Re: subjective reality

[Bruno Marchal]

On 26 Aug 2005, at 23:48, [EMAIL PROTECTED] wrote: [BM]  I do think so. See Deutsch book which make clear that the MWI is based on comp. But it is explicit in Everett and in Wheeler assessment. From a strict logical point of view, ad hoc non comp theory of MWI can be built but it is really out of topic. [GK]  That may be Deutsch's opinion (though, again, I doubt he says anything like that in his book) but I have read both  Everett's thesis and both Wheeler's and DeWitt's defenses of it and in no way shape or form does anything like YD even figure in them!!! Literally, of course. YD is just a tools for explaining what it is "to be like an Everett  memory machine". It is implicit in reducing the quantum uncertainty to the ignorance of which branch we are in a superposition. Mathematically it can be justified by Gleason theorem or by Graham Hartle type of infinite "frequency" operator. See the Preskill's course on quantum computation which makes a nice summary. [GK]  Let me understand this: your aim is to derive QM from an hypothesis which, you know, is contradicted by QM ?!!!? Wow! I have already answered.  The current aim is to derive SWE (by which I mean the correct geometrical-gravity extension of Schroedinger Wave Equation) from comp. I don't expect to derive anything like SWE + collapse (although this is not entirely excluded!). What I have already proved is that  1) if you make the move from "SWE + collapse" to "SWE + comp", then from purely arithmetical reasons you are forced to go the the quite simpler theory "comp". This is the result of the UDA reasoning and you are invited to criticize it: it presuppose some "folk-psychology" and some passive understanding of Church thesis. See the slide of my 2004 SANE paper for a presentation is eight steps. 2) I translate that reasoning into the language of a large class of universal machine and got more constructive description of the physics you need (by "1)") to derive from comp. This is technically more involved. It suppresses the need of the folk psychology. Bruno http://iridia.ulb.ac.be/~marchal/