[extropy-chat] Many worlds and Hugh Everett

[John K Clark]

"Dirk Bruere" <dirk at neopax.com> Wrote:

> As it stands the interpretation can only be verified subjectively, and
>only  if true.

In a  book called "The Ghost In The Atom" David 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 a 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 at att.net