Brent Meeker wrote:
>Bruno, I can't tell whether you're being playfully obtuse or merely
>poetic, but you're not being straightforward.
I'm really sorry. I send that mail too quickly. I regret and I
admit not having been straightforward. Note that James's question
was very difficult, but that is not an excuse.
I was neither clear nor very funny. OK.
>Of course you know what
>is meant by the 'physical world'. It is that complex that we infer from
>our perceptions to provide a comprehensible account of the relations
>among those perceptions.
In *that* very large sense I believe in the 'physical world', sure.
But why the adjective "physical"? Why on earth should the world
necessarily be physical, and what does that mean?
I agree that for most people, words like "physical", "natural" and
even "empirical" have some easy meaning.
My belief is that such an eazy meaning is illusory.
My whole work try to explain that. And then I try to explain where
the illusion comes from.
That 'complex we infer from our perception' is arithmetical truth or
mathematical truth (I am not sanguine about the arithmetical
restriction). Stories like what we are living, including our
perception and the laws we infer are partial aspects on arithmetical
truth seen from inside. and "seen from inside" can be defined in terme
of relative computations (at least with comp).
>If you wish to take a radically
>fundamentalist position, avoiding all inference, then you can only
>speak of "softness" not "softness of velvet" and you cannot presume
>that you "feel only the presence of persons...". You can only feel -
>to assign a source to that feeling is an inference just as is the
>physical world.
This shows how much I was unclear, because I have no problem at all
with inference. I have a problem only with the inference of
material stuff or substance.
>I think you have the direction of abstraction
>backwards.
Indeed. I agree, and that's what is really difficult to accept
in my work.
>Perceptions and feelings are the raw stuff of being.
Perhaps, perhaps not. With comp it is more easy to postulate that
there is no raw stuff at all, only arithmetical truth like
"the number x apply to the number y relatively to the number z
gives the number t. Such collection of truth contains all
truth on the behavior, belief, even knowledge (definissable
axiomatically) of all possible machines embedded in all possible
neighborhood. I don't believe there is stuff, that is why
I feel obliged to explain why machines believes in stuff, why it
is locally useful with respect to their most probable computational
history, etc.
I really think that if we are digital machines (= if we can survive
with a digital brain) then "the law of physics" can be derived
from "the law of psychology", which are themselves derivable from
computer science, through the discourse of the sound universal
machine. This is what I called the reversal between physics
and machine's psychology.
>Persons, velvet, and the physical world are abstracted from them.
>Information is, as you say, another level of abstraction away from the
>physical world - but in the direction away from raw experience.
Mmmh ...
For easyness I repeat James Higgo question:
>> In conversations with friends, I am often asked why the minimal
>> Kolmogorov complexity of Tegmark's schema has any relevance to the
>> physical world. Why should information theory tell us anything about
>> the 'real' world? What grounds do we have to believe that the stuff
>> of the 'physical' world is information?
If the word 'information' (which is a confusing word which has a
lot of meaning) is taken in the lay psychological sense (like in the
sentence "I know because I get the information", then my shortest
suggestion to James would be based on the idea of virtual reality.
BEGIN SHORT ANSWER 1
Reality is dream sharing, which is information sharing. That is why
when we look outside or inside close enough, information theory
shows its nose.
END SHORT ANSWER 1
James can then suggest the reading of Daniel Galouye's
SIMULACRON III, or the more recent PERMUTATION CITY by Greg Egan.
These novels illustrate very well the idea.
But I should without doubt make precise that people like David
Deutsch, Ekert, Landauer (and a lot more) would answer James
Higgo in another, quite opposite, way : they would answer that
information theory play a role in our study of nature because
we realise, through the discovery of quantum information science,
that information is physical.
I, personaly, don't believe that at all, I believe, on the
contrary, that physics is informatical, right at the start.
(Actually I argue that such reversal follows logically from
comp, that's the purpose of my thesis, cf my URL).
I will think for better 'short' answer.
Bruno
http://iridia.ulb.ac.be/~marchal
Received on Wed Feb 07 2001 - 06:26:26 PST