RE: delayed reply

From: Marchal <>
Date: Mon Mar 22 02:56:35 1999

>I think many philosophical constructions, and especially those of classical
>metaphysics like Descartes, Leibniz and so on, ARE marvelous from a
>theoretical point of view. What I said is that HISTORICALLY they were
>never used to found any practical physical theory, although they may have
>influenced our way of thinking. I didn't know Steiner's book, but you must
>admit yourself that it has been written 50 years after the mathematical
>developments of QM, which were first motivated by empirical facts (hydrogen
>spectrum, Davisson and Germer's experiment and so on..).


>Even Turing's
>works were motivated by the technical development of computers That's an
>epistemological parenthesis.

Mmh..., I am not sure, but I will not insist on that.

>The only efficient way to select "good"
>theories of reality (not mathematical ones) has always been the comparison
>with observations, not pure logics.

I agree. Even arithmetic need introspective experimental observations and cannot be deduced by pure logic. That is indeed why Arithmetical Truth can be considered as an (immaterial) competitor against the (admittedly natural) hypothesis of the existence of some kind of substancial "universe".

>I offer a $1000 prize (seriously) if you succeed in that [= Higgo's
> exercise] without adding a
>statement beginning like: "And let define a universe as...., a correlation
>as ... and a subjective feature as...."

Even if you offer me a $ googol (10 raised to the power 100) prize, I will not try any attempt if you make impossible for me to ask you to agree on some definitions. I do not, indeed, need to define "universe", but I do need agreement on what correlations are, and, more importantly I need you to accept to make some thougth experiment from which we will find some kind of operationnal agreement concerning the "subjective feature".

>But then you will prove only properties of your formal definitions of
>Universes, not of the real Universe!

Science never prove. All proof appearing in theoretical scientific discourse are relative to some sets of empirical confirmations. And no empirical confirmation prove anything.
But science, in its relative way, put light on apparent necessities and possibilities.

>You won't have proven that these
>definitions describe correctly our Universe. Which again cannot be proven,
>only verified by experiments. Back from ontology to epistemology.

"verified by experiment" can only make bigger some of your theoretical (introspectively sound) belief. To observe is not to proof, just to confirm.

>>Let me try to put things another way:
>>OBSERVATION gives Standart QM, which is [Schrodinger Eq + Collapse].
>>EVERETT Theory is given by an ontology obeying [Schrodinger Eq];
>>THEN Everett & Co. gives an phenomenological explanation why we (as
>>machines) will observe the Collapse (with the right probability).
>Bruno, I disagree with these statements.
>1) Observation doesn't give standard QM. It has never contradicted it up to
>now, which is different.

Indeed ! (by "A gives B", I was meaning "from A you can
reasonnably INFER B"). This is related to what I say before.

>2) Everett theory (which is in fact only standard QM free from the logical
>unconsistency of collapse) is not an ontology as well. The idea of a
>wavefunction of the Universe is not free from ambiguity, and cannot be
>considered as an ontology. In fact it is not so diffrent from Bohr's

I don't agree. I suggest you (re)read the Everett FAQ or the first chapter of Deutsch book (the fabric of reality). Most quantum many-worlders, including Everett, takes the Universal Wave as describing the intended (despite remaining ambiguities) objective reality. Everett is quite explicit when confronting the (subjective) memories of observer-automata with the objective frame given by the wave function().
Remember also how Bohr quickly discard Everett's idea.

>3) Everett does not explain why we "observe" something (consciously).

The power of Everett's work comes from the fact that he uses no more than the "ability to recover the memory of a sequence of experimental measurements" for his "theory of consciousness". And he explains why we (or any machines with memories) observe a collapse.
That is why Everett fan are sometime COMP fan, and reciprocally.
Unfortunately he invokes for no reason the "psycho-parallelism" (perhaps to help him in distinguishing realities for memories). And he fails to realise that his strategy on the quantum histories extends itself on the computationnal histories, where indeed a little more elaborate "theory of consciousness" is needed. (But here I propose memory + basic provability or self-reference logic ...).

>>Consciousness is never defined in any physical or logical theory.

Nor is Matter :-)


() I quote Everett (The theory of the universal wave function, in the book edited by DeWitt & Graham page 109):

"We have shown that our theory based on pure wave mechanics, which takes as the basic description of physical systems the state function --supposed to be an OBJECTIVE [Everett's emphasis] description (i.e., in one-one, rather than statistical, correspondence to the behavior of the system)-- can be put in satisfactory correspondence with experience. We saw that the probabilistic assertions of the usual interpretation of quantum mechanics can be DEDUCED [Everett's emphasis] from this theory, in a manner analogous to the methods of classical statistical mechanics, as SUBJECTIVE APPEARANCES [my emphasis] to observers -observers which were regarded simply as physical systems subject to the same type of description and laws as any other systems, and having no preferred positions."


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Received on Mon Mar 22 1999 - 02:56:35 PST

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