On 28 Nov 2017, at 14:50, Jason Resch wrote:



On Tue, Nov 28, 2017 at 6:06 AM, Bruno Marchal <marc...@ulb.ac.be> wrote:

On 27 Nov 2017, at 04:04, Jason Resch wrote:


Richard Feynman in "The Character of Physical Law" Chapter 2 wrote:

"It always bothers me that according to the laws as we understand them today, it takes a computing machine an infinite number of logical operations to figure out what goes on in no matter how tiny a region of space, and no matter how tiny a region of time. How can all that be going on in that tiny space? Why should it take an infinite amount of logic to figure out what one tiny piece of space/ time is going to do?"

Does computationalism provide the answer to this question,

Yes.    :)



Very nice. It seems then Feynman's intuition was in the right place. The second half of the above quote was:

"So I have often made the hypothesis ultimately physics will not require a mathematical statement, that in the end the machinery will be revealed and the laws will turn out to be simple, like the checker board with all its apparent complexities. But this is just speculation."

So it looks like that simple machinery is the machinery of the universal machine and the simple laws are those of Peano (or Robinson?) Arithmetic.


Any first order specification of a universal (Church-Turing) machinery will do. But it seems to me that we should avoid using induction axioms for the ontology (as I could explain someday, I discovered this more recently). So it is Robinson Arithmetic, and it is better to avoid Peano (for the ontology). Then, the "observer" (which is also a believer, knower, ...) we can use PA (whose existence is a theorem in RA).

But we could use combinators, of Lamdda Expressions. In fact any inductive structure who terms admits laws making it into a universal machinery will do. Iuse the numbers only because we are all familiar with them.

I have recent reason to suspect that if we put the induction axioms in the ontology, we can no more hunt away the white rabbit. Unfortunately, to prove this is not easy.




in the sense that even the tiniest region of space is the result of an infinity of computations going through an observer's mind state as it observes the tiniest region of space?

That might be OK, if space was something entirely physical, which is suggested by the physics of the vacuum, or general relativity, but with Mechanism, spece and time might be less physical than here suggested. The reason is that it is not clear how "empty space" could make a computation different from another,

I think what I was thinking here were "closed loop feyman diagrams", where any possible diagram might be drawn in the tiniest area of space, so long as it is closed, e.g. fluctuations/particle creations are permitted so long as they all cancel out. So if space is physical, and enables any of these fluctuations to happen, then this noise can take any possible value from the observer's point of view (like the polarization of a photon).

That could make sense. But I am still not at ease with quantum field theory enough, notably on how to interpret the "virtual particles". I would treat them as superposition, but some remark by Brent sometimes ago made me doubt this. I am not enough competent on this to get my hand to it.





and so space could be only a marker differentiating some computations, like time seems to be in the indexical approach. All this would need big advance in the mathematics of the intelligible and sensible arithmetical matter. I expect space to be explained by quantum knot invariant algebra due to subtil relation between BDB and DBD logical operators (I mean []<>[] and <>[]<>). Kant might be right on this, apparently space and time are really in the "categorie de l'entendement", I don't know Kant in English sorry, but this means mainly that they belong to the mind).


Thanks I very much appreciate these additional insights. I do subscribe to the belief that time is an illusion created by the mind. I have a little more trouble seeing that when extended to spacetime as a whole. Though perhaps what's come closest to helping me see this picture is Amanda Gefter's excellent book "Trespassing on Einstein's Lawn"--I would recommend it to everyone on the Everything list. It takes the approach that only things that are invariant are real, and from there proceeds to deconstruct almost all of physics.

Thank you, it seems interesting, I might try to take a look (when time permits),

Bruno


Jason


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