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Chances of advanced life existing

  1. Nov 18, 2008 #1
    is the chances pretty rare that advanced and intelligient life exists somewhere else in our universe, I mean it seems like we got pretty lucky here on earth to get these conditions to have such abundant life. I am not doubting that bacteria and other simpler organisms exist elsewhere but it almost seems like the chances of advanced life forms is quite small.
  2. jcsd
  3. Nov 18, 2008 #2


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    It is virtually impossible to evaluate the odds with much accuracy due to the existence of only a single data point. What we do know is this:

    1. Life arose quickly on earth, but took a long time to evolve to get to us. That *may* imply that you are correct.
    2. Current detection methods are only good for finding large planets orbiting close to stars. And we've found an awful lot. What this tells us is:
    a. Most stars have planets.
    b. A substantial fraction of planetary systems - perhaps most of them - are likely incapable of supporting life.

    The combination of those facsts/inferences leaves a lot of wiggle room in our estimates of the odds. It is not inconceivable that as much as a few percent of stars could harbor intelligent life. If that is the case, there could be millions in our galaxy alone. Such a thing would not contradict our currently available data. But it is also still conceivable that it is a billion to one shot, in which case there could still be a hundred in our galaxy. I doubt many scientists believe the odds to be much lower than that, though.
  4. Nov 18, 2008 #3
    Not that it necessarily influences the likelihood of there being life elsewhere, since there are a variety of conditions such as a Europan environment it might develop in, but I remember coming across two other points in addition to Russ's:

    • That amongst the extrasolar planets we've been looking at, nearly-circular orbits like those of the Sol system are relatively rare. Most planets we can see have wildly eccentric orbits, some like those of comets in this solar system.
    • Evidently it's thought that the oceans somehow provide something like lubrication for plate tectonics? And it's speculated that plate tectonics may have something to do with the presence or maybe diversity of life on Earth.
  5. Nov 20, 2008 #4

    jim mcnamara

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    Read about the Drake Equation.
    which attempts to estimate the number of advanced communicative civilizations nearby.

    N, the number of civilizations, as Russ said, is already proven to be at least 1, and considering the incredibly immense sample size, it is very unlikely that N is truly 1,
    and it is not unreasonable at all to assume N > 1. We have no proof of this of course.
  6. Nov 30, 2008 #5
    Take a look at this article:

    Brin, Glen David. 1983. http://www.brin-l.com/downloads/silence.pdf" [Broken], Quarterly Journal of Royal Astronomical Society, 24: 283-309.

    Its an interesting and detailed discussion on the topic that I think you and many others would enjoy.
    Last edited by a moderator: May 3, 2017
  7. Jan 29, 2009 #6
    Just curious, did anyone read the article and have any thoughts on it?
  8. Jan 29, 2009 #7
    russ' point is central - even with the assumption ofthe same evolutionary dynamics brining "intelligent" life, we don't know the conditions that brought life's initiation so can't project the odds. Models and projections are sheer speculation - and there's certainly no way to validate. Points don't have slopes.

    Some may remember pompous Sagan's billions and billions argument - that there are so many chances life just has to have arisen > once. More a made for tv argument - scientifcally it fails against russ' point.
  9. Jan 29, 2009 #8
  10. Jan 29, 2009 #9
    That is absolute silliness. The so-called Drake equation is bull - no matter how many stars there are - without knowing the critical variables leading to the initiation, sustenance and evolution to intelligent life, no one can project the chances of life existing in other places, much less valdidate some silly equation to that purpose.

    Uncritical thinking of that type is the opposite of science - it is opinion. Like anuses, all have opinions, and this one is appropriately full of it.
  11. Jan 29, 2009 #10

    Andy Resnick

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    Oftentimes, I am unconvinced there is intelligent life on this planet.
  12. Jan 29, 2009 #11
    The Drake equation is not meant to be scientific, it's meant to stimulate debate on the issue. Even Scientists like to speculate on the big questions.
  13. Jan 29, 2009 #12


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    No part of this argument explains why the Drake equation itself is bull.
  14. Jan 29, 2009 #13
    It's just a statistical probability analysis...no need to get your panties in a bunch! :wink:

    The sheer number of possibilities makes it plausible. If you buy a lottery ticket, you have a slim chance of winning, however, if you buy BILLIONS of lottery tickets, you have a pretty good chance.
  15. May 8, 2009 #14
    Well intelligent life is common on earth, all animals and possible plants show some degree of intelligence but it is clear that advanced intelligence on the level that we have is rare

    Very rare, with some 3 million species on earth and possibly some 30 billion having existed in the past we are the only species that show advanced intelligence. This is odd since it seems that advanced intelligence is NOT selected for. It holds no real evolutionary advantage. If it did insects would have developed advanced intelligence millions of years ago.

    If advanced intelligence is so rare here then probably it is rare in the universe, maybe incredibly rare, just think of the chances that a star has planets capable of supporting life, then think what are the chances that life actually gets started, then what are the chances that out of billions of species one develops high enough intelligence to go interstella walk about, then what are the chances of them finding us ?
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