Quantum Computers

From: John Clark (jonkc@worldnet.att.net)
Date: Tue Aug 17 1999 - 11:25:45 MDT


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In another book called "The Ghost In The Atom" Deutsch does give what
he considers a definitive test of the Many World Interpretation and
a Quantum Computer is part of it, but it must be intelligent.

In the Deutsch test a conscious quantum computer shoots electrons at a metal
plate that has 2 small slits in it. It does this one at a time. After leaving the plate
the electrons hit some photographic film, but do not look at the photograph until
later. The quantum mind has detectors near each slit so it knows which slit
the various electrons went through. The quantum mind now signs a document
saying that it has observed each and every electron and knows what slit each
electron went through. It is very important that the document does not say
which slit the electron went through, it only says that they went through
one slit only, and the mind has knowledge of which one. Now the mind uses
quantum erasure to completely destroy his memory of the experiment. The only
part remaining is the document. Now develop the photographic plate and look
at it. According to Deutsch if you see interference bands then the many world
interpretation is correct. If you do not see interference bands then there are
no worlds but this one and the conventional interpretation is correct.

Deutsch thinks an experiment like this will actually be performed in the
first half of the next century. The reason it's so difficult to test is not
many world's fault, the reason is that the conventional view says that
conscious observers obey different laws of physics, many worlds says they
do not so to test who's right we need a mind that uses quantum properties.

In the Copenhagen interpretation when the results of a measurement enters
the consciousness of an observer the wave function collapses,
in effect all the universes except one disappear without a trace so you get
no interference. In the many worlds model all the other worlds will converge
back into one universe when the electrons hit the photographic film
but their influence will still be felt, you'll see indications that the electron went
through slot A only and indications that it went through slot B only, and that's
what causes interference. Time will tell who's correct.

     John K Clark jonkc@att.net

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