Hi Bruno OK so there is a good deal of the technical stuff that I've got to catch up on yet before I can interpret what you are saying (although I think I can understand why the everettian imperative based on comp + UDA is there). However if I could for the moment get an intuitive understanding of what you mean by a consistent extension then perhaps that would help with what Brent brought up. From what I gather you are saying our next observer moment is based not on the laws of physics but on what possibilities the UD brings up in UD*. As an analogy, in conways game of life, the next screen output display (=OM for the little inhabitants) depends on the rules put into the cellular automata (I know this only accounts for a single little universe here and there would be an infinity of universal numbers for the real universe etc, but lets try to keep it simple for the sake of clarity). So in this game any (little) laws of physics (regularities in the game) are emergent and would become evident to a conscious entity that arose in the game. So here is a case where physics (regularities in the little world) arise from "a program". Is there any simple way this analogy or example can be adapted to demonstrate how the consistent extensions we experience come about. Does it have something to do with the prescription of the UD. If not then how does my existence pick its next consistent extension. It's all to do with what makes extensions "consistent". If it's not physics then it must be something and is there a simple analogy that can help me to grasp it? I find I can always work out the technicalities better if I have a "road map" or analogy to help.

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Best wishes Nick On Jan 6, 5:12 pm, Bruno Marchal <marc...@ulb.ac.be> wrote: > On 06 Jan 2010, at 01:21, Nick Prince wrote: > > > > > > > Hi Brent > > > Perhaps Bruno could give some clarification here. Just prior to his > > conclusion on the sane paper I quoted from was this: > > > "So if we keep comp at this stage, we are forced to relate the inner > > experience only to > > the type of computation involved. The reason is that only those types > > are univocally related to > > all their possible counterfactuals. This entails that, from a first > > person point of view, not only > > the physical cannot be distinguished from the virtual, but the virtual > > can no more be > > distinguished from the arithmetical. Now DU is emulated > > platonistically by the verifiable > > propositions of arithmetic. They are equivalent to sentences of the > > form ‘‘it exists n such that > > P(n)’’ with P(n) decidable. Their truth entails their provability, and > > they are known under the > > name of Sigma1 sentence. > > If comp is correct, the appearance of physics must be recovered from > > some point of > > views emerging from those propositions. Indeed, taking into account > > the seven steps once > > more, we arrive at the conclusion that the physical atomic (in the > > Boolean logician sense) > > invariant proposition must be given by a probability measure on those > > propositions. A > > physical certainty must be true in all maximal extensions, true in at > > least one maximal extension (we will see later why the second > > condition does not follow from the first) and > > accessible by the UD, that is arithmetically verifiable. Figure 8 > > illustrates our main > > conclusion, where the number 1 is put for the so called Sigma1 > > sentences of arithmetic." > > > It sounds as if Bruno thinks that the computations of the UD invoke > > our inner experiences and also our understanding of physics. Both > > come from arithmetical platonicism ( because thats what the UD is all > > about). So the pictures in the "film" are stiched together by the > > arithmetical (computation necessity) rather than the laws of of > > physics... Hmm not what I thought and said earlier!! > > > So according to Bruno the laws of physics come from something > > intrinsic in the computation? Not quite sure how. I just can't > > figure out any more at the moment and hope Bruno will give me a hint > > here. > > But the quote you give is the conclusion of step 7 and 8. Except that > I use a bit the vocabulary which will help to understand the > "interview" of the Löbian machine. > > Normally at step seven you understand that COMP + concrete UD => "I am > already in UD*" and the physical laws have to result from a sum on my > first person (hopefully plural) indeterminacy in UD*. (step 1 ->6 + 7) > > Then step 8, MGA, shows (is supposed to show) that COMP makes any > concrete running of the UD irrelevant. > (but the MGA thread in this list is better, I may send a new version > of MGA). MGA = Movie Graph Argument. > > This is not *just* because UD* is represented, remarkably enough, in > the elementary consequences of addition and multiplication, but mainly > because, by MGA, comp together with the physical supervenience thesis > makes it necessary to confuse a computation and a description of a > computation. The computation has to consist in the logical relations, > not in this or that implementation, (which, btw, can only be a > reduction to a particular universal machine). > > Do you see that COMP + concrete UD leads to an Everett-DeWitt shock? > We am multiplied by 10^100+ at each instant. COMP leads, naively, to > Aleph_zero + multiplication, or even 2^aleph_zero (in a sense)? > > Then MGA is the next and last difficulty. (before the machine > interview, if interested). > > Bruno > > http://iridia.ulb.ac.be/~marchal/- Hide quoted text - > > - Show quoted text -

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