On 14-12-2017 22:35, Bruce Kellett wrote:
On 15/12/2017 6:25 am, John Clark wrote:
On Wed, Dec 13, 2017 at 10:38 PM, <agrayson2...@gmail.com> wrote:
> I notice you don't gave a damn about having a non
falsifiable theory.
David Deutsch proposed a test of Many Worlds about 30 years ago in
his book "The Ghost In The Atom", but
it would be very difficult to perform. The reason it's so
difficult to test is not
the M any
World's
theory 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.
Quantum Computers have advanced enormously over the last 30
years
so I wouldn't be surprised if it or something very much like
it
is actually performed in the decade or two.
An intelligent quantum computer shoots
photons at a metal plate
one at a time
that has 2 small slits in
it, and then the photons hit a photographic plate.
Nobody looks at the photographic plate till the very end of
the experiment.
The quantum mind has detectors near each slit so it knows which
slit
the various electrons went through.
After each photon passes the slits but before they hit the
photographic plate the quantum mind signs a document
saying that it has observed each and every
photon and knows
which slit each
photon
went through. It is very important that the document does
not say
which slit
any
photon went through, it only says that they went through
one slit
and one slit only and the mind has knowledge of which one.
There is a signed document to this effect for every photon
it shot.
Now the mind uses
quantum erasure to completely destroy
its memory of
which slit any of the photons went through; t he only
part remaining is the document
which states that each photon went through one and only one slit
and the mind (at the time) knew which one. Now develop the
photographic plate and look at it.
I f 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
quantum interpretation is correct.
This works because 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 because information on which slit the various photons went
through was the only thing that made one universe different from
another, so when that was erased they became identical again and
merged, but their influence will still be felt, you'll see
indications that the photon went through slot A only and indications
it went through slot B only, and that's what causes interference.
I think this argument pre-dates the work by Zeh and Zurek developing
the idea of decoherence. Decoherence remove the oddities of Copenhagen
as presented above in that it is not consciousness that does the work,
but decoherence. Bohr was saying essentially the same thing (though he
didn't know the words) when he talked about the importance of the
whole experimental set up.
That aside, Deutsch's idea fails because he has not fully implemented
quantum erasure. If a record exists of the fact that a 'welcher weg'
measurement was made, entanglement of the rest of the world with the
result of that measurement is not erased by merely resetting the
memory of the mind or computer. So in the proposed experiment, the
interference pattern is absent, and it is not a proper 'delayed
choice' situation.
Deutsch has also given a rigorous variant of this that I summarized in
my paper. It is possible in theory to experimentally prove the existence
of other branches where a different measurement result was obtained.
It's only impossible FAPP.
Saibal
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