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Extraterrestrial life

  1. Feb 28, 2005 #1
    well, these days, there is a special interest in searching for extraterrestrial life

    but i dont understand this. all such missions are aimed at looking for earth like conditions,(presence of water, requisite atmospheric conditions). how can we be so sure that life can survive only in these sort of conditions.

    i mean, just think, it is possible that some forms of life may survive and flourish even(in fact, only) in conditions which we are assuming to be too harsh for life to exist.

    just imagine, some day, some extraterrestrial form of life lands on earth and after taking a look around, declares that this planet cannot posses life. :uhh:
  2. jcsd
  3. Feb 28, 2005 #2
    i got this idea from a science fiction story, where the conditions on earth become so bad that humans have to evacuate it and go to some other place. just as they leave, a spacecraft lands on earth. a creature comes out of it and says, YES, this is the sort of place which is fit for living.
  4. Feb 28, 2005 #3


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    Staff: Mentor

    These assumptions are based on chemistry, mostly. First, its thought that life must be carbon-based because of carbon's unique ability to form extremely complex molecules. Next, its thought that liquid water must be present because water is an outstanding solvent and provides a good medium for chemical reactions to occur in. There are other candidates, such as liquid methand, but its difficult to concieve of how life could form in it - so partially, its just that we're sticking with what we know.
  5. Feb 28, 2005 #4
    Well it's not nessecarily true that only Earth-like conditions will result in life but if precedence is anything it seems to work rather well on Earth. I mean if you go anywhere on this planet, practically, you'll find life (even in places not really expected). So if we find Earthlike conditions it's a good indicator, and when the universe is so huge it's nice to have a good indicator as to where to start.
  6. Feb 28, 2005 #5
    which book was that? sounds like a cool idea.
  7. Feb 28, 2005 #6
    The planet has enough to worry about. Climate change and all. If we can make this planet better then search should start again but there again looking for other planets like this one could solve problems, in a way.

    The Bob (2004 ©)
  8. Mar 1, 2005 #7
    it was not a book, just a small science fiction story publuished in a monthly magazine
  9. Mar 1, 2005 #8


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    Exploring the universe is expensive. So you go with the best bets. You could take your finite funding and spread it out to search for every conceiveable thing (thereby reducing the changes of finding anything) or focus your resources on the areas most likely to pay off.

    Liquid water is the key thing being searched for because we know how important a role that plays for life here on Earth.

    Specific atmospheric conditions are not nearly so critical, especially since we know Earthly life can inhabit such a broad range of conditions (aerobic/anaerobic, acidic/alkaline, high/low pressure, high/low temperature, light/dark, etc.).
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