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From: dgary@ecsvax.UUCP
Newsgroups: net.physics
Subject: Re: quantum mechanics and all that
Message-ID: <1137@ecsvax.UUCP>
Date: Wed, 29-Jan-86 10:18:44 EST
Article-I.D.: ecsvax.1137
Posted: Wed Jan 29 10:18:44 1986
Date-Received: Sat, 1-Feb-86 01:23:03 EST
References: <10137@tardis.UUCP>
Reply-To: dgary@ecsvax.UUCP (D Gary Grady)
Distribution: net
Organization: Duke U Comp Ctr
Lines: 37
Keywords: Schroedinger's cat
Summary: Bohr's philosophical view

A bit of clarification on the Copenhagen interpretation of quantum
mechanics:  In the referenced article Thomas Breuel describes the famous
Schroedinger's cat gedanken experiment in which a cat in a box has its
fate determined by a radioactive decay (which QM makes
nondeterministic).  Thomas talks about the hidden-variable and
many-worlds views, and says also:

>Other people suggest that the cat isn't really dead until someone observed
>that it is dead, i.e. that the decision about its death isn't made until
>someone observes it....

Yes, some hold this view, but a large number consider the cat's death,
or even the decay itself, to be the "observation" that makes the wave
equation collapse.  Any irreversible quantum-mechanical event amounts
to an observation in this view.

I have it on good authority that this was Nils Bohr's own
interpretation of quantum theory:  I heard John Wheeler say this is
what Bohr told him.

>. . . This point has no relevance. A physical theory
>does not gain anything by assuming that the decision is made at the point
>of observation; in fact, it looses simplicity...

It's certainly true that we can do physics without really understanding
quantum mechanics on more fundamental level, but I don't think such
philosophizing is pointless.  The number of physicists who engage in it
would suggest otherwise.  It is entirely possible that speculations
along these lines will ultimately lead to a better understanding of the
universe (including ways of distinguishing among views by experiments we
haven't thought of yet).  Remember that Newton called physics
"experimental philosophy."
-- 
D Gary Grady
Duke U Comp Center, Durham, NC  27706
(919) 684-3695
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