In a previous post I launched a kamizake assault on UDA which was justly cut to shreds on the basis of a number of misunderstandings on my part, perhaps most crucially my conflation of information and computation. I claimed that the UD cannot be distinguished from the set of all possible information states and therefore from an infinite field of static, within which all possible realities can be found, none of which, however, have the slightest coherence. I also mistakenly used the word 'random' to describe this bit field, which of course is wrong. I should instead have used the word 'incoherent'. Bruno and others quickly put me straight on these errors.

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I am still troubled however by the suspicion that UDA, by explaining 'everything' (except itself - there is always that lacuna in any explanatory framework) also explains nothing. Because the UD executes every computation, it cannot explain why certain computations (say Schroedinger's equation, or those of general relativity) are preferred within our presenting reality. This very universality also insulates it against disproof, since although it allows everything we see, it is hard to conceive of something it would disallow. David Deutsch's idea of a good explanation is one that closely matches the structure of the thing it describes, allowing for little variation. The vast variation in the possible worlds where UDA could be invoked makes it a bad explanation, in those terms. Of course the objection that nobody has yet found an application for UDA, a concrete example of its usefulness, is more of an objection to it as a scientific theory than a philosophical one. Still, I believe there is an argument against it at the philosophical level. The UDA invokes the notion of probability in relation to 1-p states on the basis of the "infinite union of all finite portions of the UD in which correct emulation occurs". Thus the indeterminacy of 1-p experience is a function of the distribution of states within the observer’s consistent histories. For instance, there’s a 20% chance of x happening, if it happens within 20% of my consistent histories. Please Bruno correct me if this is a misunderstanding. Now we know from QT there is a finite, if absurdly remote, probability of my turning into a giraffe in the next minute. So the UD, if not to contradict science as it stands, must allow this too. And indeed there is no reason for it not to, since there must be computational pathways that lead from human to giraffe - a sort of deep version of the morphing algorithms used in CGI - or a simple arbitrary transform. In fact there must be infinite such pathways leading to slight variations on the giraffe theme, as well as to all other animals, inanimate objects and so on - okay let’s leave out the inanimate objects since they possess no consciousness as far as we know, therefore no 1-p experience. Of course, these pathways are an extreme minority compared to the ones in which I retain my present form, behaving as we would expect on the basis of the past. But here’s where I see the problem. In a mathematical platonia we cannot make such a statement. The notion of probability within an infinite set is untenable. It is analogous to expecting that a number selected at random from the set of natural numbers is more likely to be divisible by 2 than by, say, a million. This is only the case of the set is ordered to appear this way, eg 1,2,3,4... If we write the set thusly: 1, 1 million, 2 million, 3 million, 2, 4 million, 5 million, 6 million, 3, 7 million.... etc then our expectation breaks down. So if there are infinite pathways where I turn into a giraffe, as there must be, there is no way for my 1-p experience to select probabilistically among these pathways. I can no longer say, if the set of calculation pathways is infinite, that giraffe transformation occurs in, say .000000001% of them, or 5%, or 99% of them. This is not a problem for an Everett -type multiverse, in which the universes are bound together by consistent physical laws which allow one to speak of a proportion of universes in which event x occurs. However, in a mathematical platonia where all possible calculations occur, and nothing outside of them, there can be no such ordering principle. I believe this same principle can be used to show that the calculations of the UD must be disorderly. Consider some calculation c which employs number n. In the UD there will also be a calculation which instead uses the number n+1, another which uses n+2 etc. There will also be calculations in which the ordering of the natural numbers is rearranged in arbitrary ways such as my example above. Instead of using simple n, the calculation will employ someFunction(n), where someFunction() transforms the number as per my example, i.e. (in pseudocode): if n modulo 4 = 0 return n else return (n-1) * 1,000,000 Thus the UD cannot rely even on the ordering of natural numbers to ‘prefer’ certain calculations, since the set of variants such as the above will be infinite, and overwhelm calculations involving simple n. Bruno? -- You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com. To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.