On 28 Jan 2010, at 02:46, Jack Mallah wrote:

I'm replying to this bit seperately since Bruno touched on a different issue than the others have. My reply to the main "measure again '10" thread will follow under the original title.

--- On Wed, 1/27/10, Bruno Marchal <marc...@ulb.ac.be> wrote:
I would also not say yes to a computationalist doctor, because my consciousness will be related to the diameter of the simulated neurons, or to the redundancy of the gates, etc. (and this despite the behavior remains unaffected). This entails also the existence of zombie. If the neurons are very thin , my "absolute" measure can be made quasi null, despite my behavior remains again non affected.

This relates to what I call the 'problem of size', namely: Does the size of the components affect the measure? The answer is not obvious.

Does the size of the components affects the computation?

My belief is that, given that it is all made of quantum stuff, the size will not matter - because the set of quantum variables involved actually doesn't change if you leave some of them out of the computer - they are still parameters of the overall system.

I don't assume the quantum stuff. It is what I want to understand. I gave an argument showing that if we assume computationalism, then we have to derive physics from (classical) computer science if we want to note annihilate the chance to progress on the consciousness/reality riddle.

But there is an important and obvious way in which size does matter - the size of the amplitude of the wavefunction, the square of which is proportional to measure according to the Born Rule.

I would say that if we really had a classical world and made a computer out of "classical water" waves, the measure might be proportional to the square of the amplitude of those waves. I don't know - I have different proposals for how the actual Born Rule comes about, and depending on how it works, it could come out either way.

I don't think there is any experimental evidence that size matters. But some might disagree. If they do, there are a few points they could make:

- Maybe big brains have more measure. This could help explain why we are men and not mice.

- Maybe in the future, people will upload their brains into micro- electronic systems. If those have small measure, it could explain the "Doomsday argument" - if the future people have low measure, it makes sense that we are not in that era.

- Maybe neural pathways that recieve more reinforcement get bigger and give rise to more measure. This could result in increased effective probablility to observe more coincidences in your life than would be expected by chance. Now, coincidences often are noticed by us and we tend to think there are many. I think this has more to do with psychology than physics - but who knows?

You wrote convincing posts on the implementation problem. I thought, and still think, that you understood that there is no obvious way to attribute a computation to a physical process. With strict criteria we get nothing, with weak criteria even a rock thinks. But comp, well as I understand it, attributes consciousness to computations, in the digital sense made precise by mathematicians. In that case we get a "theory of mind", indeed, the theory of what the universal machines (computers, interpreters, ...) are able to prove, and bet, about themselves and anything else. We just don't try to ascribe consciousness to anything material or observable. It is a mathematical phenomenon which appears when a universal machine observes itself. It accelerates with two universal machines in front of each other, and admit innumerable n-couplings.

Digital Mechanism makes Kant right, I think, that time and space belongs to the category of mind, with mind being arithmetic as viewed from the average universal machine "inside". It is idealism, but it is realism too, with respect to the elementary aritmetical truth, including computer science and computer's computer science. And so, it is precise and testable, thanks to the hard work of Gödel, Löb and many others.

To understand this you have to be agnostic, not just about the Creator, but also about the Creation. I hope yo are not religious on materialism or physicalism.

Arithmetic, through comp, determines a (very vast and intricate) web of relative consistent (n-person) histories, and it is an open problem if that web coheres enough to determine a unique, in which sense?, "physical reality". It is probably simpler to (re)define physics as invariant for the universal computable base. Computer scientists say "machine independent". No doubt we share deep computations, which are made stable below our substitution level by multiplications on the reals, or some ring. Comp is Church thesis, mainly, and the idea that "we" are Turing emulable.

Bruno Marchal


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