On 12/10/2012 10:01 PM, Jason Resch wrote:



On Mon, Dec 10, 2012 at 1:35 PM, meekerdb <meeke...@verizon.net <mailto: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
    <mailto: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. 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'.

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


    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.

Brent

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