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Likelyhood of Extraterrestrial Intelligence

  1. Mar 18, 2003 #1
    On first glance, it seems as though the universe is so big there simply must be other life out there. And that may be the case. But is it possible that life is as common as portrayed in the scifis?

    Most likely, the answer is no. The truth is, if life were that common, it would be plainly visible. It doesn't take a huge knowledge of statistics to understand.

    If an extraterrestrial civilization had existed before us, they should have had something close to half the galaxy's lifetime to collonize it. Collonizing the galaxy seems like a monumental task, especially when you take into account that it is unlikely superluminal velocity is possible. However, in comparison to the age of the galaxy, its size is quite small. It's easy to forget that the galaxy has rotated several times (at much slower than lightspeed) since life got started on EARTH. It's rotated once since the dinosaurs.

    So if one extraterrestrial intelligence had existed before us, they had plenty of time to collonize the galaxy. And if they had done so, we would see something. Structure in the galaxy. Mined stars. Artifacts. Radio signals.

    Does this mean there is no extraterrestrial intelligence? No. But it does mean it is almost certainly rare. Unless by some freak of coincidence another intellligent race emmerged within a few million years of ours, we are the only intelligent race in our galaxy.

    If extraterrestrial intelligence exists, there are two options. They exist in distant galaxies, or they exist in the future.

    On a sidenote, it at least seems highly unlikely that only 1 intelligent race would ever form in our galaxy, considering how long it has left to live. A likely time for another one to pop up would be somewhere around twice the age of the present Milky Way's age, assuming intelligent races pop up on a regular basis.

    Any thoughts?
  2. jcsd
  3. Mar 18, 2003 #2
    Self-organization (complexity theory?) argues for intelligent alien life.

    Self-organization derives from positive feedback under constraint.

    Gas clouds contract under self gravity (+ve feedback as density increases).

    Initial random rotation leads to spin by conservation of momentum.

    Spin leads to disks.

    Disks lead to rings.

    Rings lead to planets.

    Thus most stars may have planets.

    Co-operative positive feedbacks of self-catalytic loops of co-operating reactions lead to selective reproduction of certain catalytic molecules (+ve fbk).

    Reproduction with limited resources leads to competition.

    Competition leads to evolution.

    Evolution leads to better self-oganization and co-operation.

    Thus life will start as soon as there is a viable pathway, and evolve to fill all ecological niches. (As we see in cases of parallel evolution).

    Intelligence is a competitive advantage, thus will be adopted by life if there is a viable pathway.

    The parallel evolver does not need to know anything about the original or even be on the same planet.

    Thus a percentage of planets probably hold life, and some intelligent life.

    Why haven't we heard from them?

    Perhaps someone somewhere invented computers which led to AI, which out-competed its creators and became inimical to life.

    We'll probably know soon enough as the volume of the sphere of our detectable radio emissions (and thus the number of stars able to discover us) is increasing with the cube of time.

    Sorry, I've had a few beers, I'm sure there's a better explanation.

  4. Mar 18, 2003 #3
    Suppose intelligence doesn't necessarily imply science? Maybe they all write poetry and couldn't care less about galactic colonization and radio astronomy.

    Somehow that seems worse to me than being alone in the galaxy... :wink:
  5. Mar 18, 2003 #4


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    If most of what we know about science is even remotely accurate, then this is not correct. With current technology we could not even detect life 100ly away unless they are actively transmitting something we can receive. And through passive detection, we couldn't even find life 10ly away. We don't yet have the ability to even locate earth sized planets anywhere outside the solar system, much less analyze one.

    Our galaxy is roughly 150,000 ly in diameter. There could be THOUSANDS of planets with human level life/technology and we won't know it.

    There are a couple of problems with this. For starters the technology you describe is not even theoretically possible: Interstellar travel will likely not ever be possible for anyone.

    Second, time isn't as wide open as you think: planets with life require second or third generation stars because the ingredients for (solid) planets and life didn't exist in the early universe: they were created in supernovas. So even though the universe is about 15 billion years old, earthlike planets have likely only existed for about the past 5. It also takes a few billion years for the planet to cool enough for life to arise. Then a few billion more for life to evolve. Altogether, intelligent life has probably only been possible in the galaxy for the past billion years.

    Also there is the issue of concurrence: It can't be assumed that any life that has ever existed still exists. Hell, many people still think humans will destroy themselves within the next 100 years. Thousands of intelligent species could have lived and died and there is virtually no chance we will ever know about it.

    Given all of the statistical analysis I have seen, I think it is possible, even likely that there is other life out there. Intelligent life. But there would need to be THOUSANDS of civilizations existing today for us to even have a chace to find ONE. Despite all of that, I think in the next 20-30 years we WILL find one.
  6. Mar 18, 2003 #5
    Yes, I agree with you! Dirac once said the following:

    "In science one tries to tell people, in such a way as to be understood by everyone, something that no one ever knew before. But in poetry, it's the exact opposite."

    Lately I've been thinking that what Dirac said about poetry is true about all art. It seems to me that art is basically just intellectual obfuscation and mental masturbation. Hence the reason it needs to seduce or manipulate our emotions. So for me, an intelligent lifeform that didn't pursue science, but instead pursued some artistic goal, would be a very sad thing. Solipsism of the worst kind.

    I think ETs are rare, but the universe is also pretty large. I also think that carbon chemistry need not be the only possibility for self-aware structures. Unfortunately, my imagination is far too limited to dream up alternatives to it.
  7. Mar 18, 2003 #6


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    Couple of things;

    I think its already been pointed out that Interstellar travel just might be to difficult or resource consuming for anyone to have achieved.

    Another Possibility is the Intelligence turns out to be, in the vast majority of cases, an evolutionary dead-end. That very very few intelligent races survive long enough to develop high-end technology.

    Or that upon reaching a certain level, they slip back to a lower level. (A hole that they won't be able to pull themselves out of, because the previous technological society has already used up the easily obtainable resources on their world. )

    The universe could be full of low-technology races, and maybe only one or two higher-end technology races per galaxy.
  8. Mar 18, 2003 #7


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    I'll go one step further: An intelligent life form that does not pursue science is an oxymoron.
  9. Mar 18, 2003 #8


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    And given the importance of science on this planet, shortly a dead oxymoron.
  10. Mar 18, 2003 #9
    Also, Michio Kaku once pointed out (in "Journey through the tenth dimension) that the probability of intelligent creatures evolving somewhere else is rather high - but that they would soon discover Uranium, and the probability then becomes extremely high that they would destroy themselves.
  11. Mar 18, 2003 #10
    Agreed. If only more of our own species saw this.
  12. Mar 18, 2003 #11
    As I posted elsewhere previously: remember your statistics - just one incidence of life's origin does not carry any significance toward the probability of other, similar occurences.
  13. Mar 18, 2003 #12


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    I agree with you for the most part, and have made jokes about extrapolating from a single point, but there are some "single instances" with notable impact. The observation of evolution on our one planet is telling. It is not a single point of statistics, it is an observation of the nature of life. I don't think it is unreasonable to assume a high likelyhood that if life exists elsewhere, it will evolve. It is a bit of a jump though to assume that evolution leads to intelligence. It has only been recently that intelligence has proven very useful to life.

    I think the biggest flaw in CJames theory is that a civilization would colonize the galaxy just because it could. We are primitive compared to such a civilization, and yet we have begun to develop non-interference philosophies regarding wildlife studies and anthropology. If a civilization learned to satisfy all of its wants before developing interstellar travel, it could plausibly develop the same ideals, applicable on a galactic scale. Assume one civilization is particularly precocious. It then monitors the galaxy with a light touch, preventing latecomers from "despoiling" other planets. I would imagine that would be our own philosophy...after we despoiled a few dozen planets first.

  14. Mar 18, 2003 #13
    Excellent arguments by everybody. Let's see how badly I can defend my "theory." (It's not actually mine. Idea's been around for a while. And it's not a theory.)

    First, let me reitorate my point. I hadn't said there is no other intelligent species in the universe. I said intelligent life is rare or nonexistant.

    It is certainly theoretically possible. As you have said, the galaxy is 150,000 lightyears across. That means an absolute bare minimum of 75,000 years allowed to collonize the galaxy. Obviously, that is ridiculous. However, limited to an expansion rate of .01c, for a civilization that first formed on the outer rim of the galaxy, that means 15 million years to collonize the galaxy. So, it is easy to establish that it is at least possible by this time.

    I agree entirely. As I said, my point was that we are probably the only intelligent species in our galaxy at this time.

    This is a very good point. Considering population growth, however, I would imagine any intelligent species would be scrambling for the nearest planet as fast as possible. If there is another intelligent species in the galaxy, it has either learned to slow it's population growth, or has am extremely slow population growth. (Perhaps living in a different life-expectancey.)

    Take care everybody.
  15. Mar 18, 2003 #14
    I think you're confusing wisdom with intelligence. Beethoven's Ninth Symphony was clearly created by an intelligent mind. A life form which did nothing of note except create equivalents of Beethoven's Ninth Symphony would be intelligent, but not very wise.

    Don't get me wrong, though. I'm often moved by a great work of art. But to what end? It's mostly my emotions that are affected. As for what intellectual content there is, and there's usually very little of it, I find myself asking, "It took him 500 pages to say that humans are contradictory beings?"
  16. Mar 18, 2003 #15
    Yes, I get very frustrated with "intellectuals" who talk a great deal but end up saying practically nothing. I like it clear, concise, and straightforward; to some extent, that's why I enjoy the sciences.
  17. Mar 19, 2003 #16


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    Thats fine, but I think the two go together. The brain power associated with the writing of Beethoven's Ninth is similar to the brain power associated with figuring out relativity. Its just brain power applied in a different direction. Intellectual art.

    There *IS* a lot of art that is not intellectual though. I tend to think most painging and sculpture it that way. Van Gough for example made some great paintings, but he was certifiably insane. Modern art is even worse. You can sneeze on a piece of paper and sell it.

    And since I am of the opinion that "good" art is intellectual, not purely creative, I think an intelligent species will create both intellectual art and science. One that creates purely creative art is not intelligent and it will reflect in the art.
  18. Mar 19, 2003 #17
    The reason I assume intelligent life would seek to collonize the galaxy is because of the nature of intelligence. Intelligence arises from a curiosity to know things. It is my assumption, and yes it is an assumption, that this curiousity would be a major factor in the desire to collonize the galaxy.
  19. Mar 20, 2003 #18
    all I can say is hopefully curiosity won't kill the cat if we go explore other galaxies someday. Haha

    But on a more serious matter I think that what you said (the part about how curiosity could possibly lead to the colonizaatino of galaxies) is correct, CJames
  20. Mar 21, 2003 #19
    Don't forget about mass extictions due to asteroids and comets (if not dying stars). They happen roughly every 50-100 million years on Earth, most recent 65 million years ago with the Dinosaurs. Who knows if any other civilization has even gotten the time to develop the technology needed to colonize outside of their home planet.
  21. Mar 21, 2003 #20


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    Greetings !

    My very rough SWAG for the MW galaxy :

    About 200 * 10^9 stars in the MW.

    - double/tripple and so on...
    - galaxy core
    - probably - stars with low or high metalicity (leaving
    mostly the central galactic radius range)
    - stars that are too massive and produce
    a great deal of UV radiation
    - very "light" and cool stars

    = let's say 10 - 20 * 10^9 stars.

    - stars that are aged over 2-3 billion years
    - stars that do not have planets in the
    habitable zone around the star (allowing for
    liquid water ) or gas giants that allow
    water on their moons (example: Europa)
    - planets that do not have the appropriate
    materials to form a solid core and a stable
    surface and materials to result in creation of
    large water masses

    = let's say 10 - 20 * 10^6 stars and about
    a 10% addition for planets

    - planets where living cells haven't formed

    = let's say (and this is beggining to be very
    tricky to estimate) about a half remains

    - no complex life forms evolved or they were
    destroyed by asteroids/high radiation events/
    collisions with other star-systems/system
    star's life span ends

    = (very very tricky) a complete SWAG - 50,000

    - planets where complex life formed but no
    "intellegent" life on our level, at least (There is
    a great argument about this part, I believe.
    Are we a natural stage or a fluke ?)

    = unbelievable SWAG : 500

    How was I ?

    "Does dice play God ?"

    Live long and prosper.
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