On 4/26/2018 5:55 PM, Bruce Kellett wrote:
From: *Brent Meeker* <meeke...@verizon.net>
On 4/26/2018 3:41 PM, Bruce Kellett wrote:
From: *John Clark* <johnkcl...@gmail.com <mailto:johnkcl...@gmail.com>>
On Thu, Apr 26, 2018 at 2:02 PM, <agrayson2...@gmail.com> wrote:
>
/ How many times must I remind you that Feynman explained that
very clearly.
/
42.
>
/Please repeat it. AG/
I originally sent this on December 14 2017:
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 Many
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; the 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. 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 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.
Quantum erasure involves more than just forgetting what happened.
What about Zurek's "many records in the environment". If you know
what happened, many traces of that result remain -- even if your
memory is erased. Deutsch on the wrong track, yet again!
Deutsch knows the difference, and he specifies quantum erasure, which
implies that the detection of welcher weg is never classical, i.e.
it is not decohered into the environment since if it were it could
not be quantum erased. Which is the point of my remark that maybe
all that would be proved is that quantum "detection" can't be
conscious. I'm pretty sure consciousness is a purely classical
phenomenon. So Deutsch's scheme to detecting welcher-weg but erasing
the knowledge may retain the interference pattern but just prove that
quantum knowledge is not conscious...something Borh might well say.
My point was that if there is a record that a measurement was made,
something irreversible has been extracted from the experiment. If the
QC is "conscious", then it has to interact with something to make this
irreversible record, so its quantum state is irreversibly changed. But
you are probably right: if there is no decoherence, then there is no
consciousness, since consciousness involves irreversible memory.
There are experiments already performed in which the welcher weg is
available but is erased, even spacelike relative to detection
https://arxiv.org/pdf/1206.4348.pdf
(I wonder if the French appreciated the labeling of their apparatus
BS-in and BS-out?)
Brent
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