On 10/27/2022 3:01 PM, John Clark wrote:
On Thu, Oct 27, 2022 at 5:05 PM Brent Meeker <[email protected]>
wrote:
/> as pointed out by Carroll in his explication of the delayed
choice quantum experiment, "...make the measurement you program it
to produce a document saying it has knowledge of which slit the
electron went through..." this can't be a real measurement,
because that would imply a record of it. /
But there *WAS* a record of whichslit the electron went through when
the document was written, that is how the machine got the information
that enabled it to sayit knew which way the electron went. It was only
after that the information was erased.
/> If it done just by correlating with a quantum variable that can
be erased it's not a measurement. /
Then why did the computer that you programmed say a measurement had
been done? Any information can be stored quantum mechanicallyand if a
computer stores that information quantum mechanically, which
conventional computers do not do, then that information can be erased.
/> Deutsch's whole idea depends on it being conscious of this
measurement because that obfuscates what can and can't be erased. /
No. The only reason Deutschmentions consciousness is that some rival
theories to Many Worlds think consciousness has something to do with
the question at hand, but if you're like Deutsch and me and believe
consciousness is irrelevant when talking about the foundations of
quantum mechanics then forget about consciousness and think about the
computer as just a scientific instrument that works on quantum
mechanical principles.
/> It's trivial to hook up a machine that just prints out "I
measured it."/
Obviously, but do you really think that's what Deutschwas proposing,
do you really think he's that stupid?
No. I mention it to point out that the crux of the question is exactly
how this information can be both measured and erased and documented.
That this is not a trivial "Well I can remember seeing something but not
what I saw" hand waving problem. And I think that if you actually
devised a way to doing it in qubits it will turn out like Carroll's
explanation to be completely independent of whether MWI is right or not.
Brent
Instead you program the computer to perform the best measurement
possible, and if it is able to determine which slit the electron went
through the machine writes a document saying it knows which way the
electron went through, but of course it does not specify which slit
that was; and if for some reason it is unable to make the measurement
it writes a document saying it was unable to make that measurement.
Then after the electron passes through the slits but before it hits
the photographic plate the witch-way information is erased. So when
the photographic plate is developed and if you see interference bands
then you know there must be other worlds than this one, and if you
don't see interference bands then the Many Worlds idea is bullshit.
/> You forget things and so you could measure something and then
remember you measured it but forget the value, but you can't
quantum erase the value measured...it just got decohered./
Decoherence usually spreads with enormous speedbut if things are
arranged very carefully, if only one electron in the universe got
decohered, then it's possible the electron could become re-cohered
because in the Many Worlds theory it makes no sense to talk about two
identical universes, so if the witch-way information of that electron
has been erased then there's no longer any difference between the two
universes and they merge back together.
John K Clark See what's on my new list at Extropolis
<https://groups.google.com/g/extropolis>
u6g
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