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Thread: Life in the Universe and the Infinite Monkey Theorum

  1. #31
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    If every possibility is worked into the calculations for an infinite Universe, you would also have to consider the possibility that earth-life is the first and currently only patch of life in the Universe, so the probability of life elsewhere in the Universe could not be 1, but would be infinitely tending towards 1.

    The same thinking (that every possibility is possible given an infinite Universe) must then allow that we could be the first patch.

    Is there something wrong with my logic (or how I expressed it) above?

  2. #32
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    Quote Originally Posted by Spoons View Post
    If every possibility is worked into the calculations for an infinite Universe, you would also have to consider the possibility that earth-life is the first and currently only patch of life in the Universe, so the probability of life elsewhere in the Universe could not be 1, but would be infinitely tending towards 1.
    If by infinite we mean infinite in both time and space, then no, that would not be possible. There would have to have been inhabited planets (indeed, infinite numbers of inhabited planets) already. There would even be an infinite number of planets identical to our own, with the same view of the night sky.
    As above, so below

  3. #33
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    Sorry, I wasn't clear. If infinite in space but not in time then there would be a chance, however small, that we are the first inhabited planet.

    In that case would my previous post be logically sound?

  4. #34
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    Quote Originally Posted by Jens View Post
    I may be relying on old information, but I used to have a book written by a sort of non-mainstream cosmologist named Eric Lerner, that was called "the big bang never happened". And he was basically arguing, IIRC, that the big bang was sort of a "local event." And my interpretation of The History of Time is that Hawkins was arguing that space itself was created with the big bang, and didn't exist before it.
    I think Hawking is of the school that the Big Bang indeed was the very begining of the entire cosmos. At least he used to be, I'm not sure what he thinks of it now when he's reportedly fitted his model in with Steinhardt/Turok's cyclic model. It's also a very common way of phrasing things in popular science books and the like.

    However I'm pretty sure that's not quite so universally accepted as being "true" in the cosmology circles. For example Ned Wright who I don't believe to be an ATM cosmologist is apparently of a mind that the universe is spatially infinite (which it wouldn't be in Hawking AFAIK) and what we observe as the Big Bang is strictly just the initialization of our "local patch" of the universe (tho he does subsribe to the theory of simultaneous birth of the entire universe at that time):
    http://www.astro.ucla.edu/~wright/infpoint.html

    Similarly a lot of cosmological papers (of non-ATM variety I believe, well not all of them in any case) seem to be rather circumspect about the entire extend of the universe and usually refer to the remit of the theories handled being the selfsame "local patch" of which our observable universe is rather often thought to be a part of. I even found a nice diagram of the post-Big Bang event cosmis evolution once that used the term specifically but can't recall where now (I think it may have been on NASA pages somewhere).

    On the subject of infinite cosmos, my understanding is that anything that is possible to occur in such will necessarily occur. This is admittedly counterintuitive, at least to me, but maths says it's so and I guess that has to be good enough. As to if it will occur an infinite number of times, I'm not entirely sure and would have to actually think about the maths which will make my head hurt -- I'm after only a lowly computer scientist (by training, not by profession)
    The dog, the dog, he's at it again!

  5. #35
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    Quote Originally Posted by Spoons View Post
    Sorry, I wasn't clear. If infinite in space but not in time then there would be a chance, however small, that we are the first inhabited planet.

    In that case would my previous post be logically sound?
    Good question, my understanding is that in an infinite universe anything that is possible will happen, indicating an infinite number of ET civilisations, and an infinite number of identical 'earths' and so on. The concept of 'only' and, to a degree, 'first' don't sit well with this although it's counter intuitive to us to think this way. In fact, the whole notion of physical infinity is counter intuitive and that way madness lies.
    Last edited by Aik4on; 2010-Feb-25 at 07:52 AM. Reason: Syntax error

  6. #36
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    Yes, but "will happen" suggests involvement of time. At some time there will be an infinite number of planets with life, but they don't magically all spring into existence at the same time.

    Thus saying the probability of others currently existing out there is 1 would not be correct. Close enough to just call it one, but not actually one. Unless you consider time infinite too, in which case a first life-inhabited planet would have not necessarily have real meaning.

  7. #37
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    Well no because following the logic of infinity then life will have started and developed at the same rate on an infinite number of planets at the same time. As I say, pondering this is a fast track to insanity.

  8. #38
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    Well, actually, no, your explanation makes perfectly good sense. I'd overlooked that.

    Nothing insane about such musings. That said, this is coming from someone who used to frequently go shopping at the liquor store in a dressing gown. (It was a short walk)

  9. #39
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    And the thing is it doesn't really matter one way or the other.

    If the universe is infinite then we have no way of proving this, we will always be bound to the part of which we are ever able to observe. If the universe is finite again we will always be bound to what we can observe.

    Mind you never say never!

  10. #40
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    Quote Originally Posted by cosmocrazy View Post
    If the universe is infinite then we have no way of proving this, we will always be bound to the part of which we are ever able to observe. If the universe is finite again we will always be bound to what we can observe.
    Unless of course some day we discovered how to harness Wormholes or some other FTL technology. In which case we could theoretically go outside the Observable Universe and see what's there.

  11. #41
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    At that point I suppose we'd redefine the Observable Universe.

  12. #42
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    Wink

    Quote Originally Posted by Murphy View Post
    Unless of course some day we discovered how to harness Wormholes or some other FTL technology. In which case we could theoretically go outside the Observable Universe and see what's there.
    Well yes I'd thought of that one, and Spoons has basically summed it up.

  13. #43
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    Quote Originally Posted by Spoons View Post
    If every possibility is worked into the calculations for an infinite Universe, you would also have to consider the possibility that earth-life is the first and currently only patch of life in the Universe, so the probability of life elsewhere in the Universe could not be 1, but would be infinitely tending towards 1.

    The same thinking (that every possibility is possible given an infinite Universe) must then allow that we could be the first patch.

    Is there something wrong with my logic (or how I expressed it) above?
    Could be the first patch; just very unlikely. In John Leslie's book DOOM SOON, he argues that the chances of you or me being where we are in time is very unlikely if the human race ends. up populating the whole spiral---population in trillions or quadrillions. Your "patches" are infinite, what are the chances? One way Leslie points this out is if you imagine waking up in a windowless room. You know you are either in a hotel with 10 rooms, or in a hotel of a thousand similar rooms. Which hotel are you most likely in?

  14. #44
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    I don't do hotels... I'm too intense. (In tents... hey? Hey? Awful - I must sleep more.)

    I'm going to guess 10 rooms. I'll have to look up that book - sounds interesting.

  15. #45
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    Quote Originally Posted by snowcelt View Post
    Could be the first patch; just very unlikely. In John Leslie's book DOOM SOON, he argues that the chances of you or me being where we are in time is very unlikely if the human race ends. up populating the whole spiral---population in trillions or quadrillions. Your "patches" are infinite, what are the chances? One way Leslie points this out is if you imagine waking up in a windowless room. You know you are either in a hotel with 10 rooms, or in a hotel of a thousand similar rooms. Which hotel are you most likely in?
    The problem with this line of thinking is that probability doesn't work like that if infinity is involved.

    Suppose the human race ends up populating the whole galaxy...forever. If you pick a person at random, when is he most likely to be born? Within the first billion years? Within the first trillion years? Within the first quadrillion years?

    No matter what number you chose, it's an infinitesmal amount compared to forever. The naive way to look at it would be to say the probability must be zero--no matter what the age!

    That leads to the nonsensical result that no matter what person you choose, you chose a freakishly young age of the universe to chose him from.

    So, probability doesn't work in the naive way. The only probability distributions which actually make mathematical sense are ones which are non-uniform.

    Now, let's suppose that some day the human race will end, and the universe will more or less die at some point in the future. Does that make the intuitive sense of probability work again? Maybe, maybe not. We don't know whether or not there are an infinite number of possible universes out there. And why should the probabilities be restricted just to human beings? Why not aliens? Why not plants? Why not random clumps of interstellar dust?

    So basically, probability doesn't work like that.

  16. #46
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    Not to mention that chances of you, me, or Mr. Leslie being "here" (whereever that is, precisely) is almost exactly 1 and the chances of being elsewhere are almost exactly 0 (give or take the very remote possibility of some quantum physical shenaningans suddenly evidencing in macroscopic world), at least if one subscribes to the notion that a human is a material product of a material (biological) evolution operating in a material universe. You can't be anywhere else because then you quite simply wouldn't be you.

    Obviously if you are a dualist of some cloth and subscribe to that you consciousness/mind/spirit/soul has entered this moment in time and location in space (broadly speaking) from somewhere else, then it may arguably become fantastically unlikely that you should've "chosen" this specific hour to drop by.
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