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Fine tuning - island of stability of our world

  1. Dec 25, 2008 #1
    I know some fine-tuning conditions which must be true in order for our universe, as we know it, to exist, for stars to shine and for the life to develop.

    For example,
    * CP violation (otherwise no matter because everything would annihilate)
    * Diproton (p+p) must be unstable (otherwise stars will burn out too quickly)
    * neutron should be unstable (important in the early universe)
    * dark matter exists (otherwise Jeans mass is too big in early universe - galaxies do not form)
    * there should be no stable particles containing 5 and 8 hardrons (otherwise stars will burn out too quickly)
    * etc, etc, etc

    My question is if there are any attemptx to create - not a full list of such conditions of course, but at least put in that list all we know - from astronomy, chemistry, star evolution, biochemistry etc.

    And them map these conditions to 30 parameters of the standard model + 2 parameters beyond standard model (percentages of DM and DE)

    I know the 'island of stability' is very small. But what exactly is it's size?

    P.S. More difficult question - are there any OTHER islands of stability which allow for life to develop (even chemistry might be completely different?)
  2. jcsd
  3. Dec 26, 2008 #2
    go to craigslist religion forum and do a search for 'fine tuning'. you will find a pretty good list.
  4. Dec 27, 2008 #3


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    You dont need fine tuning to find worlds such as ours, just blind luck. Many worlds like ours surely exist in a universe as large as ours.
  5. Dec 27, 2008 #4
    Wih different parameters of the SM? Sure, but in most of them there are no observers
  6. Dec 27, 2008 #5
    His subject was contradictory to his main point which was:

    Not that you need fine-tuning for a world such as ours, but that you need fine-tuning for a universe such as ours to exist.

    As to your point, it's not blind luck, but lots of time that is the key ingredient. A lot more than 20 billion years for our brane. The universe can be for a trillion billion years; thus everything can happen. No luck required.
  7. Dec 28, 2008 #6
    I was thinkig that there are many DIFFERENT branes with different worlds inside. These worlds differ in the SM paramaeters and in metrics (number of space dimensions, number of time dimensions)

    You suggest that everything can happen even on the same brane? But it requires at least 2 things:
    * SM parameters must change from time to time in the same Universe (???)
    * Entropy must be reduced (no known mechanism)

    For example, give our universe 10**100 years. It will completely burn out, leaving only elementary particles and black holes. Now you can change SM parameters, but it is TOO LATE - new stars will never form - there is nothing left.

    Anthropic principle works only if new universe is created from scratch every time, with zero entropy
  8. Dec 28, 2008 #7

    I am not suggesting that everything must happen on the same brane.
  9. Dec 28, 2008 #8
    Sorry, I did not interpret your words correctly
    But when you were saying:

    Did you mean that there is an 'external' time - BULK time? I am not sure, but it is quite probable that time is local to a brane, so different brances have different times pointing to different directions. Some brances could have >1 time or no time at all.

    Regarding the BULK, I dont know if there is something we can call 'time' there...
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