# Re: The probability problem in Everettian quantum mechanics

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On 15 Oct 2013, at 19:39, meekerdb wrote:```
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```On 10/15/2013 7:49 AM, Bruno Marchal wrote:
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On 15 Oct 2013, at 12:45, Richard Ruquist wrote:

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Bruno: On the contrary: I assume only that my brain (or generalized brain) is computable, then I show that basically all the rest is not. In everything, or just in arithmetic, the computable is rare and exceptional.
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Richard: Wow. This contradicts everything I have ever though Bruno was claiming. How does anything exist if it is not computed by "the" or "a" machine?
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We assume the arithmetical truth. In particular we assume that all closed formula written in the language of arithmetic (and thus using logical symbol + the symbol 0, s (+1), + and *) are all either true or false, independently of us.
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From this we cannot prove that matter exists, or not, but we can prove that the average universal numbers will (correctly) believe in matter (but it will not know that it is correct).
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That's not at all clear to me. A universal number encodes proofs - is that what you mean by it believes something?
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Yes. (I am thinking about the Löbian universal numbers).

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```But how is this something identified at 'matter'?
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It should follow from the step seven.

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So, if you have no problem in believing propositions like "there is no biggest prime number" are true independently of me and you, and the universe, then you can understand that the proposition asserting the existence of (infinitely many) computations in which you believe reading my current post, is also true independently of us.
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The appearance of matter emerges from the FPI that the machines cannot avoid in the arithmetical truth.
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Arithmetical truth escapes largely the computable arithmetical truth (by Gödel).
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```And I thought the generalized brain did the computations,
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Only the computations associated to your mind.

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not that it was only computed. How does Bruno show that "all the rest" which presumably includes energy and matter is not computed. Bruno is constantly confusing me.
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I guess you missed the step seven of the UDA, and are perhaps not aware that arithmetical truth is incredibly big, *much* bigger than what any computer can generate or compute.
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Then my, or your, mind is associated to *all* computations going through your actual state of mind,
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That sounds like an uncomputable totality.
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No, by virtue of the closure of the set of partial (includes the total functions) computable functions for diagonalization, or equivalently, by the existence of universal machines/numbers, that totality is computable/enumerable, and that is why we do have a UD. What happens is that most interesting subset will be uncomputable, so that the FPI entails a priori the non computability of *some* physical things (which can be only the apparent collapse of the wave, but it could be more than that too: open problem).
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Bruno

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Brent

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and below your substitution level there are infinitely many such computations. They all exist in arithmetic, and the FPI glues them, in a non computable way, in possible long and deep physical histories.
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Bruno

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http://iridia.ulb.ac.be/~marchal/

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