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Behind the improbability of our universe

  1. Mar 26, 2014 #1
    I will be asking what is behind the fact that our Universe is a very special state which is very unlikely to have arisen by chance. But in the next 2 paragraphs let me give the basis for my question.

    Similar to the anthropic principle, but less debatable are the facts which Lee Smolin calls The anthropic observation: "Our universe is much more complex than most universes with the same laws but different values of the parameters of those laws. In particular, it has a complex astrophysics, including galaxies and long lived stars, and a complex chemistry, including carbon chemistry, These necessary conditions for life are present in our universe as a consequence of the complexity which is made possible by the special values of the parameters." from Scientific alternatives to the anthropic principle.

    More specifically there are about 35 parameters between particle physics and cosmology which have a free range of values but the values which we observe are nowhere near the values which are likely to be predicted a priori. Citing 2 values for example are 1) what Penrose calls the initial entropy problem in which he states an improbability value of 10^10^123 for our universe starting out in the state it did, and 2) the fine tuning of the dark energy or cosmological constant which is often cited as requiring a fine tuning of 1 decimal in 120 places to get the right number so that the universe wouldn't have collapsed on itself before it had time to form galaxies or accelerated at a runaway rate before it had time to form galaxies.

    My question is what is behind the astronomical improbability. I'm thinking there is an answer which is like, by analogy, the one given for abiogenesis. In the 80s Hoyle pointed out the exceedingly unlikely probability that life could arise by pure chance. The biologists countered by saying pure chance wasn't the only force at work and countered that natural selection was at work as well. But now we have the case of the evolution of nature itself. What can be doing the "selection"? I have read about underlying mathematical models and infinite multiverses, but these ideas don't seem very intellectually satisfying. And I have read that not much progress is being made on the TOEs, which hope to reduce the parameters down to a few.
     
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  3. Mar 26, 2014 #2

    mathman

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    The current state of physics conerning the 35 parameters is such that we just don't know enough. It would not surprise me if some future Einstein will discover a theory where these parameters are not that free.
     
  4. Mar 26, 2014 #3
    I too would be very satisfied with that result. Currently the cause of the universe's very special state seems unfathomable to me and that is ok because I realize science is always in a current state of knowledge such that we don't know as much as we will know in the future. But what I'm wondering is if there is any research into some guiding principle like "self-organization", which might explain the unique complexities we have in the universe. I cringe at the word "designed" but I wonder if it is scientific to exclude that possibility from our research.
     
  5. Mar 26, 2014 #4

    Drakkith

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    Given that our understanding of the laws of our universe is far from complete, what reason would anyone have of even using those computed chances? They are almost certainly wrong.


    Since most "designers" exist outside the realm of known physical laws and no known experiments could determine whether they really exist, yes, it is scientific to exclude them from our research.
     
  6. Mar 26, 2014 #5
     
  7. Mar 26, 2014 #6
    The problem as I see it is that we have only 1 explanation for the cause of our Universe and that is random chance. However, the resulting universe that we observe is calculated by our best current knowledge to have been extremely unlikely to have resulted from random chance. Therein lies the question, if chance alone than why the stupendous odds against? Or if not chance alone than what?
     
  8. Mar 26, 2014 #7

    Drakkith

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    That is incorrect. We currently do not have a working theory for the origin of the universe. We may never have one. It is one of the great unsolved problems in science.

    Note that the Big Bang Theory and the standard cosmological model do not explain the origin of the universe. They merely state that the universe was once in a very hot, very dense state and expanded from there.
     
  9. Mar 26, 2014 #8
    Drakkith raised a very important point. Cosmology deals primarily with what we can measure either directly or indirectly. As stated the hot big bang model makes no conclusions on the origin of the universe.

    Anything beyond that is speculation, often based on mathematic and scientific postulation. However its still specilulation. One could just as easily argue that the physics laws we understand in this universe will be the same as any other. Just as one could argue that this is the only universe. We have no conclusive evidence to support any conclusion beyond what we know of our own universe.

    The study of multiverses is oft termed cosmogeny just an FYI.
     
  10. Mar 26, 2014 #9
    It's not an unreasonable answer and it's easy to convince yourself that the notion of infinity is actually simpler than any finite number or quantity. I think you need to do that, to really see the merit of theories based upon multiverses, eternal expansion, cyclic model etc.

    Many argue that the notion of a multiverse requires proof and in the absence of testable predictions has no scientific value. Alternatively you can argue that it provides a simpler explanation for existing phenomena. It just comes down to which you find easiest to believe.

    Beyond that, there is the possibility that dark flow could offer experimental verification of a subclass of multiverse theories, should they provide a prediction that could be tested, by measuring it.

    Though it doesn't exclusively pertain to a multiverse, Weinberg used the anthropic principle to predict the value of the cosmological contant to an great degree of accuracy when most, if not all, other physicists were predicting exactly zero.

    It might all sound very fanciful, but there is grounding to it.

    Tegmark purports to have a ToE with no free parameters based upon exactly these ideas.
     
    Last edited: Mar 26, 2014
  11. Mar 26, 2014 #10
    It does not seem all that puzzling to me that, for the moment, our Universe supports life. The exact conditions under which our World supports life may be extremely 'unlikely', but it is easy to imagine some scenarios where life would eventually pop out into 'existence'.

    I have the word 'existence' in quotation marks because what exists and what does not exist is not very well defined. When most people use the word universe, they are referring to our observable universe. But our observable universe is not all-encompassing, nor can we (apparently) observe its ultimate source. In other words, we often ascribe 'existence' to that which is tangible or necessary for what we observe, but in absolute there is not necessarily any distinguishing quality of 'existence' (some might argue that logical or causal consistency is a distinguishing quality).

    Furthermore, the term 'life' is not all that well defined. At what point can you distinguish periodic behavior from self-preserving behavior from life? Natural selection plays a role in all of this in the sense that small timescale phenomena (perhaps smaller than the order of the age of our observable universe) that cannot be reproduced will not by itself come to form life as we know it.


    So when you talk about the 'unlikeliness' and fragility of human life and consider that we shouldn't be here, you should keep this in mind:

    If one attempts to define existence as something exclusive to our experience, then they've excluded all the other causally independent permutations that the entirety may have progressed through in order to finally produce life. So of course our particular parameters of existence are extremely unlikely, but that doesn't mean they shouldn't exist! For instance, when you consider the multiplicity of a particular state in a bounded thermodynamic system of infinitely compressible distinguishable particles, the likelihood that all the particles get smashed to one corner of the box (or bounding object or whatever) is very unlikely. But when you consider the fact that this particularly unlikely state is included within realm of all possible states, and that the existence of this state necessarily precedes the observation of the state itself (in the case of an existence compatible with life), you can see that this state must exist in order for any observation to take place.

    Under this (albeit philosophical and speculative) viewpoint, life as we know it was bound to happen eventually. As far as we know, we've only gotten the chance to experience roughly 80 years among the vast and incomprehensible expanse of eternity. Because of this ambiguity in defining what exists and what does not exist, because of the transcendent nature of the absolute, and because of the universal principle of "that which reproduces goes on to survive", one can argue that our overcoming the odds had to happen, and we have to be here now to experience it.
     
    Last edited: Mar 27, 2014
  12. Mar 26, 2014 #11

    Chronos

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    If the fundamental forces of the universe are emergent from a single source, what logic dictates they are 'free' to choose any value other than that they are known to possess? IMO, the universe is not fine tuned, it is self tuned
     
  13. Mar 26, 2014 #12
    Physics just creates and refines models. Systems of equations and constants. Some of these constants can't be derived and are just chosen to match observations. That's all we mean by a "free parameter". Models with less free parameters are seen as more elegant descriptions of nature, even though they have the same predictive power.
     
    Last edited: Mar 27, 2014
  14. Mar 27, 2014 #13
    Doesnt this argument require that we can predict whether or not life arises given a set of physical laws and constants of nature?
    I have to doubt this assumption.
    if i gave you the standard model of particle physics and the values for all the constants would you predict that our universe has life in it?
    I doubt it, the standard model has no dark matter, no inflation and not enough matter/anti matter asymmetry to generate the needed structures. You might also predict that dark energy is way too large to allow for life.
    In summary it seems for the one universe we can observe you would predict the wrong answer: that our universe has no life.
    So it seems we don't have good reason to trust the ability to predict whether or not a universe has life in it based upon physical parameters.
     
  15. Mar 27, 2014 #14
    Of course Drakkith is correct. I should have said we have only 1 explanation for the current state of our observable universe (not the origin) and that is chance alone (as opposed to natural selection working in addition to chance in the evolution of life). And still true is the paradox: the observed values of the current state are so unlikely that to assign the state to a result from a random set of actions nearly defies credibility. Therefore, something other than chance must have been be at work.
     
  16. Mar 27, 2014 #15
    So to you then, there can be no existence of a multiverse? ie, our observable universe and the space in which it is contained is the only space that can possibly exist

    I think the 'freedom' to choose parameters comes from the belief that there exists something beyond our self consistent laws of physics (like other self consistent laws independent of our own 'realm', but from the same ultimate source).
     
  17. Mar 27, 2014 #16

    Drakkith

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    Or it really could have been pure chance. It's unlikely, but possible.
     
  18. Mar 27, 2014 #17
    I like your byline:"It's not about what's possible, it's about what's probable."
     
  19. Mar 27, 2014 #18

    Drakkith

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    I'm a riddle wrapped in a bacon-flavored enigma, aren't I?
     
  20. Mar 27, 2014 #19
    You are unique, in a good way.
     
  21. Mar 27, 2014 #20
    Hmm bacon yum yum. Never tried riddle flavor before though
     
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