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Cosmic Darwinism featured in new view of the universe

  1. Aug 12, 2009 #1

    marcus

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    We should discuss Cosmic Darwinism. It is achieving prominence, so we should know something about it.
    To make the point about prominence, there's a book coming out called Beyond the Big Bang, that includes a chapter on CD, and here are some reviews of it:

    http://www.springer.com/astronomy/general+relativity/book/978-3-540-71422-4 [Broken]

    "Cosmology has now come of age. No longer a speculative backwater of science, cosmological theory engages with a plethora of detailed observations, enabling us to give a convincing account of how the universe exploded into existence in a big bang and evolved to the form we see today. But some deep and tantalizing questions remain unanswered. The stellar line-up of contributors to this volume are working at the cutting edge of cosmological research, and are poised to take our understanding of the universe beyond the big bang into an even stranger realm."

    -- Paul Davies

    "Was the big bang the true beginning of the universe? If so, what triggered this enigmatic event? If not, what came before it? This book provides a wonderful overview of current ideas on these ultimate cosmic questions, written by scientists working at the forefront of cosmological research."

    -- Alex Vilenkin

    Springer plans for the book to hit the market in December. So they have already gotten it out to reviewers so they have the reviews ready to pitch with. Paul Davies and Alex Vilenkin are worldclass reputations, so Springer is not doing half way measures. It's only August and we can hear the trumpets blowing already.

    Now the table of contents is available online and here is one of the chapter titles:
    Cosmic Darwinism: A universal differential selfreproduction via Black Hole-Big Bangs.
     
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  3. Aug 12, 2009 #2

    marcus

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    Now this idea of Cosmic Darwinism is connected with a testable empirical conjecture, which I and some other people are interested in, which you have to keep separate from the CD scenario itself.

    There are about 30 dimensionless constants that you need to plug into the standard models of cosmology and particle physics. Dimensionless means ratios, pure numbers like pi is a pure number, without any units attached to them. An example is the fine structure constant 1/137. Or the ratio of two particle masses.
    In addition to these Thirty there are Planck units based on hbar, c, and G which are NOT dimensionless. They are physical quantities, not numerical ratios. G, c, and hbar are not numbers. This discussion is not about them.

    Nobel laureate Frank Wilczek writes that there are 31 dimensionless parameters needed by the current models of cosmology and matter. Probably opinions differ, but for now something like Thirty.

    OK, the conjecture (proposed in 1992 and not yet disproved) is that in the observable universe these Thirty-some numbers are perfect for astrophysical black hole production. Technically the term is "local optimality" or "local maximum". The picture is a hilltop.
    No small change would improve things. An optimum point means there's no positive upwards slope in any direction.

    In the evolutionary fitness landscape, each species tends to be on top of its own hilltop. As a result of being moved up a fitness slope by selection pressure. On or approaching the top of whatever hill---not necessarily the overall highest, just the hill large or small where it happens to be. This is what "local" means.

    There are really two issues here:
    A. Is this local optimality conjecture true? Or can you come up with a small change (like a 5 or 10 percent change) in some one parameter or bunch of parameters that would have actually increased the abundance of astrophysical black holes. Can you prove it's not true?

    B. If it is true then how could this have happened? Why of all things would the Thirty be finetuned to make a lot of massive stars which each then collapses to hole? Such fine tuning calls for explanation.

    I'll get some source links in case anybody hasn't already read about this and is curious. We had a discussion about it recently in another Cosmo forum thread.
     
    Last edited: Aug 13, 2009
  4. Aug 12, 2009 #3

    marcus

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    Frankly, I like the blue issue more than the green. It is about a physically decideable proposition: something one can make observations and experimental measurments about, and which can motivate the growth of theoretical understanding.

    I'm not a big fancier of multiverse scenarios and the green issue can lead to some strange speculation. But first of all, it seems as if it might be out of order.
    Why invent explanations until you are reasonably sure that the optimality conjecture is true?

    Be that as it may, and regardless of one's preferences, the two issues come bundled. In the papers I have to cite as sources both these issues are discussed. Here are some, if you want to read up.

    http://arxiv.org/abs/hep-th/0407213
    http://arxiv.org/abs/hep-th/0612185

    I especially want to call attention to pages 31-33 of the 2004 paper because I like the technical reasoning (the blue issue stuff) about why it would have made black holes less apt to form if some of the main parameters had been a few percent different from their measured values.
    Some parameters discussed are the fine structure constant alpha (measured at around 1/137), the strong and weak force coupling constants, and the masses of some key particles. Remember that all these things can be expressed as ratios (to the appropriate Planck quantities, or to each other) and so are pure numbers, independent of units (that is what "dimensionless" means in this context).

    If someone is interested and has a bit more time, I would recommend reading more, say pages 29-34 of that same 2004 paper.
     
    Last edited: Aug 13, 2009
  5. Aug 12, 2009 #4

    apeiron

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    Not wishing to derail the thread before it even gets started, but I would make two contextual points.

    1) In theoretical biology, there is a key difference between evolution and development. So this may help explain why some people would feel the evo approach is in the wrong class of things to be a cosmological explanation. If devo normally comes first in nature, then cosmology ought to be a devo theory. But of course, this is also why have an evo approach seems so stimulating revolutionary here. (Personally I expect devo to still win out).

    2) For other reasons (dissipatively devo ones) I would think the universe is tuned optimally to the production of a flat and empty void. The infinitely expanded and cold heat death. So something else than black holes. The tuning so far as black holes are concerned would thus to be make them as sparse as possible so that they don't cause problems for the creation of a flatly expanding void. This would put an upper bound on their number/density, but not a lower one.

    But the black holes optimality conjecture is an idea in its own right. And as Marcus argues, it is interesting regardless of whether it ends up tied to a spawning multiverse scenario or some other cosmological tale.
     
  6. Aug 12, 2009 #5

    marcus

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    Right on Apeiron! I am so glad you see it that way. And because the optimality conjecture is an interesting idea, I strongly encourage people to try to disprove it!

    Perhaps it's the appealing ideas we should try to disprove, and test the hardest. I would like to challenge any reader, try to find one of the Thirty-some standard model numbers which, if you were to increase or decrease it a few percent, would make
    black holes more (rather than less) abundant.

    Frank Wilczek, Martin Rees et al list the dimensionless constants here
    http://arxiv.org/abs/astro-ph/0511774
    And pages 31-33 of the Smolin 2004 paper I mentioned already give a few key ones to play around with.
     
    Last edited: Aug 12, 2009
  7. Aug 12, 2009 #6
    I'm still struggling with the concept of a 'black hole' -- particularly if General Relativity has been used wrong -- as I suspect it has.
     
  8. Aug 12, 2009 #7

    marcus

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    Rymer, start a thread on it. What is a black hole? The question doesn't fit in here, have to assume some basics.
    Here we count simply what is identified by astronomers as a black hole. Their abundance can be estimated. Conventional.
     
  9. Aug 12, 2009 #8
    OK -- I might do that -- need to think about the wording.

    Just what ARE 'the Thirty'. Seems that if we are getting a correlation like this then many of there parameters must be interrelated.

    Further in order to determine such interrelations physical parameters (non pure numbers) must get involved.

    Reminds me of the old school math theorems -- before you can prove one you first have to agree what you 'know' -- i.e. which are likely to be assumed as a given -- assumption.

    Without that I don't see a good way to even begin.
     
  10. Aug 12, 2009 #9

    marcus

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    You say what are the Thirty. I already said in post #5
    They list them in this paper. And it is the Horse's Mouth. Wilczek is a Nobel particle physicist and Rees is the UK Astronomer Royal. I have to go, will explain more later.
     
  11. Aug 13, 2009 #10
    "Tiger got to hunt, bird got to fly; Man got to sit and wonder, 'Why, why, why?' Tiger got to sleep, bird got to land; Man got to tell himself he understand."
    -- Kurt Vonnegut -- Cats Cradle
     
  12. Aug 13, 2009 #11

    marcus

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    By chance (Bokonon says nothing happens by chance, it happened the way it was supposed to happen) I just happened to have reread Cat'sCradle this year. If you want the parameters of the StdMdl of particle physics explained to you you should probably start a thread in Particle Physics forum.
    But I will say that the around 30 numbers are a distillation of the questions "why why why" in Bokonon's little song or proverb. At present they are 30 essentials to our world that we can't explain. The most concentrated "why"s.
    If we could talk by ESP to someone in another universe and we wanted to describe all the basic physics and chemistry in our world---what are the chemical elements, what fusion is possible, what fission is possible, what reactions can happen, the strengths of all the forces between the atoms, the temperature at which water freezes etc etc then we could describe the whole thing by telling him about thirty numbers. He could work the rest out from just those.

    Those thirty determine all the masses and forces and stable chemical elements and compounds and melting points and how stars work and when they explode and when they don't, and they describe the early universe as well as now, and also describe the cold late universe (if you believe the standard models of cosmo and particle physics---which work fairly well).
    So you ask what are the Thirty. They are what we don't know why they are what they are, and which explain or determine the rest of basic physics/chemistry. So they are the most condensed description of our universe that we have----the most efficient way to communicate what our world is like to someone in a hypothetical other place.
    And that is a radical oversimplification. So if you want more take the Wilczek Rees link over to the other forum and ask them to explain the dimensionless parameters of the standard model.

    To go beyond the standard model, one thing we would like is an explanation for why those particular values of the parameters. Why is alpha = 1/137.
    So far no one knows why. And all the rest. At one time it was thought that some string scheme would explain the Thirty, but it didn't work out. That idea bombed in 2003, which some people had seen coming. But other people are still buying Brian Greene books! :biggrin:
     
    Last edited: Aug 13, 2009
  13. Aug 13, 2009 #12
    "Optimality" would seem to be but a disguised inverse on Einstein's puzzlement as to whether "God had any choice in the creation of the universe" For a functional cosmos, apparent alternatives may be illusory. Or, as Fred Hoyle put it: "The universe looks like a put-up job."
     
  14. Aug 13, 2009 #13
    There 30 parameters form a 'cloud' in 30-dimensional space.
    Our universe in some point in this cloud.

    The questions I have:
    * How big this clould is? Note: we should analyze all the aspects. For example, variation of some apraments won't affect star formation but could be fatal for the biology.
    * So can we define a 'shape' of that cloud?
    * for each border, can we define what will be 'falling apart'?

    More difficult question:
    * Are there any other isolated 'clouds' where life is possible? In different clould even chemistry might be completely different from ours. So this is a huge simulation task.
     
  15. Aug 13, 2009 #14

    marcus

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    There are actually more than one version of Cosmic Darwinism, several competing brands.
    This now is on the green question:
    If you accept that the Thirty parameters which describe our world at its most basic level are local optimized for black hole abundance, then how did that happen?

    The essential strategy in any brand of Cosmic Darwin is to think of a reproductive mechanism that results in a new spacetime region, and allows for a slight variation in the parameters. Then you can conclude that regions of geometry and matter will be favored that reproduce best.

    Personally I see more evidence that the universe likes black holes than that it likes intelligent life. There are a great many black holes already catalogued, and no evidence of intelligent life besides on earth. There may be some but it doesn't impress me as maximally abundant, it is not as if the Thirty were finetuned to produce it. So personally I don't bother considering reproductive mechanisms that involve the intervention of intelligent life. But some people have.

    Currently the most widely known brand of Cosmic Darwin is where astrophysical black hole formation is taken to be the reproductive mechanism---therefore causing the Thirty to evolve up to a fitness hilltop. Selection by reproductive success.

    Here is a recent paper by Gambini and Pullin on what black hole formation looks like in Loop. They don't support, or even discuss, Cosmic Darwinism. They just do the analysis in a limited toy-model case to find out what happens instead of the classical singularity.
    http://arxiv.org/abs/0805.1187
    This is hardly conclusive, but does seem that some kind of hypothetical reproductive mechanism seems to be emerging in the research literature.

    I still like the blue question better: are the Thirty really optimized for black hole abundance? Or can you find a way to modify them that would have produced even more holes than we have already? (Billions of galaxies and numerous black holes in each.)
     
    Last edited: Aug 13, 2009
  16. Aug 13, 2009 #15
    Marcus, why do you find it strange? I would rather say that it is difficult to avoid the formation of black holes. Even if we decrease G we just need to take more mass, and gravity will overcome any repulsion.
     
  17. Aug 13, 2009 #16

    marcus

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    Dima, I find optimality strange, when there is no explanation for it. Anything that looks like a fine adjustment, which one cannot improve on. That sort of thing seems to require an explanation of how it got that way.
     
    Last edited: Aug 13, 2009
  18. Aug 13, 2009 #17
    I agree that some parameters are optimal, and this is strange. But I don't understand why the number of black holes is 'optimal'.

    I can imagine a universe without black holes. It won't affect life (unless jets from black holes play important role in something)

    I can imagine universe with x10 black holes. Less matter, more junk.

    The only critical process for life is the supernova explosion, where all heavy elements are created. If gravity was too strong, there would be 'failed supernovas' instead and no heavy elements spread into space.
     
  19. Aug 13, 2009 #18

    marcus

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    Life is not relevant, really, to what we are talking about in this thread. Maybe I didn't make that clear enough. We are not assuming that the universe is optimized for life. So for the time being we can forget about life as an issue, right?

    The conjecture is that the parameters are adapted so as to make a lot of black holes. Adapted so well that no small change could produce an improvement---that is, and increase in the number of black holes.

    The question is, is this true or not?


    I don't think I said that the number of black holes is optimal. The conjecture is that the parameters are fine tuned so as to make many of them. This is, for example, what one would predict if one assumes that universes reproduce or have babies by making black holes. A universe with optimized parameters will be fertile---it will have a lot of daughters---and they in turn will be fertile and have still more. Universes which are reproductively successful will dominate the population---will be typical in some sense.


    This is a helpful point! Heavy elements are important in helping massive stars to condense from gas clouds. Carbon and Oxygen are especially important. Molecules of elements like C, N, O are good at radiating in the infrared. As the cloud collapses it develops excess heat energy which must be radiated away, or it will not continue to collapse. Molecules like CO help with this radiation. They are much better than hydrogen for this.

    So for a universe like ours to make a lot of black holes it should have plenty of supernovas, which seed the surrounding clouds with heavy elements such as C, N, O.

    Notice I am not talking about Life :smile: I am talking about the starforming process that eventually results in black holes. (It is an alternative point of view which may be unfamiliar to you.)

    Heavy elements distributed by supernovae also form dust. Dust may help to shield gas clouds in starforming regions from radiation whose pressure might disperse them. It is possible that dust also plays a role in the successful formation of a lot of massive stars.

    Your point about the importance of supernovae (not for Life but rather for black holes) is an excellent one. And this has some implication on the parameters that determine the relative strengths of forces.
     
  20. Aug 13, 2009 #19

    apeiron

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    It seems clear enough. If we are speculating that the universe is fine-tuned for intelligent life, then something about life has to act as the selective constraint on a multiverse.

    It was that line of thought that led to QM collapse type mechanisms where human consciousness was required to collapse the wavefunction of the space of possible universes.

    That was fun speculation for many years but never convincing. However it does demonstrate the nature of optimality arguments. What exists is treated as exerting the selective constraint on what might have been. You just then need some mechanism - like QM collapse - to do the actual constraining work.

    The black hole conjecture is about how black holes become the things that exist which constrain what was possible. They become the selection mechanism. Intelligent life in this scenario is neither here nor there causally. The existence of life is not part of the selection machinery.

    Of course, it is a stretch to imagine black holes being able to spawn infant universes. But again, the question of optimality itself can be asked separately.

    So there is a general cosmic darwinism where it might be intelligent life that constrains multiversal variety. Or black holes. Or something else - I think the constraints are probably actually very general, in the form of the second law of thermodynamics. So we are talking more about developmental processes than evolutionary ones.

    However the black holes conjecture seems a well posed problem. It can be easily distinguished from other selection-based, strong anthropic, mechanisms such as the idea that life itself may be what causes particular universes to be.
     
  21. Aug 13, 2009 #20
    So.. my first thought was the conjecture is irrelevant. If Cosmic Evolution isn’t postulating how in our Universes the 30 numbers are perfectly aligned to support our existence and evolution, that of intelligent life, why should we care?

    Then I saw this which seems the juxtaposition of my sensibility.

    “the importance of supernovae (not for Life but rather for black holes) is an excellent one”

    And this

    “Personally I see more evidence that the universe likes black holes than that it likes intelligent life. There are a great many black holes already catalogued, and no evidence of intelligent life besides on earth. There may be some but it doesn't impress me as maximally abundant, it is not as if the Thirty were fine tuned to produce it.”

    At the present age and expertise of our observational activities, that seems to be jumping to conclusions. Similar to waking up tomorrow with amnesia, walking outside, seeing a dozen cars parked on the street and concluding that the earth likes cars more then it likes intelligent life. Up until a little more then a decade ago blackholes were theoretical. Is it your position that we should have found intelligent life, on what must be insignificant and distant planets right, prior to discovering the most massive stellar objects ever theorized? And having not found intelligent life prior, the universe is relegated to being a baby black hole machine and we to the fungus on one of those insignificant distant planets?

    Further, using the logic (?) of Cosmic Evolution and from your quote, shouldn’t we conclude that the universe is “fine tuned” for the creation of stars vs blackholes?

    Also if a theory of everything was proven (talk about a natural selection process) would that spell the end to Cosmic Evolution? If not, how many “baby black holes” would you estimate each would spawn in this highly fertile world?

    Marcus, if I could quickly address your initial post to this thread.

    Including quotes from 2 prominent scientists who may or may not support Cosmic Evolution as you do (inference being they also do) but do support the book in whole is misleading at best. I recognize your affinity and enthusiasm for LQG and all things Smolin but still seems in poor form IMO.
     
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