Re: Quantum Probability and Decision Theory

From: Stephen Paul King <>
Date: Mon, 30 Dec 2002 11:03:26 -0500

Dear Bruno,


----- Original Message -----
From: "Marchal Bruno" <>
To: <>
Sent: Monday, December 30, 2002 8:26 AM
Subject: Re: Quantum Probability and Decision Theory

> Stephen Paul King wrote:
> > There do exist strong arguments that the "macroscopic state" of
> >is not completely classical and thus some degree of QM entanglement is
> >involved. But hand waving arguments aside, I would really like to
> >how you and Bruno (and others), given the proof and explanations
> >in these above mentioned papers and others, maintain the idea that "any
> >quantum computer or physical system can be simulated by a classical
> >computer."
> I agree with almost all the quotations you gave in your post
> But they are not relevant for our issue.


    When what is?

> Quantum computer can be emulated by classical computer (see below).


    Please point me to some paper, other than yours, that gives something
better than a hand-waving argument of this statement.

> Quantum computer does not violate Church thesis. The set of
> quantum computable functions is the same as the set of classically
> computable functions.


    This is one statement that I found:
"Church's thesis. All the models of computation yet developed, and all those
that may be developed in the future, are equivalent in power. We will not
ever find a more powerful model."

    Statements of this kind are found in religious dogma and are not
acceptable in mathematical and logical circles unless they have adjoining
caveats and attempted proofs. No where do I find this. It reminds me of
Kronecker's statement "God made the integers; all else is the work of man."

    I do not intend to be impolite here, Bruno, but, Please, give me some
reference that discusses how it is that "The set of
quantum computable functions is the same as the set of classically
computable functions."

    I can not see how this is possible given that (as Svozil et at state in )
"for quantum systems representable by Hilbert spaces of dimension higher
than two, there does not exist any such valuation s: LŪ {0,1} ... there
exist different quantum propositions which cannot be distinguished by any
classical truth assignment."

    If there does not exist a unique Boolean valuation for QM systems that
can be taken to exist a priori and given that UTMs, including UD, demand the
existence of such for their definition, how is it that you can continue to
make this statement?

> The difference are the following points 1) and 2):
> 1) A classical computer cannot emulate a quantum computer in "real time",
> nor 2) can a classical computer provide a pure 3-person emulation of
> some quantum *processes* like the generation of truly random
> numbers.
> But this is not relevant concerning our fundamental issue.
> Concerning 1) the only thing which matters is that the classical UD
> runs all programs including quantum one.


    Can UD run them all simultaneously or in some concurrent way that would
give us some way of finding solutions to the "foliation of space-like
hypersurfaces" problem of GR? Also, what are the "physical resource"
requirements of UD? What consitutes it's "memory" and its "read/write head"?

> THEN, by UDA reasoning, it is
> shown that "real time" is a 1-person (plural) emerging notion. Even
> if the UD need many googol-years to compute each "quantum step", from the
> inside 1-person point of view, that delays are not observable. CF the
> "invariance lemma" in UDA.


    I like this part of your thesis and my interest in it makes me ask these
very pointed questions. Additionally, I hope you would agree that there may
be an additional problem of how the "Principle of Least action" of physics
come about. Could it be considered, within your thesis, as just another
1-person aspect?

> Concerning 2): idem! We cannot generate truly random sequences, but we
> can easily (with the comp hyp!!!) generate histories in which
> most average observers will correctly believe in truly random sequences.


    Appeals to polls and beliefs should not be made. It would be more
helpfull if we considered such things as G. Chaitin's Omega when discussing
random sequences. Can UD compute Omega?

> It is enough for that purpose to iterate the Washington-Moscow
> self-duplication experiment. If you iterate this 64 times, most of
> the 1.85 10^19 version of you will conclude (correctly with comp) that
> they are unable to predict their next self-output (W or M) and that their
> histories, in this context are truly random.
> Now, the simple reason why the quantum is turing-emulable is that the
> solutions of Schroedinger or Dirac Wave Equation(s) are computable.


    Where is this explained? Please, some papers that you did not write...

> If you simulate such a wave you will realise that it simulates the
> many-world or many-dreams, even in such a way of making extravaguant
> histories much more rare than normal (lawfull) histories.


    It seems to more the case that it is the QM wave that simulated the UD
that, might, partially simulate the QM wave. ;-)

> This is not yet obvious with pure comp, where non quantum histories
> must yet be proved measure-negligeable (but see my thesis and posts to
> get a feeling why with comp it should be so, and why indeed it seems to
> be so).


    When is your thesis going to be available to those people, like myself,
who can not read French? Could you try a "machine" translation?

Kindest regards,

Received on Mon Dec 30 2002 - 11:05:15 PST

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