On Tue, Apr 19, 2022 at 5:19 PM Quentin Anciaux <allco...@gmail.com> wrote:

> Le mar. 19 avr. 2022 à 09:14, Bruce Kellett <bhkellet...@gmail.com> a
> écrit :
>> On Tue, Apr 19, 2022 at 4:52 PM Quentin Anciaux <allco...@gmail.com>
>> wrote:
>>> Le mar. 19 avr. 2022 à 03:20, Bruce Kellett <bhkellet...@gmail.com> a
>>> écrit :
>>>> On Tue, Apr 19, 2022 at 11:09 AM Brent Meeker <meekerbr...@gmail.com>
>>>> wrote:
>>>>> On 4/17/2022 1:45 PM, George Kahrimanis wrote:
>>>>> Just as in Schroedinger's famous example with the cat, you need a
>>>>> "box" and an observer outside, in order to make sense of the cat being in
>>>>> an entangled superposition. Instead of a superobserver, we can do with an
>>>>> impersonal quantum description (in any chosen frame of reference), if you
>>>>> prefer.
>>>>> The only purpose of the box in Schroedinger's thought experiment was
>>>>> to put off the observers perception.  Really the thought experiment is 
>>>>> over
>>>>> when the radioactive decay occurs.  That atom has transitioned to a
>>>>> different nuclear state which is entangled with and recorded in the
>>>>> environment.
>>>> Yes. Schrodinger had the cat in a box to emphasize the idea that the
>>>> cat was in a macro-superposition of alive/dead. This misled Wigner to the
>>>> extent that he thought the state collapsed only when the box was opened.
>>>> All of this was made redundant when it was realized that decoherence
>>>>  rendered the state definite almost instantaneously. Saibal makes the same
>>>> mistake when he claims that Alice, after her measurement, is still in a
>>>> superposition until Bob sees her result. The idea that the superposition
>>>> still exists since decoherence is only FAPP is something of a red herring
>>>> -- in MWI, Alice has branched according to her result into up and down
>>>> branches that no longer interfere. There is no macro-superposition.
>>>> Bruce
>>> It's because Saibal sees observers as "machine"... so until anything is
>>> recorded in the machine available memory... it's in a superposed state.
>> I think you are referring to consciousness in quantum computers where
>> there is no decoherence. The trouble with this idea is that without
>> decoherence, no permanent memories can be formed, so it is difficult to
>> know what "observe" means in that context. In any ordinary machine,
>> decoherence is everywhere, so no superposition ever endures. Observers
>> cannot be in superposed states (observation requires the formation of
>> records, and that in turn requires decoherence, which destroys
>> superpositions.) Saibal refers to observation as "an algorithm". But
>> without specifying what runs the algorithm, his claim is devoid of meaning.
>> Bruce
> No I'm referring to consciousness as a "program" that can run on a turing
> machine... the consciousness is well defined and finite at each steps and
> can be represented as a big integer... and until the information from the
> "outside" reach the memory of that program, it's unique... even if the
> experiments has already been done and splitted the environment, the actual
> consciousness split occurs once the memory of the "consciousness program"
> is modified... until it actually records that fact.

What use is that? You don't know that anything has happened until it has
decohered and is recorded. Being in a superposition is nothing special.
everything that can be represented as a vector (or ray) in Hilbert space is
in an infinite number of different superpositions all the time. There are
an infinite number of possible bases for the Hilbert space, and the state
is a superposition in all of these bases, except the one basis that is
stable against environmental decoherence.


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