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From: rimey@ernie.BERKELEY.EDU (Ken &)
Newsgroups: net.physics
Subject: Re: Blimey, Rimey!
Message-ID: <11396@ucbvax.BERKELEY.EDU>
Date: Mon, 13-Jan-86 01:03:01 EST
Article-I.D.: ucbvax.11396
Posted: Mon Jan 13 01:03:01 1986
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Reply-To: rimey@ernie.UUCP (Ken Rimey)
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> Many moons ago, Ken Rimey posted an explanation/endorsement of the Many
> Worlds interpretation of QM.  I tried to mail to him, but no luck.  I
> noticed he's still around today, so here's my reply:
> 
> >You may have noticed that, in describing a theory in which the
> >universe is deterministic and measurement is not a fundamental
> >idea, I sure refer to measurement and probability a lot.  The
> >point is that these ideas are involved only in the interpretation
> >of the mathematical object that represents the state of the universe.
> >They don't clutter up the theory of how to calculate that object.
> >In particular, in the Many-Worlds view, wave functions don't "collapse".
> 
> Then what do measurements measure, in the Many-Worlds view?  Are "position"
> and "momentum" fictions?

Nothing different.  See the following quote.

> >Many-Worlds is indistinguishable experimentally from the more popular
> >variant of quantum mechanics that talks about wave functions
> >collapsing.  Then why is Many-Worlds interesting?  Indeed, Many-Worlds
> >is less a theory than an argument that some of the conventional
> >postulates of quantum mechanics are not fundamental. 
> 
> What do you mean, "some of the ... not fundamental".  And why is it
> important to argue that point?

What I mean is that it is unnecessary to postulate that wave functions
collapse during measurements.  Measurements are ordinary physical
interactions of matter with matter, and are adequately described by
ordinary equations of motion.

The reason to argue this point is to clarify that quantum mechanics
does NOT indicate that "observers" play a special role in the laws
governing the universe.

> >  Many working
> >physicists will, if you ask them, express doubt as to whether quantum
> >mechanics is really applicable to cats and such. 
> 
> And one interpretation of QM has it that it doesn't, because macroscopic
> objects like cats and such involve entropy (i.e. when the cat dies, entropy
> is increased, thus an irreversible process has taken place).

That is not an interpretation of QM.  It is simply wrong.

> On the "incompleteness" charge -- I assume you refer to the EPR thought-
> experiment -- how does the Many Worlds view answer the misgivings of
> EP&R?  How about the Bell theorem (does that pose any problem for the
> Many Worlds view)?
> 
> >					Ken Rimey
> >					rimey@dali.berkeley.edu
> 
> --Paul V Torek, umcp-cs!flink

No, the analysis of these thought experiments is independent of whether
you use the Many-Worlds viewpoint or not.

					Ken Rimey