On 9/27/2011 1:27 AM, Bruno Marchal wrote:

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On 26 Sep 2011, at 21:44, meekerdb wrote:On 9/26/2011 9:08 AM, Bruno Marchal wrote:Suppose that you are currently in state S (which exist by the comp assumption).But what does "you" refer to?Your first person view. Or the owner of your first person view, restricted to that view,without salvia amnesia, if you want.The comp assumption seems ambiguous. Is it the assumption that "you" are instantiatedby a specific computation?No. Something like that can be part of the consequence, but this is clearly not assumed.In fact the UD shows that "you" is instantiated by an infinity of computations.Or is it the assumption that your brain could be replaced, without you noticing, by aphysically different computer, so long as it computed the same function (at some level).Yes.These seem slightly different to me and are only identical if QM is false and the worldis strictly classical and deterministic. At a practical level the brain is certainlymostly classical and so I might say 'yes' to the doctor even though my artificial brainwill have slightly different behavoir because it has different counterfactual quantumbehavior. But this difference seems to present a problem when trying to identify "you"within the inifinite bundle of computations instantiating a particular state in the UDcomputations.Why? If my "original brain" is described by QM (without collapse) it might be said toself-multiply naturally. But that self-multiplication will be contagious on the UD inthat universe, so this will not change the relative proportion.

`That's the step that seems ambiguous. What you write above applies to a physically`

`realized (i.e. quantum) UD, but not to the UD in Platonia. The physically realized UD`

`will have non-zero probabilities of doing something random instead of implementing the`

`intended function.`

On the contrary, the UD itself forces a multiplication to be lived from inside.As to identify yourself in the UD*, this is just impossible in any third person ways.But the indeterminacy is on the first person experiences, not on their description inthe UD. So the statistics are lived from inside. A computation is winning, if indeed youfeel to be alive through its UD instantiation.Ambiguities remain, but they are part of the measure problem.Of course if you replace the whole universe with an emulation, instead of just mybrain, then my emulated brain in the emulated universe can have the same behavior as mynatural brain in this universe.Yes, and that is why the reasoning will work in the limiting case where your"generalized brain" is the entire universe described at some level. The UD will generateall the digital approximation of that universe, and at some level of approximation, youwill not see the difference, because we are assuming comp.The UD generates an infinity of computations going through that state. All what I sayis that your future is determined by all those computations, and your self-referentialabilities. If from this you can prove that your future is more random than the oneobserved, then you are beginning to refute rigorously comp. But the math part showsthat this is not easy to do. In fact the random inputs confer stability for theprograms which exploits that randomness, and again, this is the case for someformulation (à-la Feynman) of QM.How is this?Consider the iterated self-duplication experience, like with the random movie, where youexpect to see (correctly) a random movie. The movie will seem random because thelimiting case is described by a Gaussian (accepting the p = 1/2 for a singleduplication). Other considerations make such a randomness occurring below yousubstitution level, so it might be that the only way to stabilize the computations abovethe substitution level comes from some phase randomization, similar to Feynmanexplanation of why QM minimize the path action.

`So you're talking about keeping the computation classical, even though realized by a`

`physical device which is microscopically quantum? I don't recognize the reference to "the`

`random movie".`

We need a notion of negative (amplitude) of probability,

Negative probability or negative, imaginary probability amplitude?

extracted from comp, for such a procedure to work, but this is already provided by thelogic of self-reference when we add the non-cul-de-sac assumption (Dt) to theprovability modality (Bp), with p sigma_1. This can be made enough precise to make senseof how the quantum can be explained by the digital viewed from the digital creaturethemselves. No doubt that a lot of work remain to be done, but that is exactly what Iwanted to show.

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