>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 look at the photographic plate. 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. 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,
>
>so you get no interference. In the many worlds model all the other worlds
>still exist in parallel and will converge and interfere with each other when
>the electrons hit the photographic film.
This should test the many-worlds hypothesis vs the Copenhagen interpretation
that it's a *concious* observer that collapses the wave function. However,
it does not test many-worlds against other theories in which someting other
than a concious observer collapses the wave function. In those cases whether
the plate shows interference will depend on whether the quantum observer
causes a wave function collapse.
I'll throw in my own personal (and unsubstantiated) hypothesis for wave
function collapse as an example. I believe that wave function collapse
occurs when the quantum wave function would create a paradox. Some
calculations for quantum behavior include considering particles travelling
backwards in time (Hawking's black hole radiation). With time travel,
paradoxes are easy to cook up, so this is plausible to me. As to why the
wave function collapses in a particular way, I have no idea.
Anyway, by this hypothesis, conciousness does not by definition require the
ability to collapse wave functions. Perhaps conciousness involves so much
feedback that a conciousness cannot observe without collapsing a waveform.
In this case the quantum conciousness would not be able to perform the
required action of observing and signing while remaining in superimposed
states. If it were capable, then after erasure the photon would remain
un"observed" and you would indeed still see an interference pattern. So in
this case at least my hypothesis produces the same prediction as many-worlds.
P.S. I'm sure somebody else has published on this hypothesis. I seem unable
to come up with genuinely new ideas, although I frequently develop the same
ideas as other people without seeing their work. Chalk it up to the theory
that memes are formed mostly by the chance interaction of other memes rather
than by directed search on the part of human minds.