Re: All feedback appreciated - An introduction to Algebraic Physics

From: Bruno Marchal <>
Date: Thu, 8 May 2008 16:31:29 +0200

Le 08-mai-08, à 06:48, Russell Standish a écrit :

> On Wed, May 07, 2008 at 03:40:00PM +0200, Bruno Marchal wrote:
>> even the non computable reals. And, given that from a first person
>> point of view we cannot be aware of the infinitely many delays, we
>> have to take into account, to eliminate white rabbits (or to refute
>> comp) all the possible computations at once, including those
>> dovetailing on the reals or on any non enumerable structure. I have
>> discussed this with Schmidhuber on the list some time ago. The non
>> enumerability of the reals cannot prevent the UD to dovetail on all
>> the
>> reals. From a third person point of view, everything is and remains
>> enumerable, but from the first person point of view, the subjective
>> indeterminacy has as domain something vastly bigger.
> Actually, it just occurred to me that awareness of delays (step 5 of
> the UDA) is where you and Schmidhuber part company. His speed-prior
> discussion is all about assigning lower measure to computations that
> take longer (eg have delays).

Really? I think Schmidhuber's speed prior concerns intrinsic
computational speed (like when comparing different algorithm). If not,
nothing computational would remains in Schmidhuber's approach. Step 5
(or even 4) is where I part company with Nozick's closer continuer
theory of identity, at least if the "closer" relation is based on the a
priori physical.

Anyway, I have a problem with speed prior, due to a theorem of Blum
(similar to a theorem by Godel) which says that universal machine can
always been sped up for sufficiently great inputs.
Not that some relative speed cannot play some important role, but this
has to be justified, not invoked.
Then, I have a deeper problem with the use of prior in general. That
needs ASSA, and, also, it lead to the question "why such prior" ?
And then, as I have often argue, there is that lack of distinction
between 1-person views and 3-person views like if the mind-body problem
does not exist. Here already Everett and Tegmark are a bit more
cautious, imo. (QM forces us to be cautious there, comp too, but it is
less evident apparently).

> Going back to the ASSA vs RSSA divide, Schmidhuber's picture requires
> the ASSA to work.

That is much more probable, yes, I think so too.



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Received on Thu May 08 2008 - 10:34:12 PDT

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