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Life out there

  1. Jul 29, 2004 #1
    Can anyone work out the probabality of intelligent life at around our current level exisiting within our galaxy.
     
  2. jcsd
  3. Jul 29, 2004 #2
    I recall reading something a few years ago on the subject. I don't remember the person that did the calculations, but, those estimates determined that about 50,000 other planets (in our galaxy) should support organic life that has evolved to the point we have.
     
  4. Jul 29, 2004 #3

    Nereid

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    There are a number of PF threads - both current and in the archives - that discuss the many such calculations. Try googling on "Drake equation" for sites.
     
  5. Jul 29, 2004 #4
    "The probability"

    The probability, might be, it is everywhere. It boils down to, where the center of the universe is? If our universe was once a singularity, where are we? We are at the center and so is every other point. Its a question of time frames. All points are the same points, at light speed. If this is so, then only when are tecknology reaches, the ability to travel at subluminal speeds will we make contact. All intellegent life, would develope together simultaniously but thats only if my therory is correct. :smile:
     
    Last edited: Jul 29, 2004
  6. Jul 29, 2004 #5
    hello, well bozo, i think there were people who thought just like you. There is one guy, and he formed an equation to figure out the probability of life existing in space. you can go here (http://www.pbs.org/lifebeyondearth/listening/drake.html) and check the chances by yourself. hope it helps. ;]
     
  7. Jul 30, 2004 #6
    There is about 1 in a trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion chance (I'm exaggerating) that life is exists in our galaxy, outside of Earth. Seeing that about 90% of the galaxy is to chaotic for relatively consistant environments to form or lacks the right elements. You also need a large gas giant in the star system and a large moon orbiting a planet (large moons are super rare) to stabilize it and block asteriods. Along with supernovae sterilizing chunks of galaxies its very doughtful that life exists anywhere in the universe outside of Earth. Sorry but to me aliens are just as ridiculous as fieries, ghosts or leprechauns.

    Then again, it did turn out that leprechaun exist... :wink:

    The Drake equation is horrible incomplete.
     
  8. Jul 30, 2004 #7

    Chronos

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    Good question and good arguments against the drake premise. Personally, I think extraterrestrial life is virtually certain [I have, however, been known to be wrong]. It pretty much boils down to this

    1] Assuming our sun is a fairly common star in this galaxy (it is), some of the others have planets orbiting around them.

    2] Some of those planets are similar to earth in composition.

    3] Some earth-like planets have orbits similar to earth.

    4] Life will arise on some of those planets.

    5] Intelligent life similar to our own will arise on some of those planets.

    Assign probabilities to each and you get a non-zero probability that beings such as us have/do/will exist in this galaxy [not to mention the trillion other galaxies in the observable universe]. Whether enough of them exist, are near enough, and can be detected / communicated with at any given time is the most improbable scenario.

    I think Dr. Drakes premises are very reasonable. The principle of mediocrity suggests we are not the crown gem of the universe.
     
    Last edited: Jul 30, 2004
  9. Jul 30, 2004 #8
    Always all calculations either in favor or against the existence of extraterrestrial intelligent life, uses the assumption that life has its origins the same as we know it here on Earth. That to me is a very logical assumption and would get a vote from Occams Razor. That assumption is based on evidence from one planet ours. If we find one day life, right handed amino acids, different numeral combinations of amino acids that produce life forms, we would then draw the conclusion that, life is not unique to the parameters in which it had its origin, here on Earth and all the data we use to try and calculate its probbilities would be useless.
     
  10. Jul 30, 2004 #9

    marcus

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    Fermi's question
     
  11. Jul 30, 2004 #10
    I always find these ideas of predicting life [ala Drake] laughably primitive and simple-

    there is always this core error of assuming carbon-based biology- it's silly- I think this is assumed because carbon-based biology is the only biology we can be sure about- but the biology isn't as important as the basic dynamics of living systems which only require an adaptable and sustainable energy handling capability and an environment that contains energy-

    when one examines the tremendous complexity and specificity of conditions required for heavy-element based life and then compares it to the almost automatic and universal life-like dynamics of say- plasmas [ http://www.newscientist.com/news/news.jsp?id=ns99994174 ] it is clear that we are probably in a very tiny minority of living systems in the universe- with most life living on the surface of- or inside- stars- and in the intersteller medium and in/around nebulae-

    we just don't know enough to use something like the Drake equation- especially considering that several of it's variables mistakenly require counts of planets and requirements of carbon biology- when most life may need neither- but every day we find reason to believe that life arises from a multitude of processes/substrates- many of which are far more abundant in the universe than planets and organic compounds-

    same thing for the assumptions of the Anthropic Principle- life is going to evolve where it can with what it's got to work with- all a universe has to have is something to allow maleable/adaptable seperations and connections for the flow of energy-

    I mean like- didn't anyone watch the Andromeda Strain? :biggrin:

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    Last edited: Jul 30, 2004
  12. Jul 30, 2004 #11
    One of the assumptions behind the Drake equation is that no interstellar colonization ever occurs, by anyone. That's way implausible.
     
  13. Jul 30, 2004 #12
    Don't you mean *read* the Andromeda Strain..?
     
  14. Jul 30, 2004 #13

    Chronos

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  15. Jul 30, 2004 #14
    Actually no. We don't have a clue how most of the processes/substrates of life as we know it arose.

    Life can only evolve where it can arise.
     
  16. Jul 30, 2004 #15
    no because the book sucks- but the film is quite lovely indeed! the book is pretty mediocre and not well written- but the film experiments with cinematography/score/script in very effective and important ways

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  17. Jul 30, 2004 #16

    Nereid

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    I thought the film was way too cavalier with the science (more a problem of the medium, not the director per se), and the book much, much better in that regard. Of course, film is a far better medium for characterisation, plot, visual experience, etc.
     
  18. Jul 30, 2004 #17
    I've never seen the movie, but I did quite like the book.
    I've always found it irresponsible to make films, but that's totally irrelevant...
     
  19. Jul 30, 2004 #18

    Nereid

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    Nice vignette of the problems of doing science here. :smile:

    The Drake approach (ditto Fermi's question) explicitly assume 'life like us', and to fault it because it ignores entirely different (potential) kinds of life is like saying that economics can't tell you anything about nuclear reactions in the core of the Sun - it's way outside its intended domain of applicability. Ditto the anthropic principle (tho' for different reasons).

    How can we go about estimating – even to 5 OOM! – the probability of ‘life-not-like-us’? Based on solid science please, not unbridled speculation.
     
  20. Jul 31, 2004 #19

    turbo

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    We have (right here on Earth) life that is carbon-based, but very unlike us. For instance there are fast-growing dense populations of animals (huge tube worms, mollusks, crabs, etc) that are totally dependent on the sulfur-rich columns of water spewing from volcanic vents on the ocean bottom. If those animals were sentient and developed their own version of the anthropic principal, they would say that the universe could not have developed without providing for their existence, including a very cold, dark, high-pressure aquatic environment with lots of sulfur and no competition from light-loving photosynthesis-exploiting organisms.

    Of course, we know that such a "sulfurphilic" principal would be ludicrous, and that those creatures developed incrementally and adapted to fit their very strange environment. I have a huge problem with the anthropic principle for this very reason. Knowing what we know about the adaptability and variety of life on earth, it would be foolish to rule out the possibility that organisms have evolved to exploit the energy-gradients and "food sources" that exist in the atmospheres of gas-giant planets, on the surfaces of volcanically active moons, in partially frozen hydrocarbon lakes, etc. The organisms need only manage to exist and propogate, and they needn't be carbon-based, either. I know of NO way to calculate the probability that such organisms exist, but since there are living things all over the Earth in even the most hostile, forbidding (to humans, that is) environments, we should be open to the possibility that environments which would kill us instantly can support life - just not human life.
     
    Last edited: Jul 31, 2004
  21. Jul 31, 2004 #20
    Why? We don't say that life developed on land just because we live on it. We predict where life will occur by using our knowledge of the universe.

    Its not that simple. Life must also be able to "arise" there. Make a controlled environment with a hydrocabon puddle or a simulation of Jupiter's atmosphere (wind, lightning and all) and life doesn't form. Just because they can survive there doesn't mean a second genesis will occur.
     
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