Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Life not on earth

  1. Jun 9, 2005 #1
    How can we check if there is life in outter space?
    Thankyou
    --persefone--
     
  2. jcsd
  3. Jun 9, 2005 #2

    SGT

    User Avatar

    About any form of life, probes sent to the Moon and to Mars have shown nothing. There is still hope to find some forms of life in the moons of the giant gas planets, like Titan and Europa.
    As for intelligent life, the project SETI (Search for Extraterrestrial Intelligence) has nothing to report after decades of scanning the sky. This does not mean such life does not exist, only that we are unable to detect it.
     
  4. Jun 9, 2005 #3
    I think that is just what people believe, I mean "there should be life in outter space".
    But do you know what changes in the atmosphere can help us draw some conclusions on the existence of life ?
     
  5. Jun 14, 2005 #4

    SGT

    User Avatar

    The atmospheres of the great moons are not so different of what is believed was the atmosphere of primordial Earth, so it is possible the existence of anaerobical life on those moons.
    If there was vegetal life there would be free oxygen in the atmosphere. Superior animal life needs oxygen and consequently plants or green algae to develop.
     
  6. Jun 14, 2005 #5

    Chronos

    User Avatar
    Science Advisor
    Gold Member
    2015 Award

    Let's not forget mars. While no smoking gun has been found, there are still tantalizing clues.
     
  7. Jun 14, 2005 #6

    DaveC426913

    User Avatar
    Gold Member

    If it were Earthlike vegetation, yes. We cannot assume that.
    If it is Earthlike animal life, yes. We cannot assume that.



    P.S. Be carfeul throwing around that word 'superior'. There is a pretty strong argument that simpler life forms which have done quite nicely unchanged for a billion years, are 'superior' to more complex forms that have only been around for millions our even thousands of years.
     
  8. Jun 15, 2005 #7

    SGT

    User Avatar

    The only lifeforms we know are Earthlike. If we are to detect non intelligent life at a distance, as the OP asked, we are limited to what lifeforms we know.
    I think you are being PC with my use of the word superior. What I mean by superior is complex life. Simpler forms of life can extract energy from fermentation, but this is not very efficient. To provide energy to complex forms of life we need oxidation. Even if there are other possible oxidizers, like chlorine, they are not as abundant as oxygen, so I think there must be free oxygen in the atmosphere to allow complex life.
     
  9. Jun 15, 2005 #8

    Phobos

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    (1) Missions to other planets to check first-hand (e.g., what we've been doing on Mars)
    (2) Inference from tell-tale signs as observed through telescopes (e.g., out-of-equilibrium chemistry in the atmosphere not explained by geologic processes such as all the methane in Earth's atmosphere).
    (3) Listening for signals (e.g., SETI).
    (4) Examining meteorites on Earth that may contain signs of life from their place of origin.
    (5) Checking that the folks on the ISS still have air. :smile:
     
  10. Jun 15, 2005 #9

    Phobos

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Well, they do have a few "wow" signals that would be excellent possibilities if it weren't for one critical failing...the signals were never repeated so they can't be confirmed.
     
  11. Jun 15, 2005 #10

    Ivan Seeking

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    It is much too early to draw any conclusion from SETI. We have hardly even begun to look. In fact, due to some new systems coming online, I think it was Seth Shostak who just commented that he expects success within ten years.
     
  12. Jun 16, 2005 #11
    SETI is listening on the wrong frequencies...
     
  13. Jun 16, 2005 #12
    Whose to say that life out there would need the same premises to live as we did/would? If its a completely separate development of life happening completely independantly of ours, why would it be required to follow the same design that life on Earth followed from?

    This is a very evolutionary-sounding post.
     
  14. Jun 16, 2005 #13

    SGT

    User Avatar

    Life on Earth is very successful. Since we believe that the laws of chemistry are the same in all Universe, there is no reason for life to be entirely different elsewhere. If it is we will be in great difficulty to detect it.
     
  15. Jun 17, 2005 #14

    Phobos

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    or at the wrong times...or at too blunt a detection capability
     
  16. Jun 17, 2005 #15

    Phobos

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    As noted above, it appears that the laws of physics are the same throughout the universe. Even if an alien lifeform is very different, if it is a technological one, then it should know about radio waves. And it should realize that radio waves provide one of the most effective means for interstellar communication (cheap, easy, fast, long-range, commonplace).
     
  17. Jun 17, 2005 #16

    Nereid

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Except, of course, that we Homo sap. only 'learned' about radio a century or so ago; maybe in another century, Phobos III will write: Even if an alien lifeform is very different, if it is a technological one, then it should know about neutrinos. And it should realize that neutrinos provide one of the most effective means for interstellar communication (cheap, easy, fast, long-range, commonplace).

    Maybe we just haven't 'got' it yet?
     
  18. Jun 17, 2005 #17

    Phobos

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Sure, why not.
    Of course, I'd have to disown Phobos III for such insolence. ;)
     
  19. Jun 17, 2005 #18

    Nereid

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Nah, you'll be the proudest grandparent on the planet - such insight! such originality!! :!!)
     
  20. Jul 28, 2008 #19
    just throwing this out there, but what if there are elements not known to man present on other planets that other life are able to sustain themselves on. Or did we discover all elements already?
     
  21. Jul 28, 2008 #20

    arildno

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    Dearly Missed

    The periodic table is not a fantasy. What are you getting at?

    Besides, don't be a paleontologist.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?