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Thread: Life in the Universe.

  1. #1 Life in the Universe. 
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    Ages ago I contributed to a thread on this topic. I said that because life could be found in very hostile environments, on our planet, I believed that life was fairly widespread, in the Milky Way Galaxy and the Universe, but that it consisted almost entirely of rather primitive life forms.
    I also said I thought other advanced technological civilisations do exist altho' I believe them to be very rare.
    Clearly I do not possess a clinching argument here, but I do feel the Earth itself is a major piece of evidence.
    But how important is the existence of our planet to this question? In other words should we be able to extrapolate from only one example? I felt this approach was criticised, possibly by DrRocket, in the previous thread mentioned at the beginning of this post.


    Last edited by Halliday; December 4th, 2012 at 01:37 PM.
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  3. #2  
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    Your statements seem to be philosophical musings. I don't see any real scientific question.


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    We can speculate - even speculate heavily with enough information, but achieve no 'answers.'

    We just don't have enough data yet for reasonable speculation. For example; We speculate about the existence of Black Holes and extra-solar planets because it's inferred by other observational data.

    The only inferred extra-terrestrial life is the magnitude of the Universe and the abundance of organic chemistry- But this inference does not demonstrate that life as we know it does exist elsewhere nor does it give us reasonable odds to work with (John Galt set me straight on this recently...)

    To quote myself from elsewhere when asked, "Is there life in the Universe?":
    But on this one, I see it a bit differently.
    The only life we know of- ok, that's true.

    But one thing we do in science is take observational evidence and extrapolate likely probabilities.
    We cannot see Dark Matter. As far as we know, there isn't any.
    But we do see the likelihood of it.

    And that's somewhat how I see this topic. I don't need to see every planet out there to say I "know" there is life elsewhere out there. In order for me to think that there isn't, there would need to be a God or a divine reason why there is life here.
    I find that idea rather absurd. I also find the idea that we're the only planet with life absurd.

    So if anyone asks me, "Is there life elsewhere in the Universe," I'm confident enough with the mathematical statistics to simply say, "Yes."
    Extrapolate from one example? No.

    But frankly, I find the idea that we're the only planet with any life in this hugely humongous enormous very big Universe to be absurd.
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    I may well have been th eone who critiqued your thesis, Halliday. I believe extrapolating from a sample size of one is foolish.

    It may be that life is a natural and inevitable consequence of chemical reactions in a wide range of environmental conditions. In our own system we may have subterranean life on Mars, life in the methane pools on Titan, the cloud tops of the gas giants, the ocean under the frozen surface of Europa. In the latter case, at least, there may even be intelligent life. I think Christian de Duve, Nobel laureate, spoke of "A universe pregnant with life". Jaques Mond, another Nobel laureat, thought life was a unique accident that would not be duplicated again.

    I would not be surprised by either situation, nor any of the possibilities in between. I do not think at this point we can know.

    We have several plausible explanations for how some of the steps towards life might be achieved, though we lack detailed descriptions for all of the steps. To make a fair assessment we need to work out how life did arise, in detail, then assess how likely each step could occur in another place and another time. I think we will one day reach that situation, but - despite the assertions of the optimists - we are not there yet.
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    i think one of the traps people fall into when discussing life in the universe is equating the extreme niches filled here on earth with the likelihood of abiogenesis happening in extreme niches elsewhere. evolving in an extreme niche is not the same as coming into being in an extreme niche.
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    Sometimes it is better not knowing than having an answer that may be wrong.
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    before we can start thinking clear about the universe we have to be clear of our own human existence.....as to what is mind,how does the mind interact with the body,if mind were find to be strict only to earth,then we can assume that only zombies can exist.and even at then how do we know if zombie exist? this takes me to what want us to talk about...
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    what are the possible claim to ufo? yeah ufo(unidentify flying object),is it that they come from our future? if so, does their make up fit into our chart of elements? if no, thoes it then mean they come from other existence being in the universe?if so,how did they get here?
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    if so, does their make up fit into our chart of elements? if no, thoes it then mean they come from other existence being in the universe?if so,how did they get here?
    seeing as we don't have a sample this is impossible to answer.
    Sometimes it is better not knowing than having an answer that may be wrong.
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    Quote Originally Posted by Chrispen Evan View Post
    evolving in an extreme niche is not the same as coming into being in an extreme niche.
    Although there is some evidence that life may have arisen in extreme niches (hydrothermal vents).
    ei incumbit probatio qui dicit, non qui negat
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    Quote Originally Posted by mathman View Post
    Your statements seem to be philosophical musings. I don't see any real scientific question.
    The question I asked, whether you believe it was a real scientific question or not, was about the merits of extrapolating from one example. Both John Galt and Neverfly gave answers to this question.
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    Quote Originally Posted by Chrispen Evan View Post
    if so, does their make up fit into our chart of elements? if no, thoes it then mean they come from other existence being in the universe?if so,how did they get here?
    seeing as we don't have a sample this is impossible to answer.
    what then is our best view of ufo?
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    Quote Originally Posted by merumario View Post
    before we can start thinking clear about the universe we have to be clear of our own human existence.....as to what is mind,how does the mind interact with the body,if mind were find to be strict only to earth,then we can assume that only zombies can exist.and even at then how do we know if zombie exist? this takes me to what want us to talk about...
    If you want to talk about "zombies" and "ufo's" why not start another thread?
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    halliday so sorry for changing your thread to somethingelse....but you invited anyways.
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    Although there is some evidence that life may have arisen in extreme niches (hydrothermal vents).
    and a realistic scenario imo. protection from extreme uv and all the food and energy you need.
    Sometimes it is better not knowing than having an answer that may be wrong.
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    Quote Originally Posted by Chrispen Evan View Post
    i think one of the traps people fall into when discussing life in the universe is equating the extreme niches filled here on earth with the likelihood of abiogenesis happening in extreme niches elsewhere. evolving in an extreme niche is not the same as coming into being in an extreme niche.
    We also need to keep in mind that the expression "extreme niche" is anthropocentric. Such conditions are only extreme from our perspective. They are optimal for the creatures that evolved in them.

    In like manner, all environments in the early Earth would be extreme from our viewpoint, yet were wholly normal, and many of them extensive, for the Earth at that time.
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    yeah,its does'nt have everything to do with the condition but wether life exist,which we can only tell by studying.....and keep studying,even our existence is a puzzle for us.
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    A trillion trillion trillion things had to be just right for life to evolve on earth. We may be alone.
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    Quote Originally Posted by Jim Colyer View Post
    A trillion trillion trillion things had to be just right for life to evolve on earth. We may be alone.
    There is nothing true about this statement.
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  20. #19  
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    "We may be alone" is correct.
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    Quote Originally Posted by John Galt View Post
    "We may be alone" is correct.
    Just barely... By technicality.

    Very well, I'll try again:
    Quote Originally Posted by Neverfly View Post
    Quote Originally Posted by Jim Colyer View Post
    A trillion trillion trillion things had to be just right for life to evolve on earth.
    There is nothing true about this statement.
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  22. #21  
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    Remember that Jim is an artist: he may have been using hyperbole. I f he wasn't then I agree the number was too large.
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  23. #22  
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    Quote Originally Posted by Halliday View Post
    Quote Originally Posted by mathman View Post
    Your statements seem to be philosophical musings. I don't see any real scientific question.
    The question I asked, whether you believe it was a real scientific question or not, was about the merits of extrapolating from one example. Both John Galt and Neverfly gave answers to this question.
    Actually we're not operating off of a sample set of 1. We're operating off of a sample set of 8 planets and a number of moons. Only one of them appears to have advanced life on it.

    We need to be careful of both kinds of mistake.

    1) - Extrapolating from a sample size of 1.

    2) - Extrapolating from a sample size of 8.


    Using a sample size of 1, a number of people in previous centuries came to the conclusion that every planet would have people on it.

    Using a sample size of 8 (and some moons), people in our century have come to the conclusion that only one planet in the whole universe has people on it.

    Clearly using a sample size of 8 is better than using a sample size of 1, but is it really so much better as to be held as proof of something?


    Quote Originally Posted by Jim Colyer View Post
    A trillion trillion trillion things had to be just right for life to evolve on earth. We may be alone.
    For life to evolve exactly as we see it, yes, a trillion trillion things would have to happen exactly how they did. For it to evolve into some form we haven't seen, the odds depend on how many possible forms there are, and how many likely environments there are.

    If life had first evolved on Mercury, it probably wouldn't be based on water and carbon. The denizens of Mercury would probably have looked upon Earth as an inhospitable wasteland, and decided to either mine it,or terraform it to suit the needs of their own physiology long, long ago, and thereby prevented us from coming to exist on Earth.

    They would have been the only life forms in our solar system. And looking at the other 7 planets, they would likely have concluded that it was impossible for life (of their type) to evolve on any planet but Mercury.
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    Quote Originally Posted by kojax View Post
    Actually we're not operating off of a sample set of 1. We're operating off of a sample set of 8 planets and a number of moons. Only one of them appears to have advanced life on it.

    We need to be careful of both kinds of mistake.

    1) - Extrapolating from a sample size of 1.

    2) - Extrapolating from a sample size of 8.


    Using a sample size of 1, a number of people in previous centuries came to the conclusion that every planet would have people on it.

    Using a sample size of 8 (and some moons), people in our century have come to the conclusion that only one planet in the whole universe has people on it.

    Clearly using a sample size of 8 is better than using a sample size of 1, but is it really so much better as to be held as proof of something?
    There are several errors in your thinking.

    1. The sample we are talking of is a sample of life. Whether we included or exclude other planetary bodies in our system we remain with a single sample of related life.
    2. Using a sample size of one some people came to the conclusion that universe was peopled (The Plurality of Words) and other reached the conclusion, based on the same data, that such corrupt thinking merited burning at the stake.
    3. I know of no serious student of exobiology who uses the apparent absence of life elsewhere in the solar system to support the notion that the Earth's life is unique.
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    yeah that it...we are seeing life with respect to ours,if it was some other planet and another form of life it would be different...and they also will make same conclusion like us.we cannot say for them,that the exist,they cannot say for us.just untill we meet...which i doubt.
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  26. #25  
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    Quote Originally Posted by John Galt View Post
    Quote Originally Posted by kojax View Post
    Actually we're not operating off of a sample set of 1. We're operating off of a sample set of 8 planets and a number of moons. Only one of them appears to have advanced life on it.

    We need to be careful of both kinds of mistake.

    1) - Extrapolating from a sample size of 1.

    2) - Extrapolating from a sample size of 8.


    Using a sample size of 1, a number of people in previous centuries came to the conclusion that every planet would have people on it.

    Using a sample size of 8 (and some moons), people in our century have come to the conclusion that only one planet in the whole universe has people on it.

    Clearly using a sample size of 8 is better than using a sample size of 1, but is it really so much better as to be held as proof of something?
    There are several errors in your thinking.

    1. The sample we are talking of is a sample of life. Whether we included or exclude other planetary bodies in our system we remain with a single sample of related life.
    That's because, if you see some random event you've never seen before, and know nothing about the odds of that event occurring, but wish to guess at the odds, guessing that the event is typical is more likely to be right than guessing that it is atypical. That's because atypical events happen less often.

    Example: I find a red and blue stone on the beach. I haven't seen one before, but I also haven't been to the beach before. Should I assume:

    A) - These stones are exceeding rare and I should go take it to a jeweler to see what it's worth?

    B) - That if I keep looking, I will find other similar stones?


    3. I know of no serious student of exobiology who uses the apparent absence of life elsewhere in the solar system to support the notion that the Earth's life is unique.
    They use the apparent absence of hospitable worlds. I'm not sure that I understand the distinction.

    Admittedly they also draw on the apparent lack of such worlds orbiting other stars beyond the Sun, so the sample size is bigger than 8. Or well, it is bigger than 8 if we assume life must evolve on a world with similar conditions to ours.

    How much bigger than 8 is this sample set? I don't know.
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    Quote Originally Posted by kojax View Post
    1. The sample we are talking of is a sample of life. Whether we included or exclude other planetary bodies in our system we remain with a single sample of related life.
    That's because, if you see some random event you've never seen before, and know nothing about the odds of that event occurring, but wish to guess at the odds, guessing that the event is typical is more likely to be right than guessing that it is atypical. That's because atypical events happen less often.

    Example: I find a red and blue stone on the beach. I haven't seen one before, but I also haven't been to the beach before. Should I assume:

    A) - These stones are exceeding rare and I should go take it to a jeweler to see what it's worth?

    B) - That if I keep looking, I will find other similar stones?

    .
    C: Make no assumptions at all. Do not guess. You are dealing with a sample size of one. You don't know.

    Quote Originally Posted by kojax View Post
    3. I know of no serious student of exobiology who uses the apparent absence of life elsewhere in the solar system to support the notion that the Earth's life is unique.
    They use the apparent absence of hospitable worlds. I'm not sure that I understand the distinction.

    Admittedly they also draw on the apparent lack of such worlds orbiting other stars beyond the Sun, so the sample size is bigger than 8. Or well, it is bigger than 8 if we assume life must evolve on a world with similar conditions to ours.

    How much bigger than 8 is this sample set? I don't know.
    Incorrect. Please tell me which exobilogists, planetologists, or astronomers, claim that there are no potentially habitable worlds? The expectation is that there are. It seems possible the Earth is the only habitable planet in the solar system, but that possible fact is not used to declare the Earth is unique in the universe.

    Where did you get the idea that there are many/any researchers claiming that a) there are no habitable worlds other than the Earth and therefore b) there is no life elsewhere in the universe? This is not what anyone is saying.
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  28. #27  
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    Quote Originally Posted by John Galt View Post
    Quote Originally Posted by kojax View Post
    1. The sample we are talking of is a sample of life. Whether we included or exclude other planetary bodies in our system we remain with a single sample of related life.
    That's because, if you see some random event you've never seen before, and know nothing about the odds of that event occurring, but wish to guess at the odds, guessing that the event is typical is more likely to be right than guessing that it is atypical. That's because atypical events happen less often.

    Example: I find a red and blue stone on the beach. I haven't seen one before, but I also haven't been to the beach before. Should I assume:

    A) - These stones are exceeding rare and I should go take it to a jeweler to see what it's worth?

    B) - That if I keep looking, I will find other similar stones?

    .
    C: Make no assumptions at all. Do not guess. You are dealing with a sample size of one. You don't know.


    So we can't assume it's uncommon. Nor that it is common. Only that a probability exists for each.



    Quote Originally Posted by kojax View Post
    3. I know of no serious student of exobiology who uses the apparent absence of life elsewhere in the solar system to support the notion that the Earth's life is unique.
    They use the apparent absence of hospitable worlds. I'm not sure that I understand the distinction.

    Admittedly they also draw on the apparent lack of such worlds orbiting other stars beyond the Sun, so the sample size is bigger than 8. Or well, it is bigger than 8 if we assume life must evolve on a world with similar conditions to ours.

    How much bigger than 8 is this sample set? I don't know.
    Incorrect. Please tell me which exobilogists, planetologists, or astronomers, claim that there are no potentially habitable worlds? The expectation is that there are. It seems possible the Earth is the only habitable planet in the solar system, but that possible fact is not used to declare the Earth is unique in the universe.

    Where did you get the idea that there are many/any researchers claiming that a) there are no habitable worlds other than the Earth and therefore b) there is no life elsewhere in the universe? This is not what anyone is saying.
    Please explain then. On what basis does anyone suggest there is no life elsewhere then? That's the only basis I have ever heard cited.

    The idea microbial life couldn't evolve elsewhere does not have an overwhelmingly strong case. However quite a many conditions would have to be met for those microbes to evolve into something complex enough to build a space ship.
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    kx000, if you have nothing relevant to contribute to the discussion, them please don't contribute.

    This is a SCIENCE forum. Are you interested in science?
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