Brian wrote > > > [Peter] > > > And if Platonia exists, it already contains every string that > > > could be output by the UD -- so what do you need a UD for? > > > > [Lee] > > It'll probably be retorted that it all has to do with > > measure, but there are lots of machines (I mean TMs) in > > Platonia, and lots and lots of them are a lot shorter > > (and so by any measure more plentiful) than the old UD. > > That's true, there are lots of shorter programs than the dovetailer. > But how many of those short programs support conscious observers? > Let's suppose you wanted to write a program that supports a conscious > observer. It's going to be a very long, complicated program right? > Very informationally complex. Well, I'm lazy. I would just write a > program that generated all possible programs then ran them. I would > then know that on some subset of those programs I've got conscious > observers. My program is considerably simpler than your program for > generating a conscious observer, it just takes a lot longer to > run.
Okay, thanks for that idea. But there is still the problem of measure to you, no? (I know Bruno has other ideas, and has explained them, and I think that there are a lot of ways people have spoken of regarding how to assign measure. Where are you?) That is, the UD will devote less than 1/10^10^10^10 of its resources to "running" the first conscious observer on the list of *all* TMs. On the other hand, I could believe that the rarity of a program DEVOTED TO RUNNING ME or (more regrettably, some other conscious entity) might be less than that. I.e., maybe only one in 10^^3. But more sensibly: d'you think that Schmidhuber or anyone has made a very good case why the UD would give me more runtime (i.e. observer-moments) than a specialized devoted program (which must also exist in Platonia)? > So it takes much less information to compute everything than it > does to compute one particular universe. I'm guessing the UD in its > most compact form is the simplest program for computing a conscious > observer! (know of any others?). And it is simpler than most of those > bitstrings appearing in its computational history. Yes. > > [Lee] > > Well, I think that David Deutsch's version includes all our > > latest and best physical theories, which still includes the > > Schrödinger equation and other time-based foundations. I'm > > guessing that the universes (I mean *slices*) are real; that > > is, have a higher ontological status than completely unrelated > > snapshots. But that would be just a guess. > > > > As for me, the whole multiverse as well as any slice strongly > > exhibits a dependence on time. > > I might be misunderstanding, but neither the multiverse as a whole nor > any slice of it is time-dependent. The laws of physics link snapshots of places with higher time clock readings with those with lower readings. I think that in FoR, slices *are* spacetimes, and are objectively linked together just as the pieces in a crossword puzzle are even though it's still in the can. Thus the linkage is dictated by the laws of physics. And almost all of those have this little parameter t in them. It seems to me that this might afford time a special role. But I'm still busy re-reading the chapter on Time; I know that I once agreed with every word, and thought that I understood it. But I'm a lot less sure now. Lee