# Re: advice needed for Star Trek talk

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On 08 Dec 2010, at 22:15, Brent Meeker wrote:```
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```On 12/8/2010 11:19 AM, Bruno Marchal wrote:
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On 07 Dec 2010, at 22:40, Brent Meeker wrote:

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My reservation about step 8 is that the activity, in order to be a computation, must have an interpretation.
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Hmm... This is already a bit ambiguous. Suppose some (real) computer computes factorial(5). Some people could say that in order to be a computation of factorial(5) we need a human interpreting the physical process as a computation of factorial(5). I would not. But I agree we need here some 'physical' interpreter of the program.
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Suppose someone dream that he computes fact(5). Here we can agree that we need a physical interpreter interpreting or executing the brain so as to compute the "dream of the computation of the factorial by that person". But it is not the physical interpreter which computes the factorial, it is the dreaming person. And the person would be doing that computation even if nobody look at the brain and interpret that brain as "dreaming that someone compute factorial(5). OK?
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Sure, the person is interpreting the meaning, but I would say he is only doing so by reference to a world in which there are quintuples. It is because he can wake up and hold up his hand say, "I dreamed that this many fingers is prime."
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All right. Of course, (but you know this), he is living in the "standard model of arithmetic" where 5 is prime. Actually 5 is prime in all the models of arithmetic: it is stable universal belief.
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If the computation realizes "I'm thinking about the number 5." then "the number 5" must mean something in this context.
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It must mean something to the person thinking to the number 5. Not to someone observing that person.
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OK.

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Otherwise the same strings of symbols might compute, "I'm thinking of blxght." In order for "the number 5" to refer there must be a context in which the number 5 exists in some sense. This is fine for your theory and in fact that's how you ground it by noting that we all agree on arithmetic and that there is a number 5 in arithmetic. But then it seems the same applies to "I'm thinking of a chair." In order for that to be a possible interpretation of the strings there must be some referent for "chair". Of course you can say the "chair" refers to some bundles of computations of the UD that are related to "sitting" bundles, etc.
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Hmm... the ambiguity is present throughout that reasoning. I think. I will try to answer the next line:
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But then you are just saving the theory by mapping the physical world back into it.
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Once we assume comp, and assuming that the 'generalized brain' is the usual biological brain inside the skull (to make the pictures more easy), all we need is a computation of the relevant states of that brain.
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But here is where I think you help yourself to too much. It is only because the biological brain exists and evolved in a certain world that it has "relevant states". We as outsiders cannot generally observe what the brain is thinking about (it's as though it has invented it's own simulation code for the world), but you help yourself to the assumption that it is thinking about things - things that you and I can communicate about, i.e. are in our common world.
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But that point is valid both in the "real (putative) physical world" and in a simulation of the "real physical world" occuring in UD* (the entire execution of the UD). So, this kind of argument will not work for distinguishing the two. In both situations there is a referent relatively to the states of his brain, even if immaterial in the second case (but he cannot know that immateriality directly, or there is a magic, non Turing-emulable, property of "real matter" playing a role in consciousness).
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This create a human interpreter experience of "thinking" to the chair. That computation might be a dream by someone who know well about chair, and has seen many example of it in his memory-life. Now the UD will "generate", in his special static way, infinitely many computations going through those relevant states. They are all described by sequence of phi_i^n (j), n = 0 to infinity, with the different computations being distinguished by different i and j. OK? "n" represents the computational steps of the computation of phi_i(j), and the computation are really given by the arithmetical (and computable, in the mathematical sense) relation linking (i, j, n).
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For example phi_587610093811908883744 (45456901000456338867611906369579006532113536953) could describe the quantum state of a computer emulating that "human thinking of the chair", and many others with (actually) much bigger index i and data j. (note that even with the same i and j there are infinitely many computations, those being based on different universal interpreters.
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But each universal interpreter provides a mapping from such numbers to...what? another world, I think.
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You can call that an "another world", but those type of worlds are not distinguishable from just another universal computations. A good thing, because in fine, if you ask to a physicist what is (the scientific description of) a physical reality, he will just select one universal computation. He will say something like DeWitt-Wheeler equation + this or that initial condition, without reifying reality. Only an anti-comp, or anti-marchal (I mean anti-UDA), philosopher will insist on reifying matter. The trouble is that such a move makes either my brain non Turing-emulable, or introduces a curious physical supervenience thesis where either neurons have prescience, or where my consciousness depends on future contingent events.
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(below I will refer to ABOVE. It is here, I mean the paragraph just above).
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Some computation could emulate the quantum state evolution of the super cluster of galaxies including the Milky way, and thus the sun and earth and the guy thinking to that chair (and all his life with all its chairs).
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Now, UDA1-7 and the movie graph (UDA-8) shows that the guy, which plays the role of the interpreter of its own brain state is unable to distinguish any of those phi_i^n(j). Actually, it shows we cannot distinguish a phi_i(j) computed by the real "galaxy" if that exist, and the one emulated by the DU in arithmetic, emulating the same galaxy (at a level relative to the relevant state of its brain 'course).
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This is the tricky part. The same computation in the guy's brain can be interpreted as an emulation of the milky way or as thinking that five is prime. He provides the interpretation of the brain state - in his world.
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OK, except that "his world" is really "his most probable computational history". Typically, like in QM-without-collapse, he "belongs" or is "supported by" an infinity of computations "done" by the UD.
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The physical activity are the one described by those many computations, and this predicts that if the guy looks below its substitution level, he should find the trace of the infinitely computations going through those relevant states (by first person indeterminacy).
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Are you assuming that, at the substitution level, the interpretation is unique - regardless of which world it is in?
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That's the point. The interpretation is unique at the substitution level. That is why I say yes to the doctor and have to pray he has chosen the right substitution level. It is unique like the interpretation that the heart is pumping the blood is unique once the heart is substituted by a sufficiently genuine pump.
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Suppose someone says that for consciousness to exists we need the "real physical galaxy" (whatever that could mean). Then it means that whatever computations going through its states, none are enough for his consciousness to appear (he remains zombie).
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Or that computations must be physically realized and that determines where the consciousness appears.
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See ABOVE.

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But I'm not arguing that there must be a physical world (though that would be one solution). I'm arguing that there has to be a world that provides the interpretation of the numbers. I realize that this world can consist of just some class of numbers, but whatever it is, it seems to me it must be arbitrarily large and arguments about brain states and substitution are fallacious because they implicitly help themselves to the bigger world in order to ground their interpretations.
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Some reality has to provide the interpretation of the symbols, but that is exactly what a model does in logic. To interpret 0, s, +, x, we need a set (N) and the additive and multiplicative relations. That is why comp (DM) needs some amount of arithmetical realism. We don't need, and the argument shows we cannot need, to pick up any special universal function at the bottom. So we can take arithmetic, or the combinators, fortran, lisp, etc., and whatever is that choice, the physics will be given by a "sum" on all computations going through my actual finite computational state (which I hope my doctor has correctly delineate).
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But that means (assuming comp) that we have not choose the right level of simulation, and this means that we have to go deeper in the UD, using phi_i(j) with still bigger j and i. Or it means that the real galaxy contains something which prevent any emulation of it to appear in the UD, but that means that his generalized brain (of the guy thinking to the chair) is not really emulable by any computational process, and this means he should better say no to the doctor.
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So, depending of the substitution level, for emulating the right amount of "activity" we have to map sufficiently deep digital truncation of the 'physical world'. But that means that the real physics, from the point of view of the guy who has his first person (plural) reality) indeterminated on any of his relative incarnations in the deployment of the UD, will be given by the sum of all the truncated part of all the digital truncations of all the multiverses/multidreams in the whole (sigma_1) arithmetic.
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We will never been able to map the whole physics in one computation of the UD, given that physics is a first person (plural) view defined by all its digital incarnations in the UD, and that leads to a sum on the entire work of the UD (this really comes from both the invariance of the first person for the UD-delays, and step 8).
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So you have to really address the step-8 point, to reject immateriality, to link consciousness to something not Turing emulable. But then I'm afraid you have to attribute a physical role to object having no physical activity relevant to a computation done in "real relative time". That seems to me to be an ad hoc move close to non sense (assuming comp throughout). So consciousness is not related to a physical active brain, but to the infinitely many arithmetical relations relating those states.
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It is not excluded that *some* universal number (a "physics") plays special prominent role, but then, what the reasoning shows is that the existence of such number(s) have to be derived from the "arithmetical measure problem". The loss, is any simple basic physics (but then try to predict an eclipse with Feynman integral with all the decimal exacts). The gain, with the classical theory of knowledge, is that we get both the quanta and the qualia (by the G/G*, Z1/Z1*, etc. splittings).
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But doesn't that splitting depend on interpreting relations between computations as representing certain conscious thoughts? I don't reject it on that account, since if it can be shown to predict things that's as much as we ask of any theory. But it seems to me that you have so far only an analogy between proof and belief.
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At last. I was waiting that objection since more than 30 years!
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Bruno

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

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