On Tue, Dec 11, 2012 at 12:48 AM, meekerdb <meeke...@verizon.net> wrote:

>  On 12/10/2012 10:01 PM, Jason Resch wrote:
> On Mon, Dec 10, 2012 at 1:35 PM, meekerdb <meeke...@verizon.net> wrote:
>>   On 12/10/2012 10:16 AM, Jason Resch wrote:
>> On Mon, Dec 10, 2012 at 10:30 AM, meekerdb <meeke...@verizon.net> wrote:
>>>  On 12/10/2012 2:56 AM, Bruno Marchal wrote:
>>>  But why isn't "It's a probabilistic world and it obeys the Born rule."
>>> a good explanation.  I'm all for finding a better explanation, i.e. a
>>> deterministic one.  But simply postulating an ensemble of worlds to make
>>> the probabilities "deterministic" in arbitrary way doesn't strike me as any
>>> improvement.
>>>  It is, as it explains interference, without adding something not well
>>> defined (apparatus, observer) not obeying QM (like with the collapse needed
>>> to get one physical reality).
>>> That sounds like prejudice against probabilistic theories.  The
>>> interference is inherent in the complex Hilbert space states.  The
>>> interference happens in one world.  As Omnes says, you don't need
>>> 'collapse' you just need to accept that you have calculated probabilities.
>>> That's what probability means - some state is actualized and others aren't.
>>  How does Omnes explain the EPR experiment without collapse?  It seems
>> you need to give up not only determinism, but also locality.
>>  Also, what do you think Omnes would predict as the outcome for
>> Deutsch's proposed experiment:
>>   In Deutsch's thought experiment, an atom, which has a determinate spin
>> state in one axis, 'left' for example, is passed through a Stern-Gerlach
>> apparatus which has the possibility of measuring it in another axis, as
>> either spin 'up' or spin 'down' in this case. This means that the atom is
>> then in a superposition of 'up' and 'down' states from the perspective of
>> an observer who has not yet become entangled with it. This superposition
>> travels to the AI's artificial 'sense organ'. Here it is provided with two
>> options, it may be detected as either spin 'up' or spin 'down'. The AI's
>> conscious mind then records the result. The collapse approach predicts that
>> this will cause the atom to collapse into one determinate state, with
>> either a determinate 'up' or 'down' (but not 'left' or 'right') spin. The
>> Everett approach predicts that the mind will branch into two, one mind will
>> record up and one down (but neither will record 'left' or 'right').
>>  The whole process is then reversed so that the atom emerges from the
>> entrance to the Stern-Gerlach apparatus and the mind forgets which result
>> it recorded. This process does not erase any of the AI's other memories
>> however, including the memory that they did record the atom to be in a
>> definite state. If a 'left-right' detector was placed at the entrance of
>> the Stern-Gerlach apparatus then the collapse approach predicts that it
>> will be detected as being in either a 'left' or 'right' state with equal
>> probability.
>>  I think it is wrong in saying that the erasure of which-way information
>> (which I think is actually impossible for a consciousness, artificial or
>> otherwise) will leave the atom in an up/down state.
> Isn't that exactly what the quantum erasure experiment shows?
> Quantum erasure requires that the which-way information be eliminated from
> the world.  Once an AI consciousness gets the result I think that implies
> entanglement with the world and after that the result can't be quantum
> erased.

What theory of consciousness are you operating under?  CTM or something

> I know Deutsch supposes a quantum computer AI can 'know' there was
> which-way information even though the which-way information was quantum
> erased.  But I find that doubtful.  And even if it's true, the 'reversal'
> may bring the atom back to 'left'.

That is the proposed result that would prove MWI.  If the "left" state is
restored always then the universe never collapsed, it split a difference
was observed, and a record of observing that difference was stored, then
all information pertaining to the result is erased such that the two
universes recombine (the split was undone, even though it should have
collapsed because the difference was observed).

>  Why do you think it is impossible for a conscious process learn the
> result and then have that result erased as in the quantum eraser experiment?
> Because I think consciousness must be quasi-classical.  Consciousness
> needs stable memory and it needs to interact with its environment -
> together I think that implies it must be essentially classical as a
> computer.

In this case it has stable memory, and is able to interact with its
environment, but then all traces of its memory of the which-way result are
erased.  We operate with unstable memories and forget things, and yet are
still conscious.

> That's one of my reservations about Bruno's oft repeated assertion that he
> has proven that matter doesn't exist.

He says matter exists, but that it is not primitive.  It can be explained
in terms of something more fundamental.

>   When pressed he allows that it may exist, but only derivatively within
> the computations of the UD.  But it seems to me likely that it, or
> something very like it, must exist (derivatively of not) in order that
> consciousness exist; that 'matter' is necessary for consciousness of a
> human kind to exist.

I think it's appearance is probable for entities such as we who evolved.

>>  You keep asking me about 'collapse', but Copenhagen's physical collapse
>> is not the same as Omnes epistemic collapse.
> I am sorry.  I don't feel I have a good understanding of what the
> distinction is.
> Omnes looks at it as a mathematical operation used in predicting
> experimental results.  That means the 'collapse' is just a change in
> description, not a physical process.

If it's not a physical process and only a description of appearances, it
sounds more like MWI.


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