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Probabilities of earth like orbits, and solar systems like ours?

  1. May 3, 2005 #1

    wolram

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    What are the probabilities of earth like orbits, and solar systems like ours?
     
  2. jcsd
  3. May 3, 2005 #2
    near nonexistant in the known universe......however there is so much out there that we cannot even begin to know or see, it's all simply speculation when answering a question like this.
     
  4. May 3, 2005 #3

    ohwilleke

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    The question is too ill defined to have an answer. What defines an Earth-like orbit? That is is circular? That it is in a given range of AUs from its star? That the apparently luminosity of its star tends to be similar (within a certain range)?

    Likewise, what constitutes a solar system like ours? That it has a non-binary primary star? That it is orbited by planets? That those planets include both inner rocky planets and outer gas giants?

    I presume that the underlying question is something along the line of "how many systems can support life as we know it" and that this is a subquestion in that line of reasoning.
     
  5. May 3, 2005 #4

    wolram

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    Ohwilleke
    If you like i will try to rephrase the question , given that there is only so
    many permutations for orbits, solar system dynamics, what is the probability
    of the AP being correct
     
  6. May 3, 2005 #5

    turbo

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    I believe that the universe is infinite both temporally and spacially, although I cannot prove either. If the U is truly infinite, the AP is absolutely irrelevant. Post 17 in this thread sums up my disgust with this concept:

    https://www.physicsforums.com/showthread.php?p=532639#post532639

    If every living being (even ones that we would not consider sentient) in the present universe is entitled to claim that the Universe was fine-tuned to produce them personally or as a species, we are in pretty big trouble. Some string theorists seem enamoured of this concept. Why not? There are almost as many string theories as there are string theorists, yet none of them make solid falsifiable predictions about our Universe. Draping the Anthropic Principle over these theories may provide some hope that String (M theory) is not quite dead, but how many decades can you spend developing a theory before the funding entities ask you to make a testable prediction or two?
     
  7. May 4, 2005 #6

    wolram

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    Turbo-1
    I can not disagree with any of your post, but i was wondering how finely
    tuned "our" solar system needs to be to support life, earths distance from
    the sun and its circular orbit is one factor, but what if we did not have
    a gas giant to intercept spaces debris, etc etc.

    If our U is infinite then the possibility is that our solar systems format is not
    unique," it is just a matter of probabilities".

    The thing i am not sure about is the ingredients needed to make a sustained
    life supporting system, ie would we be here if saturn did not exist or jupiter?
     
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