On Fri, Jul 15, 2005 at 11:29:01PM -0700, "Hal Finney" wrote: > Another problem is that the UDist is not unique. Every Universal Turing > Machine (UTM) produced a different UDist. The one thing you can say is > that the various flavors of UDist do agree with each other up to some > constant that is independent of the object whose measure being calculated. > That's a good sign, but I am worried that it is not enough. > ...
I raise this particular problem in my "Why Occam's Razor" paper, and the solution to it turned out to be remarkably simple: The reference UTM (or more generally, reference interpreter) is simply that of the observer, so the universal distribution is relativised to the observer. The observer itself, I suppose is simply selected from a uniform distribution over all observers (which can by hypothesis be taken to be a subset of all UTMs, if one wishes). > > Another problem is that the MWI does not seem to fit too well into > this model. Basically, the universe described by the MWI is too big. > It's vastly bigger than the classical universe. > ... > > (This objection was also pointed out originally by Wei Dai.) > This, I think, is more of a problem for the ASSA than the RSSA. The RSSA basically describes a version of Darwinian evolution, and creates the needed complexity. This is kind of glossed over in my paper - I'm trying to expand on this notion in my book. ... > > So these are the major problems that I know of with the concept of basing > measure for all objects on the UDist, which then leads to Schmidhuber's > multiverse. In exchange for these though we do get some interesting > predictions and explanations, which I have largely posted before, but > here are a few of them repeated: > > 1. The physical laws of our universe should be expressible as a relatively > simple computer program, and likewise with the initial conditions. > Yes - the standard Occam's razor theorem. > 2. The universe should not be much bigger than it needs to be in order > to allow human beings to exist. > It is not obvious what this statement means. Sometimes it is simpler to be profligate :) > 3. There should be no substantially simpler computer program that can > produce observers nearly as easily as our universe does. > OK. > 4. There should not be vastly greater numbers of aliens in the universe > than humans. > Yes. This is also standard DA. > 5. There should not be vastly more human beings (or anything we would > consider observers) in the entire future of the universe than are > alive today. > Also standard DA. > 6. There should not be vastly more conscious animals in the world than > humans. > Yes - this is my ant argument, although the exact formulation takes some care, and requires some additional information. > 7. If it ever becomes possible to miniaturize and/or greatly speed-up the > human mind, we should be surprised to find ourselves as such a person > (unless that number of such minds is greatly increased to compensate > for these factors). I'm not entirely sure what you're getting at here, but it sounds like an ASSA-only type of prediction. > > 8. We will almost never find ourselves experiencing human observer-moments > that have much lower measure than typical ones (such as being a one million > year old cave man). > This is definitely an ASSA-only prediction - Jacques Mallah's argument in fact. > I see these as very powerful predictions for such a simple model, and True, but take care of additional assumptions creeping in. > my hope is that the problems with the UDist will be able to be cleared > up with continual improvements in our understanding of the nature of > computation. > > Hal Finney -- *PS: A number of people ask me about the attachment to my email, which is of type "application/pgp-signature". Don't worry, it is not a virus. It is an electronic signature, that may be used to verify this email came from me if you have PGP or GPG installed. Otherwise, you may safely ignore this attachment. ---------------------------------------------------------------------------- A/Prof Russell Standish Phone 8308 3119 (mobile) Mathematics 0425 253119 (") UNSW SYDNEY 2052 [EMAIL PROTECTED] Australia http://parallel.hpc.unsw.edu.au/rks International prefix +612, Interstate prefix 02 ----------------------------------------------------------------------------
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