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Article 6233 of comp.ai.philosophy:
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>From: mcdermott-drew@CS.YALE.EDU (Drew McDermott)
Subject: Re: Quantum consciousness
Message-ID: <1992Jun12.200308.25704@cs.yale.edu>
Keywords: quantum mechanics, consciousness
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References: <1992Jun10.142117.25171@cs.yale.edu> <1992Jun10.173555.27484@cs.ucf.edu>
Date: Fri, 12 Jun 1992 20:03:08 GMT
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In article <1992Jun10.173555.27484@cs.ucf.edu>, clarke@acme.ucf.edu (Thomas 
Clarke) writes [in connection with the many-worlds interpretation of QM]:
|>  
|> Don't you find the split at time T at least a little strange, 
|> somewhat arbitrary and ad hoc?  Why does O split at time T?
|>  (at every time or at any time for that matter)

As Everett explains, in the many-worlds interpretation observation is 
just a special case of correlation, in which two systems formerly 
described by separate wave functions interact in such a way that only
one wave function will suffice to describe them.  (Or, to be more precise
(I hope) that their joint wave function is no longer describable as the 
Cartesian product of the wave functions for the two original systems.)
E.g., put an electron and a proton into a box (separately).  Eventually
you will find a hydrogen atom in the box.  The two particles have 
"observed" each other.  The location of the hydrogen atom is itself given
by a wave function, but the positions of the electron and proton are no longer
independent.  Their wave functions have "collapsed" in a sense, although 
each particle could still be anywhere.  

|> Many worlds is a consistent interpretation of quantum mechanics 
|> in that it produces exactly the same observations and predictions 
|> as the standard model (otherwise it would probably be wrong since it 
|> would violate some experiment), and because of that I still maintain
|> many worlds is isomorphic to the standard interpretation.  

I question whether there is a coherent standard model.  As I understand it,
the standard model asks us to take the notions of "macroscopic object"
and "measuring instrument" as given (or even take the notion of "conscious
observer" as given, God help us), and states the laws governing the
behavior of elementary particles in those terms.  Such a theory cannot
in principle explain how a universe containing no macroscopic objects
or conscious observers came to contain such things.  The many-worlds
interpretation works just fine.  

If you want to put this in terms of predictions, how about this: The 
standard interpretation predicts that if the universe had begun as a
gigantic wave function (which presumably it did), it never would have 
collapsed, because it never would have encountered a measuring device.  
This prediction has been refuted by observation.

Actually, I'm being sophistical.  The standard interpretation predicts 
exactly what the many-worlds interpretation predicts: that this gigantic
uncollapsed wave function will come to consist of an unimaginable number of 
projections of alternative worlds containing different ways the primordial
universe could have evolved.  What's striking about the many-world 
interpretation is that it simply takes QM at face value.  It seems as
if the hard part for opponents is to explain why it isn't obviously true.

					-- Drew McDermott


