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Article 6024 of comp.ai.philosophy:
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Subject: Re: Quantum mechanics (no AI here, sorry)
Message-ID: <1992Jun01.234940.40210@spss.com>
>From: markrose@spss.com (Mark Rosenfelder)
Date: Mon, 01 Jun 1992 23:49:40 GMT
References: <1992Jun1.201556.24184@news.media.mit.edu>
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In article <1992Jun1.201556.24184@news.media.mit.edu> nlc@media.mit.edu 
(Nick Cassimatis) writes:
>I've always been bothered by arguments using quantum mechanics.  One
>reason is all of those books claiming to explain Experience,
>Consciousness, Art and Everything else using Quantum Mechanics.  But a
>alot fruit brains don't falsify a theory.  The more principled reason:
>a scientific theory is not set in stone.  There is every reason to
>believe that it will be revised, extended or even thrown out.  

Don't get your hopes up.  After 70 years there are no known holes in QM--
it's always agreed with experiment.  Nor is there any guarantee
that if it *is* replaced, you'll like the replacement any better.  :)

>In particular, there are a few facets of arguments using QM that have
>always puzzled me.  As I have yet to take a course in QM (though I may
>in the Fall) perhaps someone can enlighten me: it seems that peaple
>like to revel in Heisenberg's Uncertainty Principle and see it as the
>downfall of Laplace.  But I see it this way.  That Principle is only a
>statement of our experimental impotence.  It suggests that it is
>impossible to know the state of the universe at a particular moment.
>Even if this is true, so what?  Laplace's statement is based on a
>counterfactual: "If I knew the state of the universe...."
>Heisenberg's principle only suggests that we can't know the state of
>the universe, it says nothing about what could be done *if* we did
>know the state of the universe.

It sounds like you're thinking there is a "real" state of the universe--
or, to put it into more concrete terms, an electron does have a definite
position and momentum-- only we can't find out what they are.  Heisenberg
actually goes further than this: there is no "real" state of the universe;
you can't find out the electron's definite position and momentum because
it doesn't have one.

Common sense rebels at this; but common sense needs to spend more time
thinking about waves.  Any wave can be built up out of superimposed simple
waveforms-- e.g. sine waves or impulse waves.  A particular wave might
be built up out of just 3 sine waves, in which case it will take a whole
bunch of impulse waves to synthesize it.  Or if it only takes a few impulse
waves, the analysis into sine waves will be very complex.  You can't have
a wave that's extremely simple in both sine-wave terms and impulse-wave
terms, because these are opposite types of waveforms.

This isn't just an analogy-- it's the reason behind the "uncertainty
principle."  Position and momentum are different aspects of the quantum
wavefunction of a particle; you can't get both at the same time for the
same reason you can't analyze a wave into simple superimpositions of
opposite waveforms.

Now, your idea that the universe does have "real states" even if we can't
(yet?) observe them is not new; such "hidden variable" theories can be
built which are compatible with quantum facts.  However, it's been
pretty well established that such theories can't explain the facts without
recourse to faster-than-light signalling.

For further reading, I'd recommend Richard Feynman's _QED_, Nick Herbert's
_Quantum Reality_, and J.C. Polkinghorne's _The Quantum World_.


