I suspect that the answer to this lies in the concept of logical depth, introduced by Charlie Bennett. The universe needs to be simple, in a Kolmogorov sense, in order to get a high measure in the ensemble of all descriptions. However, the flip side is that in order to generate intelligent observers, it needs to be logically deep, ie run a computation for a long time. This is the explanation for cosmic time and space scales. In order to generate intelligent observers in a small universe requires a more complicated description of the physics generating it.
Of course, it would be nice to have a theory that gave order of magnitude estimates on the amount of computation required to generate intelligent observers, but at least the trends all point the right way. Cheers [EMAIL PROTECTED] wrote: > > One of the things that strikes me as most peculiar and unexpected about > the universe is this: that it is apparently finite and inhomogeneous in > time, yet infinite and homogeneous in space. > > >From what we can tell, the universe began about 13 billion years ago > and has gone through a series of phases or "ages" in which the dominant > physical effects have been strikingly different. And current observations > appear to indicate that the pattern will continue into the future, with > our current era of matter and stars being destined to give way to low > temperature and long-term effects. > > However at the large scale the universe shows no evidence of being finite > in size. Some models predict that it should be finite, but these aren't > very strong predictions given the struggles which cosmology is facing > these days. And even if it is finite as inflation models predict, it > is so huge that there is no real hope of distinguishing it from infinite > in size. Likewise the universe appears to be roughly the same everywhere. > Although there is clumpiness at many scales, there is no belief that the > average density or other parameters of the universe will be different > in widely separated regions. > > Is this something that might be predicted by a multiverse theory? > > It might be argued that the finiteness of (past) time is predicted by > the theory, because it is questionable whether it is meaningful to > have an infinite amount of computation in your past. > > The apparent infinitude of the spatial universe however does not fit > too well, for the same reason. If the universe is infinite then it > plausibly carries an infinite amount of information. This would require > an infinite amount of computation. Of course most of it is outside of > the "light cone" imposed by relativity, so perhaps this loophole in some > ways could avoid the need for truly infinite computation. > > Even if the universe is finite, it does seem extravagantly large. > It seems hard to justify such a size from anthropic arguments, especially > the sizes predicted by cosmological inflation theories. Surely humans > could have evolved in a much smaller universe, one which contains less > information and requires less computation. > > The universe seems to contain a lot more information than is necessary > for minds like ours to exist. Perhaps there are subtle reasons why such a > large size is necessary (for example, perhaps inflation is a side effect > of the simplest set of fundamental particles which would allow atoms to > exist and hence life to form, so we get a big universe as a side effect > of having simple physical laws at the microscale). But unless we can > find such linkages, this appears to count against an ensemble theory. > > Put another way, the all-universe model should predict that our universe > is little more complex than it needs to be for us to evolve. In effect > it predicts that such linkages will be found. > > Hal > ---------------------------------------------------------------------------- Dr. Russell Standish Director High Performance Computing Support Unit, Phone 9385 6967, 8308 3119 (mobile) UNSW SYDNEY 2052 Fax 9385 6965, 0425 253119 (") Australia [EMAIL PROTECTED] Room 2075, Red Centre http://parallel.hpc.unsw.edu.au/rks International prefix +612, Interstate prefix 02 ----------------------------------------------------------------------------