How rare is life in our Universe?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Seattle, Jun 18, 2018.

  1. Seattle Valued Senior Member

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    Unfortunately this is one of those questions for which there is little data (at the moment) to support whatever your viewpoint is.

    If this was a test question at school your teacher wouldn't care about the answer so much as your thinking leading up to that answer. I guess that will have to be the criteria for this thread.

    Life came about rather quickly here on Earth (single cells) but as I recall another couple of billion years passed before multi-cellular life came about and it's only been in the last 500 million years (out of 4.5 billion years) that life as we know has flourished.

    It would be very helpful if we could find evidence of any low level life in the rocks on Mars (or elsewhere within our Solar System). It would be helpful if we could create any kind of life in the laboratory.

    I'm guessing that, given the large number of planets in our Universe that simple life is not too rare. That's the biggest hurdle to overcome though. If that's the case there it's just a matter of time and numbers.

    There are many things that can end life or prevent it from developing further and we also may be rather early in our Universe for life to develop as widely as it may develop over time.

    I'm not so sure about highly intelligent/evolved/adaptable life (similar to man) being anything other than very rare.

    As far as finding an answer to this question, there's SETI-like projects. Even though intelligent life is probably very rare, it should be the easiest to detect but I don't personally have a lot of faith in SETI-like approaches. I also don't particularly think we should be trying to contact such life. It might be like trying to make friends with a wild lion...not a good idea.

    The best shot of getting more questions answered is probably from within our own Solar System. As technology improves, I think it will be possible to examine the atmosphere's of planets in other star systems to look for gases (particular isotopes) that don't usually occur without some form of life generating it.

    I guess I'm expecting low level life (multi-cellular) to be somewhat common and highly evolved life to be pretty rare for many reasons such as lack of need, natural extinction events, etc.

    What are your thoughts?
     
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  3. Hayden Registered Senior Member

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    Earth, only known life supporting planet.

    The life is found in extreme environs on earth, if we extend this observation then we are not alone. Billions of planets are there, what is conducive for life may not be exhaustively known to us, hence life in some form can be expected on other planets too.
     
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  5. Musika Last in Space Valued Senior Member

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    Anothet scope for advancing this field could be in our abilities to investigate our environment. Just as micro biology revealed an entire new world to be explored, similat game changing advancements could revolutionize how we investigate our environments. The subject matter could be right under our noses as opposed to far, far away in a distant galaxy.
     
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  7. Seattle Valued Senior Member

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    This is certainly possible as well. If we find microbes that aren't related to life as we know it (meaning non-common DNA) that would at least verify that life started from scratch more than once here on Earth.
     
  8. gebobs Registered Member

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    First off, how would one contact another civilization? Despite what the movies would have us believe, the signal from Honeymooners episodes are quite attenuated at this point. How would we get a signal to them? We can send records on probes but there's no guarantee they would eve be found.

    Second, by the time any advanced civilization got a message, understood it, decided we were an existential threat, determined where we were, and made there way here by some means, we'll probably already be gone.
     
  9. Gawdzilla Sama Valued Senior Member

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    True, without FTL drives they won't be here any time soon. With FTL drives they'd probably go somewhere interesting instead of coming here.
     
  10. Seattle Valued Senior Member

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    I think people spend too much energy thinking about advanced civilizations rather than just trying to determine if there is any type of life elsewhere. Looking for isotopes of oxygen that are generally only associated with life is much more productive, especially as the technology to do that improves.

    If simple life is very rare then there is no use focusing on "advanced civilizations".
     
  11. gebobs Registered Member

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    Concur.
     
  12. mathman Valued Senior Member

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    At present, the only way to look for life outside the solar system is to look for signals created by advanced civilizations. Hopefully in the future details of extra-solar planet finding might include evidence of life on such planets.
     
  13. Write4U Valued Senior Member

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    Given the enormous spatial and time scales found on planets throughout the universe and given that bio-chemicals are already produced in cosmic clouds from bombardment of ultra-violet radiation, the probability of ''large numbers of rare events" occurring in the known universe is still a realistic assumption.

    If we can find evidence of a second existence of life, past or present, on another planet in our solar system, the probability factor that life exists in other suitable solar systems goes up exponentially, IMO.
     
  14. Seattle Valued Senior Member

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    I agree that the law of very large numbers is the prime argument in favor of life although I don't think we can really assume very much at this point with a data set of one.

    I'm not sure what bio-chemicals are produced by ultra-violet radiation though? Care to explain?
     
  15. Write4U Valued Senior Member

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    Deleted for duplication
     
    Last edited: Jun 18, 2018
  16. Write4U Valued Senior Member

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    Robert Hazen (Chance, Necessity, and the Origins of Life) alluded to this as demonstrated by Louis Allamandola, NASA-ARC (Ames Research Center).
    https://en.wikipedia.org/wiki/Ultraviolet

    It seems to be instrumental in the self replication of polymers?
     
    Last edited: Jun 18, 2018
  17. Michael 345 Looking for Bali in Nov Valued Senior Member

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  18. Xelor Registered Senior Member

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    How rare life is in the universe seems to depend on where on is in the universe. It's obvious, based on the info we have thus far obtained, that great distances must exist between forms of sentient life that bothers to "reach out" to other lifeforms beyond those with which it shares a moon/planet. On the other hand, where sentient life such as ours is found, there's lots of it.

    Life in the sense of "something that is alive," well, there's no telling yet how much of, how abundant be, that type of life. Sure, the probabilities suggest there should be (or should have been) lots of it out there somewhere....

    A question that's crossed my mind on this topic is this: what are the probabilities that life (simple or "fancy" like humans) formed somewhere and there went extinct before it figured out how to move to a new planet/moon before the one on which it existed went "bye bye" due to one or more of the myriad life ending events celestial bodies effect? That question crosses my mind because we think "average" stars like ours last for about 10 billion years. Well, here on Earth, it's taken 4.6B years to get "us." Might life have formed around some or many of those "fast burning" stars and been snuffed out when its star exploded?
    • Take, for example, any distant star that we have observe explode. That event happened at the end of the star's life, which means any life in its solar system would have to have sent out whatever communications it was going to before that event. Well, if life did send a "shout out," we clearly "weren't home" when it "called," and it had to have been doing so hundreds of millions to billions of years before its star went kaboom. So unless that life moved to a new solar system, it's not any longer sending messages. So unless the signals are spinning around and rebounding off of things in a circular/spherical universe, it's conceivable that we're going to be around to receive them the next time they come by Earth.
    • IIRC, when stars explode, they can release gamma ray blasts. Well, those things can kill the kinds of life of which we're aware, so life near a star "gamma-exploding" could well be life that was snuffed out well before we had any chance of discovering it.
    Another consideration that strikes me is that insofar as the Sun is ~4.6Billion years old, something must be up that other stars that are about the same age, have planets, and are somewhat near us in the universe manage also not to have in about the same period formed "reach out and touch" forms of life.

    Lastly, it seems to me that it could be that life is a fairly easy thing to get started given the right conditions, but that the rare happenstance is the emergence of right conditions when solar and/or planetary systems form.
     
  19. Gawdzilla Sama Valued Senior Member

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    "It's obvious, based on the info we have thus far obtained, that great distances must exist between forms of sentient life that bothers to "reach out" to other lifeforms beyond those with which it shares a moon/planet."

    Why is it obvious?
     
  20. naturallygorg Registered Member

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    Well, extraordinary happens, especially in a big universe. There could be a possibility that a life exists. No one really knows.
     
  21. sideshowbob Sorry, wrong number. Valued Senior Member

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    I think I heard Carl Sagan say something like that. Even if the universe was teeming with sentient technological life-forms, they wouldn't come here often enough to explain all of the UFO reports.
     
  22. Gawdzilla Sama Valued Senior Member

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    What would make the trip worthwhile at all?
     
  23. sideshowbob Sorry, wrong number. Valued Senior Member

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    Bacon.
     

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