Re: A nerw idea to play with

From: Gilles HENRI <>
Date: Mon, 6 Sep 1999 19:28:35 +0100

>> Gilles Henri wrote:
>>For me digital systems are systems whose some characteristics (description
>>and evolution of their "state") are EXACTLY equivalent to a TM. All our
>>computers are obviously of this type. All systems that are not known to be
>>digital must be considered as analogical (in fact they are all analogical
>>at another level of description). The burden of proof is for the
>>demonstration of "digital character", the default value being analogicalness.
>Do you think that a distance of 10^-500 has a accepted meaning for any
>physicist. Some physicist and mathematician believe that "analogical"
>system are "idealisations". At least with the "digital" there is Church
>Thesis which makes things clearer.
>>I do not know any description of our brain that is obviously exactly
>>equivalent to some TM. I would be very happy if someone in this group
>>could give me one.
>Any reasonable quantized version of Schroedinger equation. Nobody has ever
>proved the necessity of non-computable real numbers there. Only Penrose
>seems to search non-computability there, for rather obscur reasons.

One reason may be that we don't know the ultimate TOE, even in the
continuous form. The problem is not the use of discrete variables and how
accurately they can reproduce continuous ones. It is first that we don't
have any exact theory of the world. Schroedinger equation does not describe
properly relativistic QM or quantum gravity, and no one has succeeded in
finding a theory that answers anything. If you imagine a thought experiment
capable of simulating the quantum state of a brain (which requires indeed a
huge computer!), you can as well imagine an experiment testing quantum
gravity and interfaced with a brain - and no known theory could compute the
result. You MAY postulate that this computation exists, and that it is of
discrete nature, but this is a postulate.

I know that you present comp as a working hypothesis- I just insist that
comp is indeed the very strong hypothesis that there is a computable TOE.
I agree that with this hypothesis any system is digital (equivalent to the
computation of its state). In this case the separation analogical/digital
is useless. But there is another problem. Indeed I should have added a word
to my definition:

>>For me digital systems are systems whose some OBSERVABLE characteristics
>>(description and evolution of their "state") are EXACTLY equivalent to a TM.

Recalling that the quantum state of a single particle is not observable ( a
fact that seems to have been neglected by some computer scientists...) ,
unlike for example the magnetic moment of a computer memory cell, I
maintain that there is an objective distinction between digital systems and
analogical ones, and that the brain is not obviously digital : the clearest
difference between an analogical system and its digitized computation is
that the relevant information (quantum state) is fundamentally hidden in
the first case, but is known in the second one. This is as fundamental
physically as Church thesis for computability!
I see no reason why this fundamental physical difference would not have any
influence on the existence of consciousness. In fact all proposed
"simulated brains", Chinese room, Mauldlin experiment and so on imply the
use of classical systems whose state IS measurable - i.e. are digital
following the definition I propose. It may be why (as we tend to think
intuitively) they can't be able to think. Only the duplication of quantum
state would then be able to duplicate a consciousness....

Received on Mon Sep 06 1999 - 12:14:50 PDT

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