OO's and BB's

By JoAnne Hewett | February 21, 2007 3:02 am

One nice thing about being a scientist, or at least an academic one, is that occaisionally you get your mind blown without any drugs or anything. Someone comes along and just pulls the rug completely out from under you – a total Denial of Reality Attack – and then you are left on your own to pick up the pieces.

Today at UC Davis we had a seminar from Don Page of the University of Alberta. The title and abstract of this talk sounded like science fiction, so I reproduce it here:

Don Page, University of Alberta

Title: Is Our Universe Decaying at an Astronomical Rate?

Abstract: Unless our universe is decaying at an astronomical rate (i.e., on the present cosmological timescale of Gigayears, rather than on the quantum recurrence timescale of googolplexes), it would apparently produce an infinite number of observers per comoving volume by thermal or vacuum fluctuations (Boltzmann brains). If the number of ordinary observers per comoving volume is finite, this scenario seems to imply zero likelihood for us to be ordinary observers and minuscule likelihoods for our actual observations. Hence, our observations suggest that this scenario is incorrect and that perhaps our universe is decaying at an astronomical rate.

Boltzmann brains? WTF? Intrigued, I went. This is a well-respected, highly-cited cosmologist after all. A former student of Stephen Hawking, no less. The jargon in the abstract, though bizarre, had a certain je ne sais quoi…

The idea Don put forward is this: there’s us, the ordinary observers (OO’s) in the world, who have achieved a certain stature after billions of years of evolution in the universe, and are now capable of making quite refined (or so we think) observations of the universe. Andre Linde called OO’s “just honest folk like us.” We’ve made it as a species, man- and womankind, and we’re figuring ou the really deep things that are going on like the Big Bang, genetics, and all the rest.

Then, though, there are the BB’s in the universe: Boltzmann Brains. Random fluctuations of the fabric of spacetime itself which, most of the time, are rather insignificant puffs which evaporate immediately. But sometimes they stick around. More rarely, they are complex. Sometimes (very very rarely) they are really quite as complex as us human types. (Actually, “very very rarely” does not quite convey just how rare we are talking now.) And sometimes these vacuum quantum fluctuations attain the status of actual observers in the world. But, the rarest of them all, the BB’s, are able to (however briefly) make actual observations in the universe which are, in fact, “not erroneous” as Don Page put it.

The man was a compelling speaker, and soon I realized there was an actual intellecutal debate underway in the high end of the cosmology/high energy community as to what the role of these BB’s might be in the universe, in the very far (or maybe not so far) future. We have a certain prejudice that, well, there just aren’t so many of them out there at this stage of the game, 14 billion years after the Big Bang. We’d like to think that we have the stage at the moment, we OO’s, um, assuming there are in fact more of us out there. (Any other non-human OO’s out there, could you let us know, please that you are listening? We have a few questions for you…)

The thing is, when you start talking about very very…very rare things like Boltzmann Brains, you are talking about REALLY long times. Much longer than we’ve had on earth (and I mean 4.5 billion years) by many orders of magnitude. Numbers like 10 to the 60th years were being batted around like it was next week in this talk. By those times, all the stars and all the galaxies have gone out, and gone cold, and space has continued to expand exponentially and things are long past looking pretty bleak for the OO’s still around, who (we presume) need heat and light and at least a little energy of some sort to survive, even if we are talking about very slow machine intelligence (even slower than humans for example).

So eventually, the mere fact that there is, at these long times, just oodles of space in the universe means that the BB’s become more and more common (even if they are rare) and eventually dominate the, uh, intellectual landscape of the universe. Of course this immediately raises all sorts of questions, such as mind/matter duality, the nature of reality and consciousness and multiple consciousnesses, perceived versus objective independent reality. Not to mention whether our “universe” is the only one. Okay, I’ll stop now…

Well, at this point in the talk, being new to this and my mind already quite blown, I had trouble keeping the thread. Somehow or other Don seemed to conclude that a BB-dominated universe was absurd (though are we sure we’re not in one already?) and then posited a radically different spacetime metric, an Anti-deSitter space, which he seemed to think might contain the problem. But then he hit another question which was the title of the talk: must the universe be decaying more rapidly than we expect? I am mangling this horribly, and of course before writing this I took just a glimpse at the already voluminous amount of literature on this topic, and realized that I have a lot of reading to do, both blog and academic. So it’s best I stop and let you all go look up Botzmann Brains, as I will, and do some more reading.

Sigh. The Ultimate Fate of the Universe is of course a nice escape from our quotidian grind. But, as Lenny Susskind wrote in his inscription to us in his book The Cosmic Landscape, at a signing last fall in Davis, “Hey, things could be worse!”

(And, Lo! They were worse…)

CATEGORIZED UNDER: Philosophy, Science
  • http://www.domenicdenicola.com Domenic Denicola

    Please keep up updated on what you find in the literature! This is absolutely fascinating; I quite concur with your opening sentiments.

    Also, Wikipedia seems to be in need of education about these Boltzmann brains… someone should write that article.

  • http://blogs.discovermagazine.com/cosmicvariance/sean/ Sean

    You can start reading on this very blog! This is definitely good stuff, and well worth thinking about — I’m working on a paper about it right now, in fact. It can tend to sound like crazy metaphysical speculation, but I would argue that these questions are precisely as physical and important as the horizon and flatness problems that everyone is happy to use to justify inflation.

    If you spend a lot of time in thermal equilibrium in a low-temperature universe, you will eventually make a lot of Boltzmann Brains. That’s why Don wants to appeal to a short lifetime, to avoid that problem. But we still have the problem of why there is any appreciable amount of matter at all — why isn’t the universe just empty flat spacetime?

    The good news is, you needn’t worry — you are definitely not a Boltzmann Brain. But we’re not yet sure why.

  • Alex Nichols

    Lenny Spiegel? Shouldn’t that be Susskind?

    We don’t experience intelligent observers popping into existence from quantum fluctuations though.

    Richard Dawkin’s Chapter on Cumulative selection in “The Blind Watchmaker” looks at the odds of producing the phrase “Methinks it is like a Weasel” using a computer program.

    Basically, longer than the time the universe has existed using single-step random mutation, versus a few seconds on a modern pc using cumulative selection.

    Of course, once you introduce a timescale of infinity anything’s possible!

  • DIS

    Damn right Sean! Crazy metaphysical speculation it is. It might be amusing to talk about in a blog, but you should use your talent for real science not this gobblediguck!

    The universe is not in equilibrium by any standard. It is even starting to accelerate. Sure looks like it is at an instability.

  • Robert the Red

    Isn’t this argument a kind of reverse anthropological teleology? “We don’t feel the domination of the late universe by Boltzmann brains to be plausible, so therefore the universe must cease to exist by then.” What kind of science argument is that? An OK one if you are sipping your fifth cup of soju, but otherwise pretty lameoid.

  • Stathis Papaioannou

    It occurred to me a long time ago that BB’s (although I didn’t call them that) were a means to immortality. All I had to do after I died was wait until the right configuration of atoms came about somewhere in the universe and I would continue to have experiences where I left off at the moment of death. I would have to wait a long time or the universe would have to be very large, but it’s not as if you notice time passing when you’re dead.

    But wait, it’s even better than this because we have functionalist theories of mind! This means my mind could be multiply realisable: on a brain, on a laptop running Windows XP, on a Klingon computer based on the radioactive decay pattern of a sacred stone. In general, there is a countable infinity of abstract machines that could realise my brain when physically implemented (meaning, loosely, that there is an isomorphism between the states of the abstract machine and the states of the abstract system).

    The implication of this is that I don’t have to wait zillions of years for the one “correct” configuration that will implement my brain, because at least one of the infinite possible configurations will come up somewhere every moment. You’re guaranteed of instant continuation after death, and in fact your next conscious moment will most likely be generated by this mechanism. If this conclusion seems wrong, then there is a problem with functionalism.

  • Douglas

    I’m sorry. Is this serious?

  • ZP

    Slathis, the only way for your brain to have the same configuration is if the universe you observe outside your brain also had the same configuration, which would be improbable to the point of impossibility, except in a cyclical universe. In addition, duplicating the same brain state you had at the moment of death may not be desirable. The only way you can continue where you left off, is if this is all just a dream, and you wake up into a greater reality.

  • http://www.math.columbia.edu/~woit/wordpress Peter Woit

    I would argue that these questions are precisely as physical and important as the horizon and flatness problems that everyone is happy to use to justify inflation.

    You’re serious about this claim?

  • Vince

    “Then, though, there are the BB’s in the universe: Boltzmann Brains. Random fluctuations of the fabric of spacetime itself which, most of the time, are rather insignificant puffs which evaporate immediately. But sometimes they stick around. More rarely, they are complex. Sometimes (very very rarely) they are really quite as complex as us human types. (Actually, “very very rarely” does not quite convey just how rare we are talking now.) And sometimes these vacuum quantum fluctuations attain the status of actual observers in the world. But, the rarest of them all, the BB’s, are able to (however briefly) make actual observations in the universe which are, in fact, “not erroneous” as Don Page put it.”

    I’m sorry if I’m not making a huge effort to read about this on my own (I have to go pretty soon!), but I hope there’s a more rigorous way of saying all this (with mathematics, perhaps) and some rigorous evidence for this. I mean, our abilities to make observations definitely depends on a properly-working brain, but isn’t there more to “an observer” than “complexity”? How can fluctuations of the spacetime fabric ever be “complex” enough to produce an observer, making observations? And what is meant by “observer” in this context anyway? Finally, I just don’t see how these spacetime fluctuations can be “complex” enough to produce something so ordered as the human brain. What is meant by “complex”? Through evolution, brains have evolved to be the main organ of the nervous system, and the origin of sentience (spelling?).

    I don’t know, I’m completely missing something here.

    Hmmm….isn’t there speculation in LQG that standard model particles are the twisting, etc. of the spacetime fabric? Must go…

  • http://backreaction.blogspot.com/ B

    reg. literature, he has a paper on that

    Is Our Universe Decaying at an Astronomical Rate?
    http://arxiv.org/abs/hep-th/0612137

    I read that a while ago, meant to write something about it, but then I took just a glimpse at the already voluminous amount of literature on this topic, and realized that I have a lot of reading to do, both blog and academic ;-) Sean’s post was quite enlightening in this regard. (But what I eventually wrote was too silly even for my blog ;-) )

    The only thing that I can remember two months later (this reflects the importance I give to the topic) was that the paper features some sentences you really shouldn’t miss. E.g.

    Consider imaginary humans who have a ‘youthful’ phase of 100 years of life with frequent and mostly ordered observations, followed by a ‘senile’ phase of trillions of years of infrequent and mostly disordered observations. Assume that [...]

    or

    First of all, the destruction of the universe would likely occur by a very thin bubble wall traveling extremely close to the speed of light, so no one would be able to see it coming to dread the imminent destruction. Furthermore, the destruction of all we know [...] would happen so fast that there is not likely to be nearly enough time for any signals of pain to reach our brains. And no grieving survivors will be left behind. So in this way it would be the most humanely possible execution.

  • Elliot

    This leads me to conclude, as others have (Kaufmann), that the emergence of complex structures is a fundamental property of our universe as opposed to being an accidental feature.

    If so then it would put a very different perspective on this discussion.

    Elliot

  • Aaron Bergman

    The good news is, you needn’t worry — you are definitely not a Boltzmann Brain. But we’re not yet sure why.

    But you could be a Boltzmann brain in a vat!

    (Solipsism in the landscape: the final frontier)

  • http://blogs.discovermagazine.com/cosmicvariance/sean/ Sean

    Sure I’m serious. The BB problem and the horizon/flatness problems are just different manifestations of the fact that the hot Big Bang model has very finely-tuned low-entropy initial conditions. You can either impose such conditions by hand (in which case none of these problems should worry you) or you can seek a dynamical explanation (in which case all of them should).

  • http://eskesthai.blogspot.com/2007/02/multverse-is-like-aflower.html Plato

    Hmmm… layman was wondering. A dynamical explanation?

    Boltzmann distribution. Binomial series. Ever heard of the marble drop/bean machine? Pascal’s triangle?

    What was the “initial condition” that allowed each “probabilistic future?” How were you to explain it? New numbered systems?

    So the BB had to be explicable in how that condition could be arrived at, and thus “any consequence” of that initial condition, as our universe?

    Sierpinski triangle. An outcome of “one possible universe?”

  • http://blogs.discovermagazine.com/cosmicvariance/john John

    I did indeed mean Lenny Susskind…a quantum fluctuation in my brain caused me to write Spiegel. Thanks for pointing ou tthe typo!

    – Joh

  • Vince

    “You can either impose such conditions by hand (in which case none of these problems should worry you)”

    The hand….of God, maybe? :)

  • http://pantheon.yale.edu/~eal48 Eugene

    And to think I am planning to give a talk on this stuff at Columbia next month :( .

    I do think that the objection of #4 about universe is not in thermal equilibrium is valid. And “Page’s Paradox” (as Don’s proposal is kinda known as) is bogus; one can’t really play the BB game simply by considering the “local expanding universe” (I can’t find a better word to describe it).

    This is not the same as saying the BB problem is not there of course, but that’s different from Don’s setup.

    Eugene

  • Alex Nichols

    “I did indeed mean Lenny Susskind…a quantum fluctuation in my brain caused me to write Spiegel. Thanks for pointing ou tthe typo!”

    Or perhaps Lenny Spiegel is the mirror-image Boltzman Brain version of Lenny Susskind….

  • http://quasar9.blogspot.com/ Quasar9

    Well, we do accuse governments of being short termist. Anything more than short term political gain – ie the next election means ‘little’ to a politician.

    But indeed in the cosmological scale of things, once we start looking 60 Trillion years into the future, has man become little more than an ‘anecdote’ or a blot on the landscape – after all if there’s 13.7 or 40 billion years behind us (before man puts in an appearance) only man could presume to speculate what may or may not be in 60 Trillion years time.

    If it is any consolation it is perhaps interesting to know that so much ‘history’ will take place – and though we may not be here to observe or record it – one could speculate that that is good, not worse. lol!

    But hopefully by then we (humans) will have evolved into beings composed entirely of photons – and be able to experience all (or at least see it) – without suffering from the decay. Or will photons seize to exist?
    I say, Who turned the light out?

  • Lee Smolin

    With all due respect to Don and Alex, who I’ve respected and liked for 30 years, this stuff is nuts. It is leading neither to predictions nor to explanations, and I would argue it can’t. But what is useful to understand is why it is nuts and why, nonetheless, it appears to many good scientists to be science.

    I think the first thing to say is that given the assumptions that go into most work on eternal inflation, the Boltzman’s Brain puzzle is a real puzzle. This is why good people who buy the scenario of eternal inflation are taking it seriously. But the conclusion I draw is that this is a reducto ad absurdum of the main assumptions of that approach to cosmology. In particular, the key assumption which I believe is wrong is that there is a timeless probability distribution on the landscape. While many good people are attempting to compute that distribution, the fact that it is hard to get out of the BB paradox suggests that there may be no such thing as a timeless, static probability distribution on the landscape.

    What is the alternative? In the case of Boltzman, the alternative was real evolutionary biology. Notice that Darwinian biology manages to be predictive and highly falsifiable in spite of there being no timeless probability distribution on the fitness landscape (which is btw where the term came from). instead, in biology, living creatures are relativerly fitter than non-viable creatures, but there is no extremization of fitness at any one time. This is partly because novel properties that influence fitness emerge from time to time from exaptation, in a way that is very diffiuclt, if not impossible, to specify in advance. The emergent properties that govern sexual selection in mammals could not be expressed in terms of the properties that goven fitness of bacteria. As a result, one can try to compute whether a given small mutation increases or decreases fitness of a real organism-and that is good enough to derive lots of predictions-but it would be useless to try to extremize fitness over the whole landscape.

    Similarly in cosmology, if we have to live with a landscape, but we want to be predictive, we should learn from what worked in biology and give up the notion that there is a single timeless probability distribution to compute, and instead start asking what makes a region or a baby universe more or less relatively fit than its near cousins. (The scenario of cosmological natural selection shows that taking this route does lead to falsifiable predictions for the same reasons that Darwinian biology is falsifiable.)

    Going a bit deeper, the governing assumption of eternal inflation is that there is a static and eternal population of universes that the fundamental laws of nature apply to more transparently than they do to our single, evolving, timebound universe, which is governed by only one theory at a time. Given that there can be no direct evidence for such an infinite and eternal multiverse, the interest in it must be driven by something other than observation. I am beginning to suspect it is because physicists would prefer to invent and think about something imagined to be eternal and timeless rather than try to explain what we observe in our universe entirely in terms of the information that comes to us from our past light cone.

    I suspect this reflects the expectation many people have that time is not fundamental, but rather emerges only at a semiclassical approximation in quantum cosmology. If you believe this then you believe that the fundamental quantities a quantum cosmology should compute are timeless. This in turn reflects a very old and ultimately religious prejudice that deeper truths are timeless. This has been traced by scholars to the theology of Newton and contemporaries who saw space as “the sensorium” of an eternal and all seeing god. Perhaps the BB paradox is telling us it is time to give up the search for timeless probability distributions, and recognize that since Darwin the deep truths about nature cannot be divorced from time.

    The alternative is to disbelieve the arguments that time is emergent-which were never very convincing- and instead formulate quantum cosmology in such a way that time is always real. I would suggest that the Boltzman Brain’s paradox is the reducto ad absurdum of the notion that time is emergent and that rather than play with little fixes to it we should try to take seriously the opposite idea: that time is real.

    Thanks,

    Lee

    ps some of the arguments aluded to are developed in hep-th/0612185, but they also are in my 1997 book on the landscape. I am also working on something new on these issues with the philosopher Roberto Unger.

    pps Before someone suggests that if we believe the evidence for inflation we have to believe in eternal inflation, let me mention that there is no convincing argument to that conclusion.

  • Aaron Bergman

    (The scenario of cosmological natural selection shows that taking this route does lead to falsifiable predictions for the same reasons that Darwinian biology is falsifiable.)

    No, it doesn’t. Cosmological Natural Selection is just a different choice of measure on the space of vacua, neither more nor less absolutely falsifiable than any other.

  • Matt

    So if I’m to understand all this, then at some point in the future, there WILL be a teacup in orbit around Mars? Not to mention a flying spaghetti monster? Invisible pink unicorns would still be difficult, I suppose, which is comforting.

  • Elliot

    Lee,

    You have argued that black hole production is the “trait” that gives provides “survival” value and the ability to produce offspring. Have you or others considered other “traits” that a universe might have apart from black hole production under the CNS paradigm that might be more amenable to proof or falsifiablilty?

    I am suggesting that perhaps the CNS model may be correct but the specific identification of black hole production as the trait leading to the production of offspring may be either incorrect or limiting in some manner.

    Elliot

  • http://eskesthai.blogspot.com/2007/02/multverse-is-like-aflower.html Plato

    Layman scratching head while faceless expression of Boltzmann puzzlement takes hold?

    How is one suppose to find “a equilibrium” in such a “low entropic state?”

    If we were to experimentally challenging any thinking with “relativistic processes” how could they have ever emerged out of the BB? Maybe, it was a “highly symmetric event” for any asymmetry to show itself as “discrete measures” defined in relation to the “energy of probable outcomes?”

    Where did such reductionism begin for us to ask about the “cross over?”

    We needed high energy perspective to realize that we were still talking about the universe. Are there any other processes within the cosmos that can be taken down to such rejuvenated qualities to new universes being born that while the arrow of time is pointed one way, that the universe itself allowed such expression to continue in the expansion rate, and the speed up?

    A Higg’s fluid? Something had to be “happening now” that would dictate?

    Forgive me here for my ignorance in face of those better equipped.

  • Alex Nichols

    I disagree with Lee Smolin and agree with Sean. In fact the “Boltzmann Brain” paradox actually disproves an absolute space-time.
    Occam’s razor suggests that intelligent observers only arise from cumulative selection in a biological framework which is dependent on the physical evolution of the universe.

    I don’t think Julian Barbour got very far with his attempt to dispense with time from quantum physics. At best it’s a valid insight, inasmuch as time can only be the measure of relational changes between particles (or wavefronts) But this insight does not lead to any predicitions about the future development of the system.

    So whether time is ontologically “real” or not, to all intents and puroposes we have to treat it as a measure of the entropy gradient we exist in.

    The question of what produced this gradient, whether a quantum fluctuation, a cyclic process or the multiverse is what cosmology is all about.
    I feel that some conclusions on these questions will be forthcoming from future observations.

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  • Stathis Papaioannou

    ZP on Feb 21st, 2007 at 9:37 am wrote:

    >Stathis, the only way for your brain to have the same configuration is if the universe you observe outside your brain also had the same configuration, which would be improbable to the point of impossibility, except in a cyclical universe. In addition, duplicating the same brain state you had at the moment of death may not be desirable. The only way you can continue where you left off, is if this is all just a dream, and you wake up into a greater reality.

    Not at all. I can build a computer which has the same configuration as yours if you give me all the requisite details, perhaps including inputs that you think are relevant, without reproducing you, your house, your suburb etc. But the predominant theory of mind these days, functionalism, says that a mental state is multiply realisable: on a digital computer, on an actual Turing machine, even on a large enough and complex enough wooden abacus. Given any computation, there is an infinity of possible abstract implementations of that computation, and an infinity of possible actual implementations for each of those abstract implementations. So if you are looking to implement any given computation by random processes, any one of these possible implementations will do, meaning that any given computation is certainly being implemented somewhere right now, without the need for infinite space and time. This argument has been used as a reductio ad absurdum against functionalism (for example, by John Searle), but the trouble is, there is no better theory out there.

    stathisp@gmail.com

  • http://eskesthai.blogspot.com/2006/09/cno-and-law-of-octaves.html Plato

    Neutrino Oscillations? Hmmmm…….

    Oscillating flavors The three neutrino mass eigenstates are presumed to be different coherent superpositions of the three flavor eigenstates (ne, nm, and nt) associated with the three charged leptons: the electron, the muon, and the tau. There is good evidence that only two of the three mass eigenstates contribute significantly to ne. In that approximation, one can write

    Just another fancy way of looking at CNO and the law of Octaves? :) While some thought space was empty, there were aspects of that space “which was alive” regardless of the asymmetrical realization of the discrete matters?

    I’m trying here. You needed a background for it?

    The triple alpha process is highly dependent on carbon-12 having a resonance with the same energy as helium-4 and beryllium-8 and before 1952 no such energy level was known. It was astrophysicist Fred Hoyle who used the fact that carbon-12 is so abundant in the universe (and that our existence depends upon it – the Anthropic Principle), as evidence for the existence of the carbon-12 resonance. Fred suggested the idea to nuclear physicist Willy Fowler, who conceded that it was possible that this energy level had been missed in previous work on carbon-12. After a brief undertaking by his research group, they discovered a resonance near to 7.65 Mev.

    Now I am not pro or against anything, just trying to make sense of the disparity of such anthropic reasonings. So what processes in Cern reveals such an idea? Muons?

    What’s that saying? The devil is in the details :)

  • Lee Smolin

    Aaron and Elliot,

    That CNS is falsifiable is based on genuine predictions. Here are two:

    1) The upper mass limit of neutron stars is less than 1.7 solar masses, due to their cores being kaon condesnates.
    2) Inflation, if true, is due to a potential governed by a single parameter, so that there is a relation between the number of efoldings and delta rho/rho.

    Both these predictions were published in 92, both could easily have been falsified in the years since, and still could easily be. (See hep-th/0612185 for the details, present status and references.)

    Eternal inflation + AP have made no such explicit predictions. My point is that the key difference responsible for the ability of one theory to yield predictcions and the inability of the other is that in CNS there is no time independent probability distribution on the landscape, there is just the prediction that the present values of the standard model parameters are near a peak of fitness (=production of black holes.) To do physics with eternal inflation you need a time independent probability distribution on the landscape, which is difficult due to the lack of a good normalization on an infinite set. To solve this you must resort to the AP, but that leads to the Boltzman’s brains paradox.

    Certainly there may be other cosmological scenarios on which a version of CNS could be based. Or, more generally, landscape scenarios that yield a time dependent, far from equilibrium distribution on the landscape, which is required to avoid the use of the AP and get falsifiable predictions. I would encourage people to look for them. I explored one other, related to the cold big bang (which Aguirre points out is a counterexample to the AP) but that didn’t work work.

    If I can add something general, Don argues that to avoid the BB paradox the universe must collapse on astronomical time scales. Isn’t it more likely that the theory that leads to this paradox has just come to a logical dead end? If so this is no shame, but lets try to understand why it fails so we can avoid making the same mistake again. I think its pretty clear that the problem is due to the way time is treated, so that the expectation that time is emergent leads to the requirement of finding time independent probability distributions on the landscape.

    Thanks,

    Lee

  • Aaron Bergman

    That CNS is falsifiable is based on genuine predictions.

    Just because you assert it doesn’t make it so.

    in CNS there is no time independent probability distribution on the landscape,

    Of course there is. That is precisely what CNS is. The old universes don’t die, after all, and even if they did, it wouldn’t matter. There’s no particular reason that we should be in a universe after many “reproductions” or one that is more primeval. Just like eternal inflation, you have a population of universes and a method of “reproduction”. You claim that this gives rise to a particular measure that’s highly peaked around the propensity to reproduce. Fine. That doesn’t change the fact that all the issues regarding measures in eternal inflation apply to your scenario, too.

  • http://eskesthai.blogspot.com/2006/12/gottfried-wilhelm-von-leibniz.html Plato

    A thought crossed my mind. A fictional story?

    It’s interesting what calorimetric measure can do when you are looking at cosmological events. So, the photon becomes descriptive in itself?

    Of course speaking of Glast here. Building alliances?


    Perhaps Quantum Gravity can be Handled by thoroughly reconsidering Quantum Mechanics itself?

    You are working “to set” the course of events? So we have this description then of the universe and it’s “phase transitions.” It’s behind the “value of the photon in it’s description and escape velocity” and it’s value also “gravitationally linked?”

    So technology now stops the photon in flight? We can then “colour our views with the gravitationally inclined?”:) A “philosophical take” on new computerized development with feeling?

  • Lee Smolin

    Aaron,

    I didn’t just assert that there are predictions, I state them and I give references where the full reasoning leading to them is presented. If you don’t believe these are predictions you have to explain why the reasoning is faulty. I don’t need to repeat it here, it was given in my 92 paper, in my 97 book and half a dozen places since.

    And no, there is no probability distribution on the landscape, just a prediction that there is a local maximum near our present values. This is very important, because it avoids the problems with making a timeless measure on the landscape. The assertion that we are near only a local maximum-with no claim that there even is a global extremum- is both enough to avoid those problems and sufficient to derive falsifiable predictions. Furthemore, I do not need to assume that the present parameters represent a global extremum nor that our universe is the most fit possible. This is the same as in biology, there may be more fit species in the future, but this does not prevent biology from being predictive because that depends only there being many mutations that will decrease our fitness from the present value.

    Indeed, none of this is new, this is now population biology has been done for decades. In works by theoretical biologists such as Stuart Kauffman they explain precisely why they avoid studying probability distributions on the whole fitness landscape for all possible biological species. The issues there are analogous to the issues in cosmology, but since they have a real theory that works and lots of real data they a long time ago understood how to do good science when faced with a vast landscape of possible species. I strongly suggest that anyone who wants to find a way out of the paradoxes and problems that so far block attempts to do physics with timeless probability distributions on the landscape should take some time to study the basics of population biology and theoretical biology. I suspect that once you understand how biology works you will not any more be tempted to compute timeless probability distributions on the whole landscape of theories!

    Thanks,

    Lee

  • Aaron Bergman

    Again Lee, the problem with the analogy to evolutionary biology is that your old universes don’t die. Plenty of them are hospitable to life, aren’t at local maxima of your fecundity function, and we could live in them. There is a landscape in your model precisely analogous to that in eternal inflation. If you want, you can, by fiat, take a global time slice and count the universes along that time slice with a counting measure, but that’s precisely what some of the measures for eternal inflation people do. Besides, I would think that such a strong proponent of background independence as yourself would be disturbed by the arbitraryness of this time slice. Unlike evolutionary biology, there is no universal choice of ‘now’.

  • Elliot

    Aaron,

    Can you precisely define the death of a universe as you describe it?

    Thanks,

    Elliot

  • Aaron Bergman

    Of course not. That’s the point.

  • http://eskesthai.blogspot.com/2006/12/against-symmetry.html Plato

    It was important to understand why there would be such divergences in perspective and how these would be lined up? Some of course did not want to take the time, but it was important to me to understand the “philosophical position” taken.

    Against Symmetry

    One could just as well venture to the condense matter theorist and said, what building blocks shall we use? One should not think the “history of Platonism” without some “other influences” to consider. Least you assign it to a “another particular subject” in it’s present incarnation? An Oscillatory String Universe?

    So the evolution here is much more then the “circumspect of the biological function,” but may possible include other things that have not been considered?

    Physiologically, the “biological function” had some other relation? So abstract that I assigned the photon? So I said “feelings,” while Einstein might assigned them to a “short or long time” considering his state of mind? :)

    More thought of course here on the “fictional presentation” submitted previous. As a layman I have a problem in that regard. :)

  • Lee Smolin

    Dear Aaron,

    Thanks. I agree that universes don’t die but this is not a problem as the population grows exponentially (in a global time picked to track the FRW time in the different universes). This means that there is a rate contant which is roughly the time between black hole creation events in a typical universe. If our univere is typical this is on the order of a second (10^18 black holes produced within a hubble time within the hubble scale). With exponential growth the vast majority of births have been within the past small number of time constants. So almost all universes born up to now were born since ours. So the population now is at least as optimised as our universe.

    I agree that there is a need for a global time to make this work. There can be global time functions in background independent theories. Two examples in classical GR with spatially compact boundary conditions are constant York time or constant imaginary part of the chern-simons invariant of the Ashtekar connection-this gives a global time function on the infinite dimensional configuration space of GR. There is also the proposal for a single global time in the unimodular version of GR where the cosmological constant is a constant of integration. Further, in a path integral formulation you can define observables as a function of an invariant global time, for example Sorkin’s proposal of past spacetime volume.

    So a global time function need not contradict background independence.

    Thanks,

    Lee

  • Aaron Bergman

    By appealing to the exponential growth in universes, you are explicitly making reference to a counting measure. Just because a measure happens to be highly peaked doesn’t make it philosophically different from any other measure. In that sense, your model is precisely as predictive as any other choice of measure. Now, the concentration of your measue may have consequences in a Bayesian sesnse of predicitivity, but to say that you’ve solved the philosophical questions associated with the multiverse just isn’t true.

    You can certainly define a global time function in any globally hyperbolic univese, but I don’t see how that addresses the arbitrariness of the choice.

  • Elliot

    Alright,

    As a layperson I need to ask a basic question here. How can there be any concept of Global Time outside the boundary of a particular universe. If there is no information flow between universes (causally disconnected) how can there be anyway to define time in the megaverse. Now I certainly can understand that individual universes can have “offspring” which creates temporal relationship. But this is a causal connection. If I am completely missing this point you can politely but firmly tell me to drop it but it seems that one distinction between CNS and eternal inflation is some notion of a causal connection in the CNS model.

    Elliot

  • Torbjörn Larsson

    Stathis:

    You’re guaranteed of instant continuation after death, and in fact your next conscious moment will most likely be generated by this mechanism. If this conclusion seems wrong, then there is a problem with functionalism.

    While I think physical consequences of BB or built brains are interesting and must be accounted for, as in the post or similarly in Aaronson’s constraints on the anthropic principle, I am less sure about philosophical consequences. For example, from what I gather about the difference in the BB problem for our universe not being in thermal equilibrium, it isn’t clear if the above is a real concern. See Sean’s link in comment #2.

    I can build a computer which has the same configuration as yours if you give me all the requisite details

    Are you sure? IIRC at n-category café someone claimed that not only can we not make a complete copy of a quantum system, but it is already impossible for classical ones. Maybe you only need to be close enough since there should be some robustness. But now you must ascertain that this is possible.

    any one of these possible implementations will do, meaning that any given computation is certainly being implemented somewhere right now, without the need for infinite space and time.

    The impossibility of copying may mean there is a censorship in place here. You can’t check if you were successful if you can’t ascertain that you are near enough to have a functionally equivalent system. And if you can’t check that the possibility of a vast amount of equivalent implementations gives an untestable result in your case.

  • http://eskesthai.blogspot.com/2006/10/probing-perfect-liquid.html Plato

    So no one knows how to combine thermodynamics and general relativity? Hmmm….Boltzmann puzzle…..and I slowly drift off in thought.

    Our work is about comparing the data we collect in the STAR detector with modern calculations, so that we can write down equations on paper that exactly describe how the quark-gluon plasma behaves,” says Jerome Lauret from Brookhaven National Laboratory. “One of the most important assumptions we’ve made is that, for very intense collisions, the quark-gluon plasma behaves according to hydrodynamic calculations in which the matter is like a liquid that flows with no viscosity whatsoever.”

    How does relativity ever arise out of such a situation? If “tunnelling was to occur” where would it occur, and where would “this equilibrium” find comparative Lagrangian relations in the universe? These perspectives are leading to what we see in the WMAP polarization patterns?

    Are there not “comparative features” that allows for the low entropic states, within the existing universe? Allows us to return to those same entropic states in their respective regions, while “feeding” the universe?

    You had to look for the conditions that would be similar would you not? And “supporting evidence” to explain the current universe speeding up. These conditions would have to support that contention.

  • Stathis Papaioannou

    SP: I can build a computer which has the same configuration as yours if you give me all the requisite details

    Torbjörn Larsson: Are you sure? IIRC at n-category café someone claimed that not only can we not make a complete copy of a quantum system, but it is already impossible for classical ones. Maybe you only need to be close enough since there should be some robustness. But now you must ascertain that this is possible.

    I don’t have to reproduce the coffee stains on the keyboard or the ripple in the power supply to produce a *functionally* identical computer; that’s the whole idea behind having standardised hardware and software. Similarly with brains, people can survive being shot in the head, never mind the change in the quantum state of a few atoms in duced by someone turning on a light switch in the next street. And that’s just if you want to reproduce a functionally equivalent biological brain. If it is possible in theory to preserve brain function by replacing each neuron with a computer chip, that is if the brain is Turing emulable, then a particular brain program could run on an infinite number of general purpose computers. If the BB is to reproduce the function of a particular brain, it need only chance upon the configuration of one of these machines, actual or (infinitely larger set) possible.

    stathisp@gmail.com

  • http://eskesthai.blogspot.com/2006/08/string-theory-landscape.html Plato

    Clifford has a good humour post about real estate in the extra dimensions. Of course you had to follow other discourses here to understand how one may view what is “current in the thinking?”

    This “balance in perspective” is not just one or the other but on how such perspective is formed around it. So on the one hand you have this Anthropic approach in string theory, and then you have the “philosophical differences on the other?”

    Your trying to explain it and in so doing revealing the train of thought that was established. One does not disavow the road leading to the physics established of course, and no where is this intentional on differing perspectives?

    Lee Smolin: “Here is a metaphor due to Eric Weinstein that I would have put in the book had I heard it before. Let us take a different twist on the landscape of theories and consider the landscape of possible ideas about post standard model or quantum gravity physics that have been proposed. Height is proportional to the number of things the theory gets right. Since we don’t have a convincing case for the right theory yet, that is a high peak somewhere off in the distance. The existing approaches are hills of various heights that may or may not be connected, across some ridges and high valleys to the real peak. We assume the landscape is covered by fog so we can’t see where the real peak is, we can only feel around and detect slopes and local maxima.

  • Jack

    The strange thing about the Boltzmann Brain story is that it is a story that we are all familiar with from undergrad days — you know, “please compute how long you have to wait before all of the gas molecules in this room move to the corner over there.” Of course it will happen, in accordance with classical statistical mechanics, if you wait long enough. So surely nobody doubts that BBs will eventually occur in our Universe if we are living in an asymptotically deSitter spacetime. I mention this for the benefit of people like Peter Woit who seem to think that the whole idea is just nuts. Talking about BBs is just ordinary statistical mechanics. But when you refuse to accept the conclusions of ordinary statistical mechanics, then indeed things will start to get kooky…..

    So why are Page and co so upset about BBs? It’s because they subscribe to Boltzmann’s idea that the arrow of time is due to a “rare fluctuation”. In other words, *we* are the products of a fluctuation just like the BBs, so the question is why aren’t we BBs?
    The answer, of course, is that *our* Universe is *not* the result of a fluctuation. For some reason that we don’t understand, it *had* to be born with an arrow of time. In other words, the BB argument is a proof by contradiction that Boltzmann’s idea is wrong.
    Now this is where things *do* start to get nutty. For people like Page and Vilenkin and Linde, the idea that inflation is just the result of some random fluctuation is almost impossible to give up. So they are driven to all kinds of kooky ideas to get out of this. But the very kookiness of their recent writings just underlines the point: Boltzmann was utterly wrong.

  • Lee Smolin

    Aaron, I am not claiming to have solved the deep problems, but I am proposing that they are insoluable within the framework of timeless equilibrium probability distributions or wavefunctions on the landscape. CNS is philosophically different for the reasons that I have already mentioned. I don’t want to bore everyone by just repeating myself, but let me emphasize that having a population that always evolves in time and never reaches equilibrium is very different from a time independent distribution. One way it is different is that one only has to make statements about local extrema near the parameters of our universe.

    Is this good enough? Its good enough for biology and so I propose it should be good enough for cosmology.

    Furthermore, it may be that the geometry of the landscape is not constructible in principle. This is true in biology, for the reason I mentioned which you can find elaborated on in the books of Stu Kauffman: fitness of organisms is determined by properties that are only sensible within a particular environment (flying is much less adaptive if there are no trees) and an organ of a species can be of value for a reason completely different than its precurser was in an ancestor (feathers which are good for warmth before flying can evolve to cover wings). Furthermore, as I argued in Life of the Cosmos and as Douglas has more recently argued the problem of computing the fitness function or of extremizing it may, be for all practical purposes (FAP) computationally intractable. If so, then there are two questions: how do we find the global extremum? How does nature?

    The point I am making is that we don’t have to answer either question if we treat the landscape like its name sake; the fitness landscape. This is because it is sufficient to generate predictions to posit that nature finds local extrema. To investigate this we do not need to have control over the whole landscape or be able to compute normalizable probability distributions or wavefunctions on the whole landscape. We just have to be able to investigate the local neighborhood of the actual standard model parameters. This is good, because it is undoubtably beyond our capability to identify all the regions on the landscape where structure and complexity arise.

    Thanks,

    Lee

    ps to Elliot, that is a good question. To a first approximation one can do something simple like count how many ancestors a universe has. This will approximate Sorkin’s proposal to use the volume of the past light cone of a point as the time function. If our big bang was born in a bouncing black hole singularity this extends through the bounce to the previous universe, and so on.

  • Aaron Bergman

    My point Lee, is that this is no less metaphysics than any of the other landscape stuff. There’s no justification for any of it. If you just want to consider “our universe is a local maximum of the fecundity function” as an axiom, you’re certainly welcome to, but I fail too see why that axiom is any better or worse than something like “we should do Bayesian analyses with respect to a measure on the space of vacua.”

    Regardless, it seems to me that in your writings on the subject, you explicitly justify your axiom by a population counting argument. Such arguments are implicit uses of a principle of mediocrity and a measure, so if you persist in such a justification (rather than just stating your axiom ex nihilo), you’re doing the same thing as the eternal inflation people.

    Either way, it doesn’t feel like science to me.

  • Gene Poole

    Hmmm…

    The assumptions which devolve from the current concept of the ‘big bang’ seem to be taken as true.

    Has anyone considered (yes I am really asking) that the ‘big bang’ is still ‘banging’, and is in fact the reason why the ‘universe’ (as a large pattern of standing waves) does not suddenly collapse to ‘zero’?

    We assume that the ‘big bang’ was a one-time event which created space/time, eh? In other words, space (an ‘expanse’ which seems to be expanding) and time, which is signaled by movement (known by us as ‘events’).

    A rough analogy: Just as we so-fragile Beings are able to survive the existence of our life-giving sun Sol, due to the distance and vacuum-insulation between us and it; so also our ‘universe’ survives because the energy of the bang-engine is at a safe remove (however defined) from our observed universe.

    What event precedes the collapse of a standing wave?

    And why does such a wave keep standing, absent that event?

    ==GP==

  • Tom Banks

    I hate myself for wasting any more time on this subject (having recently posted a paper on hep-th and then swearing I would stop thinking about it), but I see a lot of confusion and conflation of different things in the discussion. It should be admitted by everyone at the outset that they only have religious opinions on this subject, because we have neither experimental data, nor an agreed upon mathematical framework for discussing these issues. That said, here are my principles of faith:

    1)There is a particular model where Boltzmann’s Brains are definitely a problem.
    This is the Dyson Kleban Susskind (DKS) model, which is a modern version of Boltzmann’s old idea of explaining the low entropy initial conditions of cosmology as
    a random fluctuation in a finite system. In this model the log of the probability of getting an intelligent observer by normal cosmological and biological evolution
    is proportional to – R^2 , while that of thermally fluctuating an intelligent observer of mass m is – mR . I’m using natural units hbar = c = G = 1 here, and leaving out constants of order one. This model definitely predicts most intelligent observers should be BBs rather than OOs. So the model is definitely wrong, since its only excuse for focusing on the rather improbable history in the model which led to ordinary cosmology was that this was the way to get observers (Lenny S tells me that I should always emphasize that the DKS model was a straw man that DKS used to criticize the idea of eternal dS space).

    2)Time is emergent in quantum gravity. It is tied to particular observers, where here observer just means a large quantum system with many semiclassical variables (modeled in all known examples by cutoff local field theory). In general, as we see from Wheeler De Witt quantization (which I regard as a rough semi-classical guide rather than the basis for a rigorous quantization of gravity), the Hamiltonian is time dependent. One can conceive of a class of systems with the following properties: the set of initial conditions for the time dependent Hamiltonian, which describes our model for cosmology,
    splits into two subsets. In the first everything is constantly in equilibrium. In the second there is a long period of non-equilibrium in which intelligent life can arise through the usual cosmological/biological evolutionary route we all believe we have taken. It is possible but not proven that the holographic cosmology that Willy Fischler and I invented has this property. I claim that in such models it really doesn’t matter if the evolutionary period is followed by a much longer (if the whole system is finite, it doesn’t really make sense to talk about its behavior over recurrence time scales – see my nightmare paper with Fischler and Paban) equilibrium period where BBs abound. So what? Every history which gives rise to a BB also had a period when OOs were alive. The model doesn’t predict anything contradictory. It predicts two kinds of observers and our observations tell us which kind we are. If we invent strategies to live long enough (as a culture) we might even observe the other kind. In such models the BB is an interesting oddity like the fact that if we watch an undisturbed room full of air long enough, the air will all collect in a corner.
    It’s crucial here that the Big Bang is NOT just a random fluctuation in an equilibrium system, and that the Hamiltonian is time dependent.

    So, I believe there is a scientific issue here, that it can only be resolved by a theory of initial conditions and the Big Bang, and that there is a kind of behavior compatible with the rules of quantum mechanics of a time dependent Hamiltonian, which could explain what we see. In that context, a theory which ends in “eternal de Sitter space” will have BBs in it, but there is nothing contradictory about them and they don’t require us to assume the universe will decay on a time of order its current lifetime.

    I am unlikely to respond to comments on this, however provocative, for the reason outlined in the first sentence.

    Tom Banks

  • http://blogs.discovermagazine.com/cosmicvariance/sean/ Sean

    Tom, thanks for chiming in. Knowing that you won’t respond, let me just remark that there is something fundamentally unsatisfying with the claim that “this scenario predicts both OO’s and BB’s, but so what, observation tells us that we are an OO.” I think you really do have to worry about the counting. In particular, if you have a universe in which BB’s can arise, it’s probably also true that BU’s can arise — Boltzmann’s Universes, giant configurations which look indistinguishable from our current universe, except that they are really fluctuations from a higher-entropy past, not thermodynamically-sensible evolutions from a low-entropy Big Bang. In that case, there is no conceivable anthropic argument that would put us in the ordinary universe rather than the fluctuation; but nobody thinks we live in a BU, for good reason.

    Also I think that boundary conditions in the asymptotic past that are very different from those in the asymptotic future are wildly ad hoc, but that’s another argument.

  • Tom Banks

    Sean,

    Since it’s you, I’ll respond just this once. You’re wrong about BU. What fluctuates is states. The Hamiltonian is fixed and TIME DEPENDENT. There is nothing about the action of the asymptotic dS Hamiltonian in the future that resembles the time dependent hamiltonian that described cosmology (it’s EASY to prove this if you accept a few plausible things about the dS Hamiltonian). If you fluctuate a state, which corresponds to the state of our universe at say the time of nucleosynthesis, and act on it with the dS Hamiltonian, you won’t get anything like the normal history of the universe. Nothing will happen for a time of order the dS Hubble time, and on time scales much longer than that the evolution will have nothing to do with the cosmological history we’ve seen. This claim depends only on my picture of the QM of dS space. If you follow the full rules of holographic cosmology it’s even worse. The state of the universe at nucleosynthesis is a product of the state of things that could have been observed inside the particle horizon at that time, and a state of everything else. The holographic time dependent Hamiltonian slowly allows outside degrees of freedom to interact with inside ones. But the dS Hamiltonian does not respect this separation of the Hilbert space into a tensor product. It has big matrix elements mixing up all of the inside states with all of the outside ones: just as big as the inside inside and outside outside matrix elements (think of it as a random matrix on the whole hilbert space, with a few constraints on its spectrum).

    Your final comment about initial and final conditions also reflects a prejudice which comes from thinking too much about systems with time independent Hamiltonians and or time reversal invariance. And too much QFT in curved space time. It’s my belief that we won’t make progress on these questions until people smarter than I throw off these prejudices.

    I promise, NO MORE!

    tom

  • http://blogs.discovermagazine.com/cosmicvariance/sean/ Sean

    Fair enough, I won’t follow up! (Although I was thinking about fluctuating into our current universe, not into BBN.) But I will think about time-dependent Hamiltonians, which I admit I don’t have much intuition about.

  • http://eskesthai.blogspot.com/2007/02/newtons-space-was-sensorium.html Plato

    Wow! Interesting points being made here. :)

    I believe there may have been a misuse of the term “sensorium” above in post #21? That is can be used in “other contexts” as well. I give info on that for further inspection on my name if interested.

    What would “activate” the DNA in individuals that lies dormant now. I could not escape either the comment of Aaron’s about what was metaphysical. Has this then been relegated to a “philosophical difference” or was it always thus?

  • Jack

    Tom Banks writes:

    “I hate myself for wasting any more time on this subject”

    Thereby giving a powerful boost to the notion that the entire subject is not to be taken seriously. Gee, thanks Tom.

  • Stathis Papaioannou

    Tom Banks:
    “This model definitely predicts most intelligent observers should be BBs rather than OOs. So the model is definitely wrong…

    It’s a fiendishly difficult area when the observer self-samples. Is the Doomsday Argument right? Should I conclude that the number of non-human intelligences in the universe is relatively small because I’m not one of them?

  • Elliot

    Going back to my comment of #12 it still seems to me that the assumption that there is not an underlying principle or law that favors the emergence of complexity leads to this conundrum. I think I should amend that comment and say emergence and persistence of complexity. The other assumption is that we OOs or our successors or other OOs may not affect or alter the far future of the universe in radical and unimagined ways to ensure our own survival or that of our “offspring”. (baby universe or otherwise) To paraphrase Freeman Dyson we are already “disturbing the universe”.

    Elliot

  • http://eskesthai.blogspot.com/2006/10/history-of-star-shine-to-now.html Plato
  • http://eskesthai.blogspot.com/2007/02/colour-of-gravity.html Plato

    Sorry! The correct link can be found here.

  • Torbjörn Larsson

    Stathis:

    Sorry for not answering timely.

    If it is possible in theory to preserve brain function by replacing each neuron with a computer chip, that is if the brain is Turing emulable, then a particular brain program could run on an infinite number of general purpose computers.

    But this possibility is what I claimed earlier what you must establish. I can’t see that you have moved your argument.

    If the BB is to reproduce the function of a particular brain, it need only chance upon the configuration of one of these machines, actual or (infinitely larger set) possible.

    I think there is some confusion here, possibly on my part, since the possible improbability of deterministically copying a brain doesn’t preclude the stochastic probability of doing it.

  • Stathis Papaioannou

    SP> If it is possible in theory to preserve brain function by replacing each neuron with a computer chip, that is if the brain is Turing emulable, then a particular brain program could run on an infinite number of general purpose computers.

    Torbjörn Larsson> But this possibility is what I claimed earlier what you must establish. I can’t see that you have moved your argument.

    Brains are made of matter which follows the well-understood laws of chemistry. Certainly it would be very difficult, like simulating the weather, but how is it possible that a neuron will do something that is uncomputable? Roger Penrose has had to speculate on an uncomputable theory of quantum gravity just to keep the brain special, but he is almost alone in his position.

    Torbjörn Larsson> I think there is some confusion here, possibly on my part, since the possible improbability of deterministically copying a brain doesn’t preclude the stochastic probability of doing it.

    Wow, what a complicated sentence that was!

    stathisp@gmail.com

  • Torbjörn Larsson

    Wow, what a complicated sentence that was!

    I’m sorry, we do seem to have a communication problem which I cause, not least because I’m too tired when I have time to answer.

    Certainly it would be very difficult, like simulating the weather, but how is it possible that a neuron will do something that is uncomputable?

    My point here is that it seems to be (even classically) impossible in theory to copy a systems Hamiltonian perfectly. So it isn’t only the terribly difficult matter of copying the systems biochemical wetware and current state, or the even worse difficulty of copying into another type of system, but it is impossible to make a perfect copy.

    Therefore you must demonstrate that the deviations will still make a close enough copy to be a mind clone. It may be possible, since the we seem robust enough. But we don’t know. So you can’t claim ad hoc that it is possible, it isn’t exactly like copying a brick by dimension but it is like copying every sand particle and their binding forces in every detail.

    since the possible improbability of deterministically copying a brain doesn’t preclude the stochastic probability of doing it.

    What I mean is that even if it would be impossible of making a constructed copy, it would not preclude us or the universe to build bounded or unbounded many different brains. By chance someone might (will, in the later case) be a perfect copy of you and your thoughts from some moment and forward.

    But we can’t tell which one, because if it is impossible to make an exact enough copy, we can’t compare them either. This seems to preclude any possibility of you (being in the bounded category) making an exact copy and be certain of it, ie observe it. That would be a censorship principle.

  • Stathis Papaioannou

    Torbjörn Larsson >Therefore you must demonstrate that the deviations will still make a close enough copy to be a mind clone. It may be possible, since the we seem robust enough. But we don’t know. So you can’t claim ad hoc that it is possible, it isn’t exactly like copying a brick by dimension but it is like copying every sand particle and their binding forces in every detail.

    The brick has a particular function and a particular engineering tolerance for that function; you don’t need to specify it down to the quantum level. If the brain had an engineering tolerance of zero, random thermal motion in our heads would kill us instantly. Moreover, we do know that our consciousness can survive copying because it happens all the time: most of the atoms in your brain are replaced over a matter of weeks to months.

    Torbjörn Larsson >What I mean is that even if it would be impossible of making a constructed copy, it would not preclude us or the universe to build bounded or unbounded many different brains. By chance someone might (will, in the later case) be a perfect copy of you and your thoughts from some moment and forward.

    >But we can’t tell which one, because if it is impossible to make an exact enough copy, we can’t compare them either. This seems to preclude any possibility of you (being in the bounded category) making an exact copy and be certain of it, ie observe it. That would be a censorship principle.

    For an external observer that is so, but it isn’t a problem from your point of view if you are the one being copied. If you are instantaneously disintegrated and a sufficiently close copy of you is made within the event horizon of a black hole, no-one will ever be able to find the copy but you will suddenly find yourself as if magically transported there.

  • http://evolutionarydesign.blogspot.com/ island

    Elliot, I think that Lee’s idea about an inherent time asymmetry necessitates “an underlying principle or law that favors the emergence of complexity”, in terms of an energy conservation law that guarantees that the second law of thermodynamics never be violated, such as the one that is discussed here, in context with Richard Dawkins’ own ideas about the “anti-chance mechanism of natural selection”:

    http://pespmc1.vub.ac.be/ASYMTRANS.html

    … and as it is illustrated, here:

    http://pespmc1.vub.ac.be/ASYMILL.html

    … and on my blog, where my own ideas about “Our Darwinian Universe” are nearly identical, although less complex by orders of magnitude.

    The high energy physics mechanism for this is discussed in the following linked article, and many other places on my website. This is the same mehanism that is used in inflationary models, where mass can be created at the expense of a large negative gravitational energy following from expansion, except that the universe is held flat and stable as expansion accelerates toward the next big bang:

    http://www.lns.cornell.edu/spr/2006-02/msg0073320.html

  • Torbjörn Larsson

    Stathis:

    Moreover, we do know that our consciousness can survive copying because it happens all the time: most of the atoms in your brain are replaced over a matter of weeks to months.

    Well, not exactly. Many of our molecules are replaced by being broken down and reused. Metabolism supplies and removes some atoms when this happens.

    But much of our brain is static on the working cellular level, i.e. synapses and gate channels are added and removed but the neurons may not be replaced.

    But all that is besides the point, You have not explained how you will copy a brain close enough to be functionally equivalent with the original while continuing with the same state as when cloned.

    You are just claiming that it is possible. But that is not a demonstration.

    it isn’t a problem from your point of view if you are the one being copied

    This is exactly my point – without the possibility of an external observer no one will know if the copying succeeded. The clone will only know of themselves, and they can’t tell if they were successfully copied or not.

    But I think the problem with our communication is solved, if there ever was one. You are repeating your claims without addressing my arguments. I don’t think it is meaningful to continue.

  • Stathis Papaioannou

    Torbjörn> This is exactly my point – without the possibility of an external observer no one will know if the copying succeeded. The clone will only know of themselves, and they can’t tell if they were successfully copied or not.

    And how would you know you were the same person if you were kidnapped and taken to a distant place in your sleep tonight? Would you need to check with someone else?

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