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Scientific alternative to the anthropic principle

  1. Dec 16, 2004 #1

    wolram

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    Scientific alternative to the anthropic principle by Baez
    http://arxiv.org/pdf/hep-th/0407213
    To me this is an heroic paper
     
  2. jcsd
  3. Dec 16, 2004 #2

    Garth

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    By Smolin actually!
    - but why "heroic"? I actually thought it was misguided!

    In the weak form of the Anthropic Principle (AP), "The world is as it is because we are" (Stephen Hawking) it simply acknowledges that any theory describing the universe has to predict properties that are propitious for life in order for it to pass the observational test that we exist in the universe.

    In that sense it does constrain proposed theories to be concordant with observation and predict constraints on physical variables, as we would not be here if otherwise.

    In an early paper on the AP by Carr and Rees, "The anthropic principle and the structure of the physical world" Nature, vol. 278, Apr. 12, 1979, p. 605-612, the authors point out the limitations of the AP, nevertheless they argue that even if explanations could be found for all the various coincidences in some "Theory of Everything", as Smolin's CNS purports to be, then the question would still remain, that out of all possible outcomes, why should it be that that theory is propitious for life and not otherwise?

    Of course the answer to this question may simply be, "A fluke", but others may choose to answer differently.

    Garth
     
    Last edited: Dec 16, 2004
  4. Dec 16, 2004 #3

    wolram

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    By Garth
    By Smolin actually!
    Apologies you are obviously correct.
    I use the term Heroic because the AP principle is a cul de sac, a place to go
    when no other alternative is obvious,
    cosmology seems riddled with unprovable theories ,Smolin is trying to close
    this particular cul de sac.
     
  5. Dec 16, 2004 #4

    Garth

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    I do not see why the AP should be a cul de sac, so long as it is used cautiously.

    For example, a few years ago there was conjecture about the existence of a fifth fundamental force. For the sake of the argument suppose we are at a time when such a force has just been discovered. It is coupled to matter (say) but the strength of the coupling constant "F" has not yet been measured, just as Newton discovered the law of gravity yet could not initially measure the value of G.

    Various theorists could take the fifth force and include it in various theories of QG, BB nucleosynthesis etc. They might find that if F < x or F > y then life could not exist in the universe, it would then be a proper use of the AP to predict that because we do exist then x < F < y.

    Would this not be a valid prediction? Am I missing something here?

    Garth
     
    Last edited: Dec 16, 2004
  6. Dec 16, 2004 #5

    wolram

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    By Garth
    For example, a few years ago there was conjecture about the existence of a fifth fundamental force. For the sake of the argument suppose we are at a time when such a force has just been discovered. It is coupled to matter (say) but the strength of the coupling constant "F" has not yet been measured, just as Newton discovered the law of gravity yet could not initially measure the value of G.

    Various theorists could take the fifth force and include it in various theories of QG, BB nucleosynthesis etc. They might find that if F < x or F > y then life could not exist in the universe, it would then be a proper use of the AP to predict that because we do exist then x < F < y.
    One could also come to the same conclusion in a logical way, without
    the AP, my point is as a stand alone tool the AP tells us nothing.
     
  7. Dec 16, 2004 #6

    Andrew Mason

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    Well, with our understanding of the chemistry of life (as we know it), we know that life depends on a few very important things: the geometry of the water molecule being perhaps the most important. In the absence of the anthropic principle, there is no explanation of why this should be. It just is. With the anthropic principle, it is more easily explained.

    It is like the geoanthropic principle (I just made that up). Ques.: "Isn't it lucky that the earth is so remarkably suitable for developing and supporting life?" Ans.: "No. Any place that question can be asked must be remarkably suitable for developing and supporting life." Thus, using the geoanthropic principle alone and without knowing anything about the existence of anything beyond the earth, one could conclude that there are many more places beyond the earth.

    Similarly, the anthropic principle points to the existence of many alternative universes beyond our own (in space and/or time). Ques.: "Isn't it lucky that the laws of physics of the universe are so remarkably suited to the existence of life?" Ans.: "No. Any universe where that question can be asked must be remarkably suited to the existence of life."

    AM
     
  8. Dec 16, 2004 #7

    Garth

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    I see the multiverse response as only one in a suite of such responses to the Anthropic Principle (AP).
    AFAIK these are:
    1. Its just a 'fluke' - The AP is a statistical argument, you cannot do statistics with a sample of one, the anthropic coincidences are just a brute fact with no further explanation.
    2. Its a selection effect - our universe is just one in a huge or infinite ensemble of other different universes and we are in this one because we can be in no other.
    3. There is some as yet unknown principle that forces any universe to take up anthropic values for significant fundamental physical constants. This is the Strong AP. Smolin's Cosmological Natural Selection theory may be seen as an example of such a principle. (If black holes spawn new universes then after a suitable number of evolutions any universe will end up maximising the occurence of black holes, which also results in them being propitious for life)
    4. The universe exists as a supposition of all possible quantum states, our existence as conscious observers has to collapse its wavefunction in such a way that permits our existence for the sake of logical consistency - Wheeler's Participatory AP.
    5. The universe has been designed to have these anthropic values in order to produce life forms within it.

    If you feel the latter point is unscientific because any such Grand Designer is beyond scientific observation then so are the other universes. The Grand Designer may be God or even a scientist performing the ultimate Big Bang experiment in a 'previous' universe. Of course such a scientist might then be thought of as God by inhabitants of this one!

    The fact that the AP points from physics to non-observable concepts, metaphysics, such as other members of a multiverse, or even God, causes some to question its validity. However you do not have to take that step if you do not want to, nevertheless the one thing you cannot deny is that, against the odds, this universe is propitious for life!

    Garth
     
    Last edited: Dec 16, 2004
  9. Dec 16, 2004 #8

    Andrew Mason

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    I agree.

    The irony of scientific achievement in the last 100 years is that we have gone from:
    1. a state in which the leading scientists of the day were suggesting that virtually everything knowable was already known (e.g. Planck's professor), to
    2. a state in which the leading scientists admit that we haven't a clue how to answer to the really fundamental questions.

    It is refreshing to see the humbling of science.

    There is, perhaps, nothing quite as annoying as an arrogant scientist, (eg. James Watson, co-discoverer of DNA) believing he knows the answers to the big questions. One has to ask the right question: In Watson's case he should ask: why are the laws of physics the way they are to enable water, DNA and other complex molecules of life to exist? Watson cannot begin to answer that.

    AM
     
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