From newshub.ccs.yorku.ca!ists!torn.onet.on.ca!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!psinntp!scylla!daryl Tue Jun  9 10:07:42 EDT 1992
Article 6139 of comp.ai.philosophy:
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>From: daryl@oracorp.com (Daryl McCullough)
Newsgroups: comp.ai.philosophy
Subject: Re: Philosophical implications of  double slit ex
Message-ID: <1992Jun7.115623.29158@oracorp.com>
Date: 7 Jun 92 11:56:23 GMT
Organization: ORA Corporation
Lines: 51

jaeger@buphy.bu.edu (Gregg Jaeger) writes:

>>The reason why conscious beings always seem to collapse the wave
>>function is because of memory, which makes it impossible for two
>>observably different intermediate states to lead to the same final
>>state (where the state must include the state of the observer's memory,
>>as well as the state of the photographic plate).
>
>Would you be willing to generalize this explanation in order
>to cover all possible experiments or are you asserting it only 
>for the double-slit experiment?

I don't think that there is anything special about the double-slit
experiment, so, yes, I would be willing to generalize.

>In the later portion of this paragraph you seem to be close to a
>statement about wavepacket collapse in general. Your use of the word
>``seems'' in particular suggests that you believe that a physical
>mechanism for wavepacket collapse exists or that wavepacket collapse
>is unnecessary to account for observable phenomena.

I meant that wave function collapse is unnecessary to account for
observable phenomena.

>This latter portion I think could be written from the point of view
>of standard quantum theory as follows:
>
>The reason why one might think that wavepacket collapse has anything
>to do with the existence or nonexistence of interference is that it
>is easy to ignore the details of the description QM gives us about
>the two-slit experiment and to suppose that these can be overlooked
>by simple reference of the presence or nonpresence of consciousness.

If I understand correctly, then I agree. As far as I know, all
examples of loss of coherence are completely accounted for by the
Feynman rules: to calculate the amplitude for reaching a final state,
then add all amplitudes for paths leading to that final state. To
calculate the probability of a final state, square the amplitude. To
calculate the probability of an outcome, sum the probabilities of all
final states consistent with that outcome. (Remember, of course, two
final states are different if *anything* about them is different;
states can be microscopically different even if macroscopically
indistinguishable.)

Now, certainly some interpretations of the rules involve consciousness
collapsing the wave function, but the rules themselves do not need to
make any reference to such a process.

Daryl McCullough
ORA Corp.
Ithaca, NY


