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From: weemba@brahms.BERKELEY.EDU (Matthew P. Wiener)
Newsgroups: net.philosophy,net.physics
Subject: Re: Does the moon exist?
Message-ID: <12710@ucbvax.BERKELEY.EDU>
Date: Thu, 27-Mar-86 04:37:31 EST
Article-I.D.: ucbvax.12710
Posted: Thu Mar 27 04:37:31 1986
Date-Received: Fri, 28-Mar-86 07:39:14 EST
References: <12628@ucbvax.BERKELEY.EDU> <12629@ucbvax.BERKELEY.EDU>
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Reply-To: weemba@brahms.UUCP (Matthew P. Wiener)
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Xref: watmath net.philosophy:4721 net.physics:3992

In article <12629@ucbvax.BERKELEY.EDU> desj@brahms.UUCP (David desJardins) writes:
>In article <12628@ucbvax.BERKELEY.EDU>
>   weemba@brahms.BERKELEY.EDU (Matthew P. Wiener) writes:
>>This comes from a debate in net.philosophy about whether existence is
>>the same thing as following physical law.
>>
>>To make the debate a little more interesting, I shall pursue one standard
>>view of modern physics a la John Archibald Wheeler.  In particular, I shall
>>suggest that following physical law, as it is now understood, implies that
>>either physical things do not exist or that a non-physical thing does.
>>..........
>
>   Rhetorical Question #1:  Is the moon physical?  Obviously yes.  (If the
>moon is not physical then nothing is, and the word has no meaning!)
>
>   Rhetorical Question #2:  Does the moon exist?  Again, obviously yes.
>Einstein's question, while insightful, is obviously rhetorical.  Whatever
>the word "exists" means, we had better make sure that we include the moon.

Einstein's question was NOT rhetorical.  It obsessed him the last 25 years
of his life.  He believed in what he called 'objective reality', ie, that
phenemona exist and occur without requiring the complete description of
the observer.  This view isolated him from the physics community.  He really
wanted to know if physicists took the opposing view literally.  Hence the
"experiment" to detect if the moon exists.

>   Non-Rhetorical Question:  What is the moon?  That is, what is is that
>we are referring to when we say "the moon"?  My answer has to be that it
>is a quantum wavefunction (or a segment of one) in the enormous Hilbert
>space we call the universe.
>
>   So, I don't think I agree with your conclusion.  The moon is a physical
>thing.  It is also a quantum wavefunction in a Hilbert space.  I do not
>find these irreconcilable, as you seem to.

I do not find them irreconcilable either.  But as you and I have different
notions of what a 'physical thing' is apparently, it's hard to see where
this leaves us.

>   I now feel ready to answer Einstein's question with confidence.  The
>moon doesn't go away when I don't look at it.  But it *does* get sort of
>fuzzy!

Yes!

ucbvax!brahms!weemba	Matthew P Wiener/UCB Math Dept/Berkeley CA 94720