Need a good analogy of finding life in the universe

  1. My friends who don't believe life elsewhere exists often use the argument of "Well if life exists then why haven't they found us yet?"

    The only thing I can think of to explain it to them is it would be the same as a man in a fishing boat lost at sea somewhere in the pacific ocean, only the ocean is 100million times larger.

    So you can see why it would be difficult to find someone?

    I don't think it does enough justice though :/
  2. jcsd
  3. IMO, using radio signals is not a requirement for life.

    Even in this small solar system, we can still hope to have microbes on Mars, fishes on Europa and silicon-based life on Titan. But we can hardly hope they are smart enough to find us.

    More on Fermi paradox.
  4. The fact that the majority of humans believe that we are the be all and end all of the universe, the pinnacle of evolution is really quite ignroant, considering the size of the universe... It seems much much more likely that life as intelligent and more-so do exist.

    We have only explored a glass of water out of the entire ocean in terms of how much of the universe we have explored.
  5. If the fact they haven't found us proves they don't exist, then the fact we didn't find them proves we don't exist I guess.
  6. phyzguy

    phyzguy 2,500
    Science Advisor

    You should consider the possibility that your friends are right. Enrico Fermi, a pretty smart guy, asked the same question (Fermi paradox). IMHO, the only reasonable explanation for the Fermi paradox is that intelligent life like us is very rare.
  7. So if I had a large net, threw it in the ocean and when I dragged it back to the ship and never caught a fish, we can assume that fish are very rare?
  8. phyzguy

    phyzguy 2,500
    Science Advisor

    You're missing the point. Your analogy describes you looking for the fish. The Fermi paradox question is not "Why haven't we found the aliens?" Admittedly we have only searched a small volume of the galaxy, and not very effectively. If we are looking for alien life at our level of development or less (analogous to you catching fish), then they are clearly hard to find. The Fermi Paradox question is "Why aren't they here?" We can imagine, with technology not much more advanced than we have now, spreading through the galaxy in a short time, on the order of millions of years. Since we can imagine doing it, other civilizations, if they exist, should have done it by now. Why haven't they? It's no good saying that they are inherently non-expansionist, since they don't all need to have spread through the galaxy, only one of them. Since they aren't here and we see no signs of them, the most logical answer is that they don't exist.

    The Earth has been heavily modified by the presence of life - the atmosphere has been changed dramatically, the sea is filled with life, most of the landmass is covered with life. If intelligent life were ubiquitous, the galaxy should look like the Earth, filled with life almost everywhere you look.
  9. The answer is simple, the universe is a BIG BIG BIG place and let's use this as an example. nothing can travel faster than light, so if aliens found our planet using a sophisicated telescope or something, any method they choose to contact us must be limited by c (assuming wormholes ect remains a theory).

    Now if they where even just 1000 light years, we've only had radio for 200 odd years... Our very own milky way is upto 120,000 lights years across so it could be upto 119,000 years before hearing any kind of contact.

    I hope this properly illustrates the magnitute the problem involved with "contact".
  10. :D
    T-shirt quote of the day.
  11. The number of stars and possible planets is incredibly huge,and the space that separates them is very emense.(look these numbers up) . . If life happened by chance on this planet by evolution (if you choose to go that route), . then the probability of it happening elsewhere due to mathmatical probabilty is very good simply concerning the number of planets in the universe alone,. . also consider life is tenacious, . it thrives to exist. even beyond itself as a single organism, such as the death of a parent which has ensured the existence of its protege, life "wants" to exist and to live on with desperation, . also consider the extremophiles. not only is life tenacious it is also lives in diverse environments, . . lastly, for those of your friends who oppose the life by chance happening and evolution scenario, the religious souls may consider that with the abundance of distant planets in the universe, God could have not only spread the breath of life across the universe, but also had the wisdom to put the galaxies at such a great distance so that mankind could never come in close contact with them, If a Creator God created all this, . why not?, . i'm just looking at both sides of the equation, . . either way you look at it, With the vast number of planets out there,and the tenacity of life itself to thrive and live, . the probabilities for life outside our own planet, are very good
    Last edited: Mar 3, 2013
  12. phyzguy

    phyzguy 2,500
    Science Advisor

    Read the Fermi paradox again. The question is not "Why haven't they contacted us?" The question is "Why aren't they already here?" Again, if intelligent life is ubiquitous, it should have already spread throughout the galaxy.
  13. phyzguy

    phyzguy 2,500
    Science Advisor

    I agree that the number of stars and planets is huge. I also agree that life is tenacious and tends to spread to diverse environments. This is the basis of the Fermi paradox - if intelligent life is common, it should already have spread throughout the galaxy. However, you can't argue that the probability of intelligent life existing elsewhere is good because the number of planets is large, because you have no idea how small the probability of intelligent life developing is.
  14. The rate of said "expansion" can only occur at the speed of light maximum! Sinse we are the new kids on the block compared to the age of the other galaxies. We too will be visited, and once we develop our own more advanced technology, we can go seeking ourselves.

    The amazing thing about earth is it isn't just home to people, there are millions of species here and bacteria all thriving. So life in itself isn't special, just intelligent life.

    But so special to be at a minimum of 1 in 1024 are really really amazing odds.
  15. phyzguy

    phyzguy 2,500
    Science Advisor

    Of course the rate of expansion is much less than the speed of light. That is why it would take many millions of years to spread through the galaxy, even though the galaxy is only ~100,000 light years across. But if intelligent life is ubiquitous, there should be intelligent species that started the expansion process billions of years ago, and even at an expansion speed of .001*c, it would only take 100 million years to fill the galaxy, and they should have arrived long ago.
  16. You're basing that off our galaxy, there's a chance that we are infact the only life in our entire galaxy, still another 500billion - 1trillion galaxies to explore. Even if 0.1% of all the galaxies in the universe has life that's still 1,000,000,000 extraterrestrial life forms.

    Even if 0.0001% of those 1billion extraterrestrial life forms is what we would call intelligent, that's still 1000 intelligent life forms in the universe.1

    1All figures taken from quick google searching. (No yahoo answers though)
  17. First the post said "life" and not "intelligent life", and the possibility of just that is greater anyway ( depending on definition of intellegent, and one could make that point moot anyway), . . second of all concerning the paradox, for life to migrate it would need to adapt and change to its environment drastically and suddenly, In space there are very few elements for survival, slowing the timeline for expansion greatly, . or the so called life would have to be intelligent to do so, (as we would travel to distant planets), . . the first scenario would be for a simple organism to either adapt a way to leave its own planet and travel on its own through space somehow, or to be ejected from such an event as meteor impact and be put into frozen suspension, . a theory which is already being explored, . the second possibility is for a complex organism which would require it sustaining itself long enough with its own biological energy needs or to hibernate while traversing these great distances,(and these are very great distances) . not only do these organisms require time to evolve to the state of a complex organism with sentient capabilities to do so, but also there is more historical timeline needed to travel these great distances, I think we as universal life are to young for that,(give it time) .not only that, but if we look at extremophile we must understand that other complex sentient liveforms may not even perceive or live in the universe as we do with our limited understanding and five senses, and communication to them may be even as of now be undetectable or completely unknown to us looking at all these evolution theories and how young our universe really is, . i see no paradox, just simply an underdeveloped universe. personally "myself", . i believe the universe is teaming with "life" literally, and the universe may even be able to be classified as a living organism itself, if one can grasp the definition, ., . .as for the probability of life, (yes i was stretcing it here, good call) and that is an interesting and good question, i wonder of we could answer that probability to some extent knowing the number of elements in the universe with also the known number of planets, etc., the hypothetical probability of of any one single life form none or unknown, being created, , .. . but like i also said, . i think man and his ego, tends to think in restricted terms anyway in thinking what a life form is made up of: molecular, carbon based, whatever, . . . as i said, . life is tenacious, just to exist in and of itself, .
  18. rather messy it think, . ergo, . . the universe is teaming with life, .. the universe is to young and distances are to great for lifeforms to have become so prolific as to reach a total saturation point among lifeforms,it takes time to overcome obstacles such as meeting biological energy needs (food etc), propulsion research ,political sidetraking, stopping universal expansion to terraform mine etc. (not enough time in the life of the universe yet, not a paradox). . and lastly, the universe itself may be a symbiotic eclectic life form of its own designation with its own sentience
    Last edited: Mar 3, 2013
  19. Exactly, us humans are the be all and end all, if we can't do it, it simply can't be done. We can't live without oxygen, so neither can anything else. We need to drink water, and sinse there are no planets with water, life can't possibly exist.

    People need to stop being so arrogant and awaken to the possibility that we are not the kings of the universe. The thought that humans are not at the top of the chain really makes us feel vulnerable, so we simply deny it.
  20. phyzguy

    phyzguy 2,500
    Science Advisor

    But you just made up those numbers. You have no idea whether those numbers are 0.1% and .0001% or 10^-20 and 10^-50.
  21. phyzguy

    phyzguy 2,500
    Science Advisor

    I agree that the Fermi paradox only applies to intelligent life. Lower life forms would appear to be unable to spread beyond a single star.
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