On 12/12/2012 4:01 PM, Jason Resch wrote:
On Wed, Dec 12, 2012 at 5:15 PM, meekerdb <[email protected]
<mailto:[email protected]>> wrote:
On 12/12/2012 9:25 AM, John Clark wrote:
On Tue, Dec 11, 2012 meekerdb <[email protected]
<mailto:[email protected]>>
wrote:
On 12/11/2012 9:31 AM, Jason Resch wrote:
>>> Everett's QM is not a theory; it's just an interpretations.
>> Not quite. Deutsch's proposed experiment with reversible
computation and
an AI yields different results for the CI and MWI, thus they are
theories
which can be tested and differentiated.
> Except his proposed experiment relies on a hypothetical quantum
computer that
is conscious.
Yes but Deutsch argues, convincingly I thought, that the reason it's so
difficult
to test is not the Many World's theory'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 Deutsch's experiment to prove or disprove the existence of many worlds
other
than this one a conscious quantum computer shoots electrons at a metal
plate that
has 2 small slits in it. It does this one at a time. The quantum computer
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 electrons 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 the memory of what slits the
electrons went through. But all other memories and the document remains
undamaged.
But why should I think this is possible? I'd like to see the actual
mechanism or
Hamiltonian that allows this.
And then the electrons continue on their way and hit the photographic
plate. Now
develop the photographic plate and look at it, if you see interference
bands then
the many world interpretation is correct.
No, it only means the 'consciousness collapses the wave-function' theory is
incorrect. It doesn't follow that MWI is correct.
If observing a definite result doesn't collapse the wave function then what
does?
Creating a record of it.
I think the experiment is meant to show collapse does not happen. And if there is no
collapse then you have the MWI.
MWI has the same problem as decoherence theory (except it tries to ignore it): How or what
chooses the basis in which the reduced density matrix becomes approximately orthogonal and
what is the significance of it not being exact. Copenhagen said the choice is made by the
experimenter and apparently Deutsch agrees with this because he thinks it's significant
that his AI is conscious. Decoherence theory hopes to show it is some objective feature
of the experiment, e.g. the Schmidt decomposition and purification has been proposed
http://ipg.epfl.ch/lib/exe/fetch.php?media=en:courses:2009-2010:qit:lect5quantinfo0910.pdf
Neither has really said how to deal with the inexactness of orthogonality, but once you
assume you can ignore the off diagonal terms then QM just predicts probabilities, as Omnes
says.
Brent
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