Le 28-août-06, à 07:42, Stathis Papaioannou a écrit :

> > Bruno marchal writes: > >> Le 26-août-06, à 16:35, 1Z a écrit : >> >>> >>>> And since the computer may be built and programmed in an arbitrarily >>>> complex way, because any physical >>>> system can be mapped onto any computation with the appropriate >>>> mapping rules, >>> >>> That is not a fact. >> >> >> It would make sense, indeed, only if the map is computable, and in >> this >> case I agree it has not been proved. Again UDA makes such question non >> relevant, given that the physical is secondary with respect to the >> intelligible. > > Any computation that can be implemented on a physical system A can be > mapped > onto another physical system B, even if B has fewer distinct states > than A, since > states can be "reused" for parallel processing. If B is some boring > sysstem such as > the ticking of a clock then the "work" (not sure what the best word to > use here is) > of implementing the computation lies in the mapping rules, not in the > physical > activity. The mapping rules are not actually "implemented": they can > exist written > on a piece of paper Honestly I am not sure about that. > so that an external observer can refer to them and see what > the computer is up to, or potentially interact with it. And if the > computer is conscious > because someone can potentially talk to it using the piece of paper, > ther is no reason > why it should not also be conscious when the piece of paper is > destroyed, or everyone > who understands the code on the piece of paper dies. In the limiting > case, the platonic > existence of the mapping rule contains all of the computation and the > physical activity > is irrelevant - arriving at the same position you do. OK, in the case the mapping rule can be coded in a finite way. For example I can code the computation of any partial recursive function by using a n-body problem. But a slight change in the initial position of one of the body would destroy the information, and it is not clear why some other *finite* working mapping rule would appear, even in Platonia. Computation is a much constrained notion than people usually realize. You may be right, but I have never seen any proof. The probable reason for this is that such a proof would need a much more formal approach to physics, including what happens in the bottom, but nobody knows what happens there, and current theories makes big simplification there (renormalization, etc.). I think that what you say is not totally excluded by string theory, but would be false with loop gravity, for example (in loop gravity everything is quantized, and I can build, if only by diagonalization, computation non mappable to any finite piece of loop-gravity-matter (if I can say). Bruno http://iridia.ulb.ac.be/~marchal/ --~--~---------~--~----~------------~-------~--~----~ 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 [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~----------~----~----~----~------~----~------~--~---