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Weak and strong anthropic principle

  1. Oct 10, 2005 #1
    Can somebody post the diferences. To me they seem to be the same
     
  2. jcsd
  3. Oct 10, 2005 #2

    Garth

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    The Weak Anthropic Principle (WAP) simply says the physical properties of the universe are propitious for life somewhere within it.

    The Strong Anthropic Principle (SAP) says the physical properties of the universe must be propitious for life somewhere within it, that is there is some unspecified 'law' or reason why the various physical parameters have the values they do, and why this set of values are propitious for life.

    One explanation for the AP is that the are many, or even an infinite number, of universes and we are in this one because of a selection effect; we could be in no other. This is the WAP.

    However if the SAP is true then if there were many universes every universe would be propitious for life.

    As we cannot observe, and may never be able to observe, these other universes the scientific status of these explanations is somewhat in doubt.

    One example of the SAP is Smolin's Cosmological Natural Selection (CNS) theory, which suggests that universes are born out of the singularities at the centres of black holes and each new universe copies the physical attributes of its progenitor but changes them slightly. The universes then evolve to maximise the number of black holes they spawn, and these maximal conditions just happen to be also those that are propitious for life. After a certain number of iterations almost every universe would therefore be propitious and so here we are!

    However the fact that CNS requires the conditions that maximise the spawning of BHs should be also those that are propitious for life seems to be a bit of a coincidence. As the AP reflects on the 'coincidental' habitability of this universe it seems to me that for CNS to replace one coincidence with another does not really achieve anything.

    Garth
     
    Last edited: Oct 10, 2005
  4. Oct 10, 2005 #3
    So if life has a number of places it can arise, for example billions of galaxies, would this also be an example of the strong Anthropic Principle?

    Just out of curiosity, doesn’t Smolin argue that the Athropic Principle is unfalsifiable, and that CNS is an example of a falsifiable multiverse theory? Whether or not this is still Athropic Reasoning is unclear.
     
  5. Oct 10, 2005 #4

    SpaceTiger

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    If there were only one universe, I think we would be forced to resort to the SAP, regardless of the number of galaxies, because the subspace of conceivable laws of physics that don't produce galaxies at all is much larger than that for those that do. It's true that this universe has billions of galaxies in which life could potentially form, but if you change the fundamental parameters of our universe by a significant amount, it's likely that none of them will be able to produce life (in fact, the galaxies may not even form).
     
  6. Oct 10, 2005 #5
    I see, the number of galaxies is irrelevant if there is only one universe. In which case I would consider Smolin’s CNS to be closer to the WAP analogous to evolution where an emergent property comes about over a series of generations. In this light the SAP would seem to represent an intelligent design or creator, is this correct?
     
  7. Oct 10, 2005 #6

    SpaceTiger

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    That would be one example of the SAP, yes. I suppose one could also subscribe to the notion that the universe is just "here for us" and bypass the deity entirely.
     
  8. Oct 11, 2005 #7
    Certainly if our universe was the only one the SAP would be true but I think there cannot be a way of working this out. And until somedoby shows me the oposite I do not feel like joining the SAP
     
  9. Oct 11, 2005 #8

    SpaceTiger

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    I don't think anyone's trying to convince you that you should. The SAP is extremely unscientific.
     
  10. Oct 11, 2005 #9
    That 's what I was trying to say. Is fits better in a religious myth
     
  11. Oct 11, 2005 #10

    Garth

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    It all depends on what you mean by the Anthropic Principle itself and what it is used for.

    My favourite definition of the AP is Stephen Hawking's: "The world is as it is because we are", because it is so succinct.

    The WAP can be used to argue for the multiverse
    or, simply as a recognition that things could not be otherwise if we are around to recognise it.

    The problem with all these other universes is we cannot observe them, and may never be able to do so. Therefore belief in their existence is as much an act of faith as belief in a creating Deity.

    The SAP may be taken as an argument for the existence of such a Deity however, the cause that makes the set of physical constants propitious for life may equally well be a natural cause.

    As I said above Smolin's CNS is one such natural explanation why the anthropic 'coincidences' are so, they are the result of the natural selection for maximising a universe's black hole production.

    My caveat to Smolin's argument against the AP coincidences is to point out that if, the conditions that maximise BH production are also those that are propitious for life then, that itself seems to be a bit of a coincidence!

    Garth
     
    Last edited: Oct 11, 2005
  12. Oct 11, 2005 #11
    I can think in a universe born from every singularity. To me maybe appears more interesting this Wheeler thought about large amounts of paralel universes, without contact, with different constants... Well as it is imposible to prove its existence right now it all about believing it or not. Anyway I hope we will be able to discover if we are really alone or if there is life somewhere else in this or another universe. The only way is harnessing the space-time and I guess we won't be here when this has been one
     
  13. Oct 12, 2005 #12

    Chronos

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    I'm confident the WAP is the most unfalsifiable conjecture imaginable. But I don't see it as being predictive, merely a logical test of validity. I would argue that any observation that leads to the conclusion it is impossible to make such an observation has fatal flaws. Either the observation or interpretation must be incorrect.
     
    Last edited: Oct 12, 2005
  14. Oct 12, 2005 #13

    Garth

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    Yes the WAP is unfalsifiable in the sense that 'things' could not be otherwise; to our minds it is self evident because it is consistent with the existence of such minds.

    Garth
     
  15. Oct 13, 2005 #14

    Chronos

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    The other option is that 'God' [I don't mean the ' ' negatively, I like her immensely] has selectively shielded us from every observation that contraindicates our existence. I resist that argument. She is vain, has a great sense of humor, and is amused seeing us flop around on the grass like beached salmon. But, deep down, she likes us... every once in awhile, she whispers a word of wisdom to those willing to listen.
     
  16. Oct 13, 2005 #15
    I hope I’m reading that right, because when you use "she" in this particular context it sounds as if we’re an unplanned pregnancy. :biggrin:

    Religious dogma would be the first to resist such ideas that life was anything but special, it takes away their sense of self importance, their uniqueness. But likewise I see no reason why this should be the case.

    Perhaps Emergence is a better way of explaining physical properties?
     
  17. Oct 13, 2005 #16

    Chronos

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    Agreed, all physical properties are emergent from 'first principles', IMO.
     
  18. Oct 13, 2005 #17

    Garth

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    Emerging God by Philip Clayton an associate professor of philosophy at Sonoma State University in Sonoma, California.
    Did you hear about the right-wing fundamentalist who went to heaven? He found that not only was God black, but she was Jewish!

    We can't go on like this or the thread will be moved!!

    Garth
     
  19. Oct 13, 2005 #18
    Another emergence model is Tipler’s Omega Point Theory, where he puts forward his model for an evolving God as a scientific theory. Here G. F. R. Ellis and W. R. Stoeger offer a critique to his theory.

     
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