Re: Quantum Probability and Decision Theory

From: Marchal Bruno <>
Date: Mon, 30 Dec 2002 14:26:47 +0100 (MET)

Stephen Paul King wrote:

> There do exist strong arguments that the "macroscopic state" of neurons
>is not completely classical and thus some degree of QM entanglement is
>involved. But hand waving arguments aside, I would really like to understand
>how you and Bruno (and others), given the proof and explanations contained
>in these above mentioned papers and others, maintain the idea that "any
>quantum computer or physical system can be simulated by a classical

I agree with almost all the quotations you gave in your post
But they are not relevant for our issue.
Quantum computer can be emulated by classical computer (see below).
Quantum computer does not violate Church thesis. The set of
quantum computable functions is the same as the set of classically
computable functions.

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

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. 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.
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.
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.
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.
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).

Received on Mon Dec 30 2002 - 08:29:19 PST

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