Actually, I might have to take some of that back. It may depend on how slow or fast you think our evolution was. It may be that in most of the universes in which there are observers looking back with the same observations that we make about how long it took for our civilization to evolve, there are others in that universe who evolved more rapidly (but for whatever reason haven't contacted them yet; maybe because they are too spread out and there is a speed of light barrier). In that case, we wouldn't necessarily expect to be the first civilization. And depending on how long you think it will take for a civilization to develop the capacity to simulate a universe in as much detail as we observe, we may in fact be living in a computer simulation after all. (Given the singularity, it seems like we probably would have that capacity at least in the next 1000 years, which is nothing in geological/evolutionary time.)
Even if our evolution represents the average, it seems that we would expect 50% to have evolved quicker, where many of them could easily have an edge of a 1000 years or more. Given the number of earth-like planets just in our universe, it seems we should expect many of those trials to have evolved more quickly than us. Then, if each produces just one simulation powerful enough for us to be unable to tell the difference, we might already be approaching a 50/50 anthropic prediction of being in a simulation. But we would probably expect them to produce lots of simulations, in which many of those observers are making the same observations about how long it took them to evolve. Thus, it may be that observers with the same evidence set as us who are in computer simulations greatly outnumber observers with the same evidence set as us who are in the real world and evolved slower than other civilizations. I wonder though if there could be some fundamental limits to the speed of computation. These thought experiments seem to rely on thinking advanced civilizations will be able to run a computer simulation powerful enough for us to be unable to tell the difference yet in a way in which it takes much less time. But can there be a simulation of the universe down to the last detail that runs quicker than the universe itself? I'm reminded of Stephen Wolfram's cellular automata, in which there appears to be no shortcut to how it unfolds over time. Unlike an equation in which one can just jump to some arbitrary value for x and determine y, the only way to see what the state of a cell is x steps in the future is to actually compute all the intermediary steps. So, maybe there could be many advanced civilizations before us but they wouldn't be able to compute the necessary intermediary steps significantly faster than the universe itself, at least not for the level of detail of the simulation needed to be able to generate our consciousness and fool us. But would it be feasible to have some selective computation of the details while simulating other stuff we don't observe at a higher level of description? I guess there's lots of tricky issues here. I'd better stop here and see if anyone else cares to try and make some headway. -Ku On 3/1/07, John Ku <[EMAIL PROTECTED]> wrote:
Hi everyone! I just joined this discussion list, which looks great by the way. I'm a philosopher by trade (mostly working on what we mean by things like 'reasons', 'ought's and 'values'), but I read a lot of science, including singularity stuff, in my spare time. I actually think there is reason to think we are not living in a computer simulation. From what I've read, inflationary cosmology seems to be very well supported. (Early exponential expansion of the universe explains things like observed flatness, homogeneity across distances, rarity of magnetic monopoles, and scale invariance of primordial density fluctuations.) Mathematical models of inflation point towards the process being eternal. There is some energy in space-time itself, which when dense enough causes expansion of space-time. But since that space-time will also have that vacuum energy, it fuels the expansion even more making it an exponential process. (Total energy is conserved because it is counterbalanced by gravity.) The upshot is that you have this multiverse expanding exponentially. Certain regions of it will, through quantum fluctuations, decay into a lower vacuum energy state that slows down the expansion and turns that energy into ordinary matter and energy. Thus, we get a universe like our's. Any spacetime regions that undergo decay, however, is more than made up for by the exponential expansion. Every second, there are 10^37 *more* universes being "born" than there were before. Thus, at any given time, the vast majority of the universes that exist are very young. So, I grant that it is *possible* that we are in a universe in which some other civilization has evolved enough to run simulations and we are just living in that simulation. But it will take a *lot* of seconds for that civilization to evolve. And each second, it will be vastly outnumbered by younger universes. The anthropic principle says to place an equal probability on being an observer with the same evidence set as you. Since there are so many more observers with these observations who are living in the real world rather than a simulation (given that young universes predominate), we have most reason to believe we are not in a simulation. I think this could also explain why we have not seen alien civilizations. Among all the universes in which there are observers who share our evidence set about our history, evolution, etc., there will be many more universes in which we were the first civilization to evolve than in which we came significantly after some other civilization. John Ku Philosophy Graduate Student University of Michigan http://www.umich.edu/~jsku On 3/1/07, Matt Mahoney <[EMAIL PROTECTED]> wrote: > > > --- Jef Allbright <[EMAIL PROTECTED]> wrote: > > > On 3/1/07, Matt Mahoney <[EMAIL PROTECTED]> wrote: > > > > > > --- Jef Allbright <[EMAIL PROTECTED]> wrote: > > > > > > > On 3/1/07, Matt Mahoney <[EMAIL PROTECTED]> wrote: > > > > > > > > > What I argue is this: the fact that Occam's Razor holds suggests > that > > the > > > > > universe is a computation. > > > > > > > > Matt - > > > > > > > > Would you please clarify how/why you think B follows from A in > your > > > > preceding statement? > > > > > > Hutter's proof requires that the environment have a computable > > distribution. > > > http://www.hutter1.net/ai/aixigentle.htm > > > > > > So in any universe of this type, Occam's Razor should hold. If > Occam's > > Razor > > > did not hold, then we could conclude that the universe is not > computable. > > The > > > fact that Occam's Razor does hold means we cannot rule out the > possibility > > > that the universe is simulated. > > > > Matt - > > > > I think this answers my question to you, at least I think I see where > > you're coming from. > > > > I would say that you have justification for saying that interaction > > with the universe demonstrates mathematically modelable regularities > > (in keeping with the principle of parsimony), rather than saying that > > it's a simulation (which involves additional assumptions.) > > > > Do you think you have information to warrant taking it further? > > > > - Jef > > There is no way to know if the universe is real or simulated. From our > point > of view, there is no difference. If the simulation is realistic then > there is > no experiment we could do to make the distinction. I am just saying > that our > universe is consistent with a simulation in that it appears to be > computable. > > One disturbing implication is that the simulation might be suddenly > turned off > or changed in some radical way you can't anticipate. You really don't > know > anything about the world in which the simulation is being run. (The > movie > "The Matrix" is based on this idea). Maybe the Singularity has already > happened and what you observe as the universe is part of the resulting > computation. > > My argument is that if the universe is simulated then these > possibilities are > unlikely. My reasoning is that if we know nothing about this > computation then > we should assume a universal Solomonoff prior, i.e. a universal Turing > machine > programmed by random coin flips. This is what Hutter did to solve the > problem > of rational agents. I am applying the idea to understanding a universe > about > which (if it is not real) we know nothing, except that shorter programs > are > more likely than longer ones. > > > -- Matt Mahoney, [EMAIL PROTECTED] > > ----- > This list is sponsored by AGIRI: http://www.agiri.org/email > To unsubscribe or change your options, please go to: > http://v2.listbox.com/member/?list_id=11983 >
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