re: delayed reply

From: Gilles HENRI <>
Date: Wed, 10 Mar 1999 14:19:20 +0100

>Gilles wrote:
>>I may be wrong, but it seems to me that the notions of computer, program,
>>UD ans so on... require the notion of (time ) ordering. A Turing machine is
>>decribed as a sequence of states, not a set of states. But if time (as I
>>think too) is an illusion, why invoke a computation instead of some static
>>state? Then the set of all possible finite computations is N.
>>So you are basically saying: the Universe is N. But why not R, P(R) or any
>>more complicated set?
>I am not really saying "the Universe is N". I am saying (loosely
>If I am N then I will see R P(R) and a lot of complicated set, including
>a lot of universes and minds.

Maybe we have to better define the word "Universe", like in MWI. I suppose
that you call "universe" a observable macroscopic universe? If "Universe"
means the globality of all things that exist , it really includes a lot of
universes. So I think you are really defending the thesis that the Universe
is N.

I still have difficulties in accepting the idea that the reality "is" a
mathematical abstraction. The mathematics as we know them are mental
concepts than can be applied to modelize *approximately* what we observe
from the world. There is no example so far of a really "exact" theory, free
from any unconsistency and unaccuracy. Modern epistemology is seeing the
evolution of science as an always improving approximation of reality. So
you can as well defend the idea that mathematics will *never* give a
complete description of reality.

>> But Descartes (and his
>>predecessors) failed to discover most of the physical laws. Only Galileo
>>and Newton, by trying to explain experimental facts with laws, did really
>>found modern Science.
>Gosh!... I am afraid only a french can be so unfair to Descartes !
>What about the optic laws, his pionnering work on dreams and
>neurophysiology, etc. Descartes also emphasized the important role of
>personal conviction in both science and philosophy ...
>Without Descartes'arithmetization of geometry, neither Newton, nor
>Leibnitz would have invented calculus, etc.

I agree that it may be surprising that a French prefers the anglo-saxon
school to the French one! I think we have to distinguish between
mathematical theories, which do not require any comparison with experiment
to be proven, and physical ones, which do; I recognize that Descartes was a
great mathematician, and a good philosoph. But his contribution to physics
was not so great. Excepted the laws of refraction (which BTW he did not
justified rigorously), many of his ideas were not correct and had a
negative influence on the French scientists, who lasted to admit Newton's
ideas. 300 years later, the same happened with de Broglie...

>>It is not surprising that the people of the last XX century imagine the
>>world based on a computation, just like Greeks have imagined it as a
>>combination of four elements, or theologist have imagined it as driven by
>>God (it confirms that consciouness can only produce ideas from the
>>interaction with an outer world!)
>... unless you find God in yourself ! (Take this as a pun).
>But honestly I think that in the XX century there has been Church,
>Turing, Post, Godel, and Kleene, which lead to theoretical computer

I agree, but all these works were done to deal with computers, or with
formal logics, not with physical reality! be cautious not to mix different
fields and problems. The physics of XX century has not been built by these
great researchers, but by other great researchers like Einstein, Bohr,
Dirac, Schroedinger and so on. BTW they also contributed to the emergence
of new mathematical problems, but they were not pure mathematicians. (some
extraordinary workers like Kolmogorov brought decisive contributions in
both types of field, but in separate works).

I don't want you to mistake what I am saying. I am not saying that doing
physics is better than doing mathematics or computer science. i am just
saying that each field has its own domain of relevance ; although at some
precise interfaces, they can mutually enrich, one should be cautious in
applying them to domains for which they were not built.

>To derive explicitely laws of nature, there is a difficulty (both my
>director and Jacques Baihache have seen rather clearly) which is that I
>cannot draw a clear line between the necessary and the contingent laws :
>comp makes necessary to deduce (by pure thinking) only the necessary part
>of physics.

but you have to do that before convincing a physicist!.

>Have you follow the PE-omega experience ?

I missed that, could you explain it ? (I'm afraid it is not an experiment
in my sense!)

 If yes you should understand
>how comp makes it possible to predict indeterminisme, non-locality, and
>even some kind of quantum logic. Obviously physicist have discovered all
>that before computer scientist.`

What I think is that only the methods of physics could discover all that. I
don't think you can deduce that from N (see below).

 But computer science is still very young,
>and the idea that computer science can be "the" fundamental science is
>still "in-birth" (to say the least).

Let assume that theoretical computer science would have been developped
well before the technical feasibility of computers and the development of
modern physics. (It is possible in principle although mankind use to
develop only what is immediately useful...). With the idea that it is "the"
fundamental science, some people would have tried to apply it to try to
imaginate the most fundamental laws of physics, for which no experimental
data would have been available. Most probably, they would have arrived to
some atomic theory (because of the discreteness of computations) but also
most probably seeing the atoms like classical particles, like Democrite,
Epicure and Lucrece. Schmidhuber's programms, for example, could most
simply interpreted like the generation of classical worlds where "1" means
the presence of a classical particle and 0 an absence. There is nothing
wrong logically...just that you cannot make good physical laws with this


Received on Wed Mar 10 1999 - 05:31:01 PST

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