From newshub.ccs.yorku.ca!ists!helios.physics.utoronto.ca!news-server.ecf!utgpu!cs.utexas.edu!convex!darwin.sura.net!jvnc.net!netnews.upenn.edu!libra.wistar.upenn.edu Wed Feb 26 12:53:34 EST 1992
Article 3922 of comp.ai.philosophy:
Path: newshub.ccs.yorku.ca!ists!helios.physics.utoronto.ca!news-server.ecf!utgpu!cs.utexas.edu!convex!darwin.sura.net!jvnc.net!netnews.upenn.edu!libra.wistar.upenn.edu
>From: weemba@libra.wistar.upenn.edu (Matthew P Wiener)
Newsgroups: comp.ai.philosophy
Subject: Re: QM nonsense
Message-ID: <66994@netnews.upenn.edu>
Date: 21 Feb 92 18:40:03 GMT
References: <66422@netnews.upenn.edu> <427@tdatirv.UUCP> <66636@netnews.upenn.edu> <437@tdatirv.UUCP>
Sender: news@netnews.upenn.edu
Reply-To: weemba@libra.wistar.upenn.edu (Matthew P Wiener)
Organization: The Wistar Institute of Anatomy and Biology
Lines: 96
Nntp-Posting-Host: libra.wistar.upenn.edu
In-reply-to: sarima@tdatirv.UUCP (Stanley Friesen)

In article <437@tdatirv.UUCP>, sarima@tdatirv (Stanley Friesen) writes:
>In article <66636@netnews.upenn.edu> weemba@libra.wistar.upenn.edu (Matthew P Wiener) writes:
>|In article <427@tdatirv.UUCP>, sarima@tdatirv (Stanley Friesen) writes:
>|>At this point I say - positing a superposition of states serves no
>|>theoretical purpose, and is no longer required by any prediction of
>|>the theory, so throw it out as a needless complication.

>|And at this point others say that positing a wave function collapse before
>|the human observer serves no purpose either, and it is no longer required
>|by any prediction, etc.

>Except that this requires one *additional* assumption,

So you are admitting that it's a philosophical decision regarding the
experiment?  That's my basic point.  The various experiments that are
around cannot prove any interpretation, they can only make explicit what
is already know about QM weirdness.

>						        namely that the
>human mind has some mysterious, presumably non-physical, capability
>that induces decoherence (I like that term).   It is this additional
>assumption that makes it unacceptible by Occam's Razor.

I wouldn't say that's an assumption--it's an experimental observation!
We do observe a classical world.

The radical Copenhageners would phrase it that collapse isn't understood,
and neither is conscious observation, so lump them together and get on
with the physics.  In contrast, your ideal detector is simpler if you
do not tack on this mysterious wave function collapse ability.

>The two interpretations are *not* equal in 'complexity'.  The interpretation
>involving physically caused decoherence at least postulates the existance
>of a *general* mechanism based on physical processes.

To which the Copenhageners say "Occam! Occam!"

>						        The Copenhagen
>approach requires something akin to dualism.

Akin yes.  Meanwhile, we *know* there's much not understood about mind,
but why should a trivial detector be not understood?

>|And how indirect are you willing to go?  Do you have a theory for saying
>|which items collapse wave functions and which don't?

>I have an intuitive feel for it, but my physics is too undeveloped for
>me to have a well-defined theory.

You and everyone else!  That's part of the reason Copenhagen is still
popular.  Just where does the quantum turn into the classical?  There
are no clear borderlines.

And meanwhile, experiment has not told us.

>|>In short, as long as superpositons have observable consequences, I am forced
>|>to accept them, where they do not, I see no reason to believe they exist.

>|No, you choose to accept them, and from there you duck certain hard
>|questions.  There are numerous interpretations out there, and each one
>|has its packet of strangeness and difficulty.  They differ from each
>|other wherein these packets lie.  If you only ask one question, it's
>|easy to pick a winner.  But like I titled a previous posting, "Occam's
>|barber had many customers."

>I still find the addition of a dualistic assumption when it is not *required*
>by the observations to be unacceptable.

No problem.  You have much company--by choosing to find this assumption
the most bothersome.

>					  And as far as I can see the
>concept of physically produced decoherence does not have any strange pockets
>left.

It is still very very ad hoc.  The amount that it can explain is impressive,
but the amount that it does not explain is immense.  You also have to believe,
in the GM&H treatment, in a history-integral formulation that involves a heck
of a lot of handwaving and a generalization of many-worlds and Copenhagen.

The whole show is very strange.  It might also be right!

>       It only remains to experimentally investigate the necessary and
>sufficient conditions for decoherence.

My point is, this is a theoretical/philosophical issue.  Radical Copenhagen
will explain the experiments as well as radical Many Worlds as well as Path
Integrals as well as a dozen or so other interpretations.

>I do not really think I am ducking the question, I am only requiring
>observable evidence before I accept strange assumptions.

I don't think you understand the question, if you keep mixing philosophical
problems with the experimental problems.
-- 
-Matthew P Wiener (weemba@libra.wistar.upenn.edu)


