Danny Mayes writes: > First, regarding the idea of magical universes or quantum immortality > for that matter, doesn't this assume a truly infinite number of > universes? However, if you start with the idea that the reality we > experience is being created by a mechanical/computational process, > isn't it more likely that the number of universes is just extremely > large? Why should we assume the "creator" (however you choose to > define that) has access to infinite resources? Also, everything that > makes up our universe appears to have finite characteristics (per QM), > so it seems like every possibility within the parameters of the > multiverse could be covered by an enormous, but not infinite range of > possibility.

In some ways, infinity is a more plausible choice than some large number. After all, what number will you pick? A billion? 1.693242 sextillion? 10 to the 10 to the 10... repeated precisely 142,857 times? Any such number would be completely arbitrary. A fundamental theory about the universe should not have such magical constants in it. The only plausible numbers are 0, 1, and infinity. Maybe I'll throw in 2 if I'm feeling generous. Since evidently it takes more than 2 bits of information to create the universe, I think the simplest proposal is that there are no limits. > I think we are overlooking something here. It seems like there should > be a quanta of probabilty, just as there is (apparently) with time, > space, and matter. In other words, once the probability of something > happening falls below a certain threshold, it is not realized. Could > there be a Planck scale of probability? Does decoherence somehow keep > these strange events from occurring on a macro scale? It's possible. The concept of a special Planck scale is not part of QM. It is an incomplete attempt to merge QM with general relativity. Many physicists are coming to view our current attempts along these lines as unpromising. See Lawrence Krauss' interview in the new Scientific American, http://www.sciam.com/article.cfm?chanID=sa006&colID=1&articleID=0009973A-D518-10FA-89FB83414B7F0000 . We don't really know how it will work out, whether there are these kinds of thresholds for matter or space or energy. But if it does, then I suspect you are right and similar limits could exist for probability as well. Sufficiently improbable events might not occur in the MWI multiverse. (Of course there are other ways to get a multiverse.) Hal Finney