Re: Peculiarities of our universe
- Original Message - From: Fred Chen [EMAIL PROTECTED] To: Everything [EMAIL PROTECTED] Sent: Saturday, January 10, 2004 10:17 PM Subject: Re: Peculiarities of our universe One other scenario is that a civilization has indeed reached this pervasive state, but not in a form we'd readily recognize. They may be nano-lifeforms or microorganisms, for example. This is probably harder to believe because only so much complexity can be stored in such an organism, but you never know. Maybe you could have trillions of these nonolifeforms that are no more than the eyes and ears of one superintelligent being.
Re: Peculiarities of our universe
One other scenario is that a civilization has indeed reached this pervasive state, but not in a form we'd readily recognize. They may be nano-lifeforms or microorganisms, for example. This is probably harder to believe because only so much complexity can be stored in such an organism, but you never know. Maybe you could have trillions of these nonolifeforms that are no more than the eyes and ears of one superintelligent being. AKA: some distributed intelligence's smart dust?; geez there really isn't anything new under the sun!
Re: Peculiarities of our universe
Hal, thanks for this comprehensive view about universes. This state of the Art essay is worth reading whether one concurs or discords. I concur with some tiny remarks (could it be otherwise???) The position that we don't 'see' other universes is correct, missing, however, the possibility of OTHER universes seeing US. Even interfere(?). Non essential style-wise - (you wrote): This observation points to the fact that with our laws of physics, the evolution of intelligent life is extremely unlikely. ... I would name our universe-system rather than the laws we abstracted from our (limited?) observations in our system-studies. Further: Presumably, there are universes whose laws make life essentially impossible. Characteristics (unobserved, in lifeless or intelligence-less universes: Yes. Laws? in different systems from any what we cannot even contemplate? No. I consider your measures in the widest (most general) sense as circumstances including features unknown to us as well. Since we cannot see other universes, I do not speculate about their particulars. Even possibilities of potentials are restricted to our experience and mindset. Our sci-fi is limited. Sorry for the hair-splitting and thank you for a good post John Mikes - Original Message - From: Hal Finney [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Sunday, January 11, 2004 12:57 PM Subject: Re: Peculiarities of our universe There has been a huge amount written about the Fermi Paradox (why are there no aliens). SNIP Hal Finney
Re: Peculiarities of our universe
On Sun, Jan 11, 2004 at 09:57:18AM -0800, Hal Finney wrote: [...] That is (turning to the Schmidhuber interpretation) it must be much simpler to write a program that just barely allows for the possibility of life than to write one which makes it easy. This is a prediction of the AUH, and evidence against it would be evidence against the AUH. evidence against it would be evidence against the AUH is similar to the Doomsday Argument. Let's assume that in fact universes with lots of intelligent life don't all have much lower measure than our own. Then AUH implies the typical observer should see many nearby intelligent life. Your argument is that since we don't see many nearby intelligent life, AUH is probably false. In the Doomsday Argument, the non-doomsday hypothesis implies the typical observer should have a high birth rank, and the argument is that since we have a low birth rank, the non-doomsday hypothesis is probably false. I want to point this out because many people do not think the DA is valid and some have produced counterarguments. Some of those counterarugments may work against Hal's argument as well.
RE: Peculiarities of our universe
Let X be some predicate condition on the universes in the multiverse. I think Hal is assuming that if all the following are true 1. X can be described in a compact form (ie it doesn't fill up a book with detailed data) 2. X is true for our universe 3. AUH = P(X)=0 then we deduce that AUH is (probably) false. Are you saying Wei, that there is a flaw in this logic? - David -Original Message- From: Wei Dai [mailto:[EMAIL PROTECTED] Sent: Tuesday, 13 January 2004 9:22 AM To: Hal Finney Cc: [EMAIL PROTECTED] Subject: Re: Peculiarities of our universe On Sun, Jan 11, 2004 at 09:57:18AM -0800, Hal Finney wrote: [...] That is (turning to the Schmidhuber interpretation) it must be much simpler to write a program that just barely allows for the possibility of life than to write one which makes it easy. This is a prediction of the AUH, and evidence against it would be evidence against the AUH. evidence against it would be evidence against the AUH is similar to the Doomsday Argument. Let's assume that in fact universes with lots of intelligent life don't all have much lower measure than our own. Then AUH implies the typical observer should see many nearby intelligent life. Your argument is that since we don't see many nearby intelligent life, AUH is probably false. In the Doomsday Argument, the non-doomsday hypothesis implies the typical observer should have a high birth rank, and the argument is that since we have a low birth rank, the non-doomsday hypothesis is probably false. I want to point this out because many people do not think the DA is valid and some have produced counterarguments. Some of those counterarugments may work against Hal's argument as well.
Re: Peculiarities of our universe
Why aren't we our own much smarter descendents? If you see quantum measurement events as 'uncovering' or 'choosing' from a larger set of, in some sense, pre-existing earlier possibilities, then this problem solves itself: the future looks 'bigger' than the present, but in terms of the real microstates, whatever they may be, it would be smaller. So your earliest observer moments would create a history of thermal, galactic, stellar, and biological evolution that traces back the shortest possible route to some sort of generic early universe condition with a very large measure. It is only the first of these evolutionary stages, explaining the origin of matter, that we do not yet understand. But I don't think we're to far off --Chris Collins - Original Message - From: Jesse Mazer [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, January 10, 2004 9:41 PM Subject: Re: Peculiarities of our universe One possibility for why we do not find ourself in an old, galaxy-spanning civilization has already been mentioned--perhaps after a certain point all the individual minds in a civilization unite into a single Borg-like hivemind, and this reduction in the number of minds might imply that the self-sampling assumption would predict we'll find ourselves in a time before this happens (although if the hivemind lasts for billions of years, the argument might not work because this individual mind would probably have more separate observer-moments than the total number of observer-moments of the hundred billion or so individuals who lived before the mind-merging). Another possibility is suggested by a theory about how the measure on observer-moments could be influenced by the likelihood of future duplications, which I discussed a bit in this post (in response to a post by Bruno Marchal discussing the same idea): http://www.escribe.com/science/theory/m4841.html If observer-moments which are more likely to have more copies of themselves existing in the future have higher measure, then this might also suggest why I find myself living before civilization has spread throughout the galaxy--perhaps observers who are alive right at the time when the technological singularity occurs are the ones who are most likely to become the earliest uploads and to have the most copies of themselves living in the future galaxy-spanning civilization, thus giving the pre-singularity versions of themselves a much higher measure than any post-singularity observer-moments. Jesse _ Learn how to choose, serve, and enjoy wine at Wine @ MSN. http://wine.msn.com/
Re: Peculiarities of our universe
Why don't we see Others? I think the anthropic principle neatly explains both scenarios: why we're here, yet nobody else seems to be. If life nucleation density is arbitrarily low (e.g. 1/visible univers) we still wouldn't fail to observe our existance. It is also worthwhile to mention that the deep universe is young, and hasn't yet bred sufficient amount of metals (in the astronomic, not the chemical sense), so due to delayed hatching we're not yet in the lightcone of an advanced culture. I.e., don't look at the visible universe without a probability bias, proportional but thresholded (no H/He life for sure). It is relatively straightforward to show that an advanced culture is expansive, in fact relativistically so, and everything past pioneer wave will be transformed to become unsuitable for an ursoup. Arguably, we're about to enter that expansive stage (notice that computational physics seem to allow cognition at a 10^6 speedup, so the time from zero to hero is less than a year), and we've only become observable within less than a century, the high-power emitters less than three decades. What's the probability to observe a 0.9 c pioneer expansion wavefront, which will kill subexpansive observers (observation window: about a century?), will prevent emergence of new observers, and will only start in systems with sufficient metallicity, with a yet unknown (yet probably very low) nucleation density? Arbitrarily close to zero, obviously. So I would be very, very surprised if SETI people actually found the sky hanging full of ~lighthour 300 K blackbodies, or even if we found independant life nucleation events within our solar system (which have to compete with impact ejecta crosscontamination, a very frequent event). pgp0.pgp Description: PGP signature
Re: Peculiarities of our universe
There has been a huge amount written about the Fermi Paradox (why are there no aliens) over the years, and I don't want to reiterate that here. You can come up with scenarios in which intelligent life is common but where they just aren't visible, but IMO such explanations are not very natural. Instead I propose that for the purpose of our discussion here, we accept the apparent fact that there are no other intelligent life forms within the visible universe. Then let us consider the implications with regard to the All Universe Hypothesis (AUH), which says that all universes exist. This observation points to the fact that with our laws of physics, the evolution of intelligent life is extremely unlikely. The question is, why? Not, why do our laws of physics make it hard for life to form, but why do we live in a universe whose laws of physics have this property? Presumably, there are universes whose laws make life essentially impossible. For example, they may be completely static, or equally bad, utterly chaotic. But on the other extreme, there must exist universes where intelligent life is common. At a minimum, we could create a such a universe in an ad hoc way by letting it be born full of intelligent life via forced initial conditions. And probably there are other laws of physics which would be much more congenial for the formation and sustenance of intelligent life than our own. So we have some universes which are full of life, others which are devoid of life, and others where there is a chance for life to form but it is relatively small. We appear to live in the third class. We talk about measure with regard to universes, and however it is defined, it seems that some such principle is needed to allow some universes to be more probable than others. Otherwise we have our flying rabbit paradox where the universe could suddenly stop being lawful, or could have arbitrary exceptions to lawfulness. Since there are more ways for things to go wrong than to go right, these exception-full universes would superficially be more numerous than those where the laws are universal. So there must be some property of the universal-law universes which makes it more probable for us to experience them than the others, and this is basically what we mean by measure. Universes with more measure somehow play a larger role in the multiverse and we are more likely to live in one of them. If universes with more consistent and uniform laws have greater measure, then this explains why we don't see exceptions like flying rabbits. However, it seems that the measure of a universe is not the only factor which should determine how likely it is to be observed; but in addition there should be a factor related to how many observers there are. The obvious case is for high-measure universes where observers are impossible. No one will observe such universes. This is the basic anthropic principle. But I would extend this principle to say that the probability of observing a universe is proportional to the product of its intrinsic measure and some factor relating to the number of observers in that universe. There are a few different ways this factor might work. The simplest would be to count the number of observers. A universe with similar measure but twice as many observers would be twice as likely to be experienced. Another possibility would be to use observer-moments. If two universes had the same number of observers, but in one they lived for twice as long as the other, then perhaps the second one would be twice as likely to be observed. Yet another alternative would be to base the factor on the fraction of the universe's total resources incorporated into observers, rather than just the number of observers. This would give a bonus to universes which were relatively efficient at creating observers, compared to universes which gained large numbers of observers merely be being inordinately large. The question of why we live in a sparsely populated universe, then, comes down to a comparison between the measure of a typical universe with many observers versus the measure of a typical universe with few. The former universes would get a large bonus factor for their many observers, while universes like ours don't have that. So for our observations to be consistent with the AUH, it must be that universes like ours have much larger intrinsic measure than universes with many observers. And since, as far as we can tell, our universe is not just sparsely populated, but extremely so, the measure differential in these two classes of universes must be extremely large. That is (turning to the Schmidhuber interpretation) it must be much simpler to write a program that just barely allows for the possibility of life than to write one which makes it easy. This is a prediction of the AUH, and evidence against it would be evidence against the AUH. On the face of it, this prediction doesn't seem too plausible to me. Of course, no one
Re: Peculiarities of our universe
- Original Message - From: Hal Finney [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, January 10, 2004 12:24 AM Subject: Peculiarities of our universe There are a couple of peculiarities of our universe which it would be nice if the All-Universe Hypothesis (AUH) could explain, or at least shed light on them. One is the apparent paucity of life and intelligence in our universe. This was first expressed as the Fermi Paradox, i.e., where are the aliens? As our understanding of technological possibility has grown the problem has become even more acute. It seems likely that our descendants will engage in tremendous cosmic engineering projects in order to take control of the very wasteful natural processes occuring throughout space. We don't see any evidence of that. Similarly, proposals for von Neumann self reproducing machines that could spread throughout the cosmos at a large fraction of the speed of light appear to be almost within reach via nanotechnology. Again, we don't see anything like that. So why is it that we live in a universe that has almost no observers? Wouldn't it be more likely on anthropic grounds to live in a universe that had a vast number of observers? Assuming the validity of the AP, we should expect to find ourselves in the most typical of circumstances. We should thus expect that most observers are similar to us. So, most observers are not part of a very advanced civilization. Maybe, as I wrote in the other posting, this is because those civilizations consist of only one individual. This should follow from the AUH, but it is not very clear how. If most observers are like us, then we shouldn't expect to find much evidence of intelligent life, even if there are hundreds of civilizations in our galaxy now. Maybe the fact that we are in a situation in which we don't have controll over our own bodies very much is a clue. This should again be a typical situation observers find themselves in. They are on the verge of understanding how the universe works, but they don't have a cure for deadly diseases or old age. They don't have the capacity to design and build observers like themselves. It should thus be the case that the moment they do develop such capabilities, their numbers should decline dramatically. This should be a universal property of civilizations evolving in a universe with large measure. The second peculiarity is the seemingly narrow range of physical laws which could allow for our form of life to exist. Tegmark writes about this at http://www.hep.upenn.edu/~max/toe.html. He shows a chart of two physical constants and how if they had departed from their observed values by even a tiny percentage, life would be impossible. In the full paper linked from there he offers many more examples of physical paramters which are fine-tuned for life. So why is this? Why does it turn out that our form of life (or perhaps, any form of life) can exist for only a tiny range of variation? Why didn't it turn out that you could change many parameters a great deal and still have life form? I don't see anything a priori in the AUH that would have led to this prediction. Now, it may just be one of those things that happens to happen, a fundamental mathematical property like the distribution of primes or the absence of odd perfect numbers. Self-aware subsystems just mathematically turn out to only be possible in a very tiny region of parameter space. Now, you might be able to make the argument that tiny is not well defined, that there is no natural length scale for judging parameter ranges. Tegmark could as easily have zoomed in on the appropriate region of his graph and shown a huge, enormous area where parameters could be moved around and life would still work. However I think there is a more natural way to put the question, which is, what fraction of computer programs would lead to simulated universes that include observers? And here, if we follow Tegmark's ideas, the answer appears to be that it is a very small fraction. (Of course, you still need to use your own judgement to decide whether that is tiny or not.) I am not sure this is correct, I do agree that there is a problem here. Tegmark looks at what would happen if you change on or more parameters in the standard model and then concludes that the parameter space for life is very tiny. Most physicists believe that a fundamental theory with only a few parameter, e.g. superstring theory, could be behind the standard model. The standard model is what you get if you ''integrate out'' the as of yet unknown physics at the smallest length scales. Given that the fundamental theory is supposed to have only a few parameters, it should have a much larger measure than generic versions of the standard model. So, the problem is actually worse: Why does life only emerge in a tiny fraction of programs describing versions of the standard model? And of those programs that do give
Re: Peculiarities of our universe
Hal Finney wrote: One is the apparent paucity of life and intelligence in our universe. This was first expressed as the Fermi Paradox, i.e., where are the aliens? As our understanding of technological possibility has grown the problem has become even more acute. It seems likely that our descendants will engage in tremendous cosmic engineering projects in order to take control of the very wasteful natural processes occuring throughout space. We don't see any evidence of that. Similarly, proposals for von Neumann self reproducing machines that could spread throughout the cosmos at a large fraction of the speed of light appear to be almost within reach via nanotechnology. Again, we don't see anything like that. So why is it that we live in a universe that has almost no observers? Wouldn't it be more likely on anthropic grounds to live in a universe that had a vast number of observers? Could be that 1. It's extremely rare to have a window for biological evolution to our level. (I highly recommend the well written basic-level but accurate and comprehensive new book called Origins of Existence by Fred Adams ISBN 0-7432-1262-2 which gives a complete summary of what had to happen for our emergence, and all the many ways how things could have gone differently, very few of which would lead to life anything like we know it.) 2. We're a distinguished member of the successful evolvers in the first available window-of-opportunity club. 3. If you believe 1 and 2, then note that we ourselves have not yet made galactically observable construction projects or self-replicating space-probes. Sure, we talk, but we haven't put our money where our mouth is yet. The (few, lucky to have emerged unscathed) other intelligent lifeforms in our observable universe may also not have done this within out lightcone (space-time horizon) of observability yet.
Peculiarities of our universe
There are a couple of peculiarities of our universe which it would be nice if the All-Universe Hypothesis (AUH) could explain, or at least shed light on them. One is the apparent paucity of life and intelligence in our universe. This was first expressed as the Fermi Paradox, i.e., where are the aliens? As our understanding of technological possibility has grown the problem has become even more acute. It seems likely that our descendants will engage in tremendous cosmic engineering projects in order to take control of the very wasteful natural processes occuring throughout space. We don't see any evidence of that. Similarly, proposals for von Neumann self reproducing machines that could spread throughout the cosmos at a large fraction of the speed of light appear to be almost within reach via nanotechnology. Again, we don't see anything like that. So why is it that we live in a universe that has almost no observers? Wouldn't it be more likely on anthropic grounds to live in a universe that had a vast number of observers? The second peculiarity is the seemingly narrow range of physical laws which could allow for our form of life to exist. Tegmark writes about this at http://www.hep.upenn.edu/~max/toe.html. He shows a chart of two physical constants and how if they had departed from their observed values by even a tiny percentage, life would be impossible. In the full paper linked from there he offers many more examples of physical paramters which are fine-tuned for life. So why is this? Why does it turn out that our form of life (or perhaps, any form of life) can exist for only a tiny range of variation? Why didn't it turn out that you could change many parameters a great deal and still have life form? I don't see anything a priori in the AUH that would have led to this prediction. Now, it may just be one of those things that happens to happen, a fundamental mathematical property like the distribution of primes or the absence of odd perfect numbers. Self-aware subsystems just mathematically turn out to only be possible in a very tiny region of parameter space. Now, you might be able to make the argument that tiny is not well defined, that there is no natural length scale for judging parameter ranges. Tegmark could as easily have zoomed in on the appropriate region of his graph and shown a huge, enormous area where parameters could be moved around and life would still work. However I think there is a more natural way to put the question, which is, what fraction of computer programs would lead to simulated universes that include observers? And here, if we follow Tegmark's ideas, the answer appears to be that it is a very small fraction. (Of course, you still need to use your own judgement to decide whether that is tiny or not.) In a way, then, these two questions are both related, and perhaps the same. They both ask, why so few observers? One question looks around the interior of our universe, and the other looks at the set of all universes. In each case, it seems that intelligent life is terribly uncommon. Hal Finney
Re: Peculiarities of our universe
- Original Message - From: Hal Finney [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Friday, January 09, 2004 3:24 PM Subject: Peculiarities of our universe There are a couple of peculiarities of our universe which it would be nice if the All-Universe Hypothesis (AUH) could explain, or at least shed light on them. One is the apparent paucity of life and intelligence in our universe. This was first expressed as the Fermi Paradox, i.e., where are the aliens? According to the anthropic principle, all conditions are such that our existence is possible. Also, all events up until now have been such that they favored our existence. This doesn't necessarily mean that those events were probable. In fact, they could have been wildly improbable. (that asteroid killing the dinosaurs at just the right moment might have helped us) Let us say you're repeatedly throwing a thousand dice on the floor, and that you are waiting for a pattern of fifty sixes to group close together on the floor. When they finally show up, it's doubtful that another distinct group of fifty sixes will show up in the same throw. In this analogy, the floor and dice represents (roughly) *this* universe and its galaxies and stars, and the groups of fifty sixes represent planets harboring intelligent life. After all, we seem to be very, very complex creatures. Most of the matter in the universe looks quite disorganized in comparison. Wouldn't this intuitive analogy explain why life is so rare ?