.e., on the interpretation that there was a
real underlying value to the unobserved factor in the earlier event
which we did not in fact observe (we couldn't observe it and do the
experiment, in fact).  The "non-locality" has to do (on my
interpretation) with the fact that getting extra information about
event A may immediately give me extra information about event B even
if A and B have space-like separation (suppose that event A and event
B are individuals listening to television broadcast years earlier from
Earth, at the same distance from the Solar System in opposite
directions in the conventional frame of reference of the Solar System,
and the information that I have acquired is a copy of the TV schedule;
I then know that if A watched "I Love Lucy" at a certain time, so did
B).  The extra factor in the QM experiments is that the information
involved is information which we are not "allowed" to have when the
experiment is first performed (there is no contemporary TV schedule to
be had); but the actual situation is one in which it is perfectly easy
to understand why the same thing will happen at the two widely
separated points, for essentially the reason described.  Suppose that
I do not have access to contemporary TV schedules; I can still be
certain that when I find out what was being watched at event A, I will
discover that the same program was watched at event B.





-- 
The opinions expressed		|     --Sincerely,
above are not the "official"	|     M. Randall Holmes
opinions of any person		|     Math. Dept., Boise State Univ.
or institution.			|     holmes@opal.idbsu.edu


