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A Poll

  1. Jun 11, 2005 #1
    Here is a poll...how many alien civilizations do you think are existing in the Milky Way at this moment.

    - 1
    - 10
    - 50
    - 100
    - 1000
    - 10 000 or more

    I would vote for 50
     
  2. jcsd
  3. Jun 11, 2005 #2
    What do you consider to be a 'civilization'? Would a colony of alien insect type animals, eg ants, be considered?

    If you mean some orgainised life form, I'll vote for 10 000 or more. However if you mean civilizations capable of transmitting electromagnetic radiations, I'm down nearer 1.
     
  4. Jun 11, 2005 #3
    Including microorganisms, I would say 10 000 or more. If you mean like animals on our planet excluding us, I would say around 1000-10000. If you mean intelligent life, capable of using tools and etc...I would say maybe 5-50.

    Either that, or multiply my answers each by 1000 :P

    I like this quote from Michio Kaku
    "You know; when I look at the night sky and I see this enormous splendor of stars and galaxies, I sometimes ask the question, well how many worlds are we talking about? Well do the math, there are about 100 billion galaxies that are in the visible universe and each galaxy in turn contains about 100 billion stars, you multiply and you get about ten billion trillion stars. Well I think it is the height of arrogance to believe that we are alone in the universe, my attitude is that the universe is teaming, teaming with different kinds of life forms" -Michio Kaku
     
  5. Jun 11, 2005 #4
    Perhaps you can search for the 'Drakes Equation' on the web, it will give you the correct figures. Though the DE looks a bit vague , still you can rely for some good amount on it.
     
  6. Jun 11, 2005 #5

    SpaceTiger

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    Why is 0 not an option?
     
  7. Jun 11, 2005 #6

    JamesU

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    why don't you actually add a poll to this poll thread?
     
  8. Jun 11, 2005 #7
    SpaceTiger, you think its just us in this whole galaxy?

    And yeah I meant civilization as in some kind of technological species.
     
  9. Jun 11, 2005 #8

    tony873004

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    What defines technological species? If we found a civilization on another planet that were identical to humans 1000 years ago would that count? No electronics, ect. They had invented the wheel, and a lot of other useful things, but not things we today consider technology.

    As far as simple life, I would guess it's all over the place. Look at how well it adapts on Earth. If I don't take my laundry out of the machine for 2 days, it stinks of mold. If I don't weed my garden every few weeks, it becomes overgrown. Grass grows from the cracks in the sidewalk, green stuff grows on my shower walls. The Galileo Spacecraft sent to Jupiter, even after existing over a decade in a vacuum with no protection from radiation needed to be crashed into Jupiter to avoid contanimating Europa with life.

    Earth's biosphere is flooded with life, from deep below the surface to nearly the top of the atmosphere.

    It's difficult to imagine that all other planets would have the opposite problem.
     
  10. Jun 11, 2005 #9
    The drake equation is meaningless. It's completely arbitrary with a margin of error through the roof.

    I vote 1 in this galaxy, and 1000+ in the universe.
     
  11. Jun 11, 2005 #10

    turbo

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    Good points, Tony. Life on Earth is incredibly tenacious. Try to get rid of a termite infestation or fire ant colonies in the Southern US, and you'll get a feel for the kind of firepower (poisons, denial of habitat) that it entails. I would not want to live in a house that had been tented and saturated with poisons to kill termites! I live in the frigid north (in Maine) and even with the long sub-zero winters, organisms manage to adapt and thrive. We have molds, spores, aquatic organism infestations (red tide is currently crippling the clamming/mussel trade), and invasive water plants, etc, that are seemingly impossible to defend against or even moderate slightly. Every ecological niche that can be expoited is exploited. If Earth is any example, life that arises anywhere will conform and adapt to diversities and it will survive anything less than a planetary catastrophe. I am rather optimistic about the existence of extraterrestrial life, although the survival value of intelligence is a huge wild card. Intelligence gives humans lots of advantages in learned behavior and adaptability, but cockroaches currently hold the gold medal in species longevity, and they may have the last laugh.
     
    Last edited: Jun 11, 2005
  12. Jun 12, 2005 #11
    I consider it to be a civilization when the creatures learn to write or otherwise store information so they can keep historical records. I'd vote for 10 in that case (just a wild guess).
     
  13. Jun 12, 2005 #12
    That's funny because it is estimated that there are 100 billion galaxies, so howcome this galaxy would be special and have two species when barely any others would?
     
  14. Jun 12, 2005 #13

    Chronos

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    This is a pure crap shoot. I agree with SpaceTiger based on current observational evidence - we may be alone in this galaxy. I think it is possible we are among the first sentients to arise in this galaxy. The universe has a violent and hostile [to life] history - supernovae, gamma bursters, planet busting collisions, etc. It is conceivable conditions permitting beings such as ourselves to evolve were extraordinarily rare up until a few billion years ago.
     
  15. Jun 12, 2005 #14
    Wow, I was expecting Chronos to post...at least 50.
     
  16. Jun 12, 2005 #15

    saltydog

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    Can't resist. Know about Drake's? I got one I call Salty's: N=2. Simple: Life is massively contingent and there are plenty of stars in the Milky Way. These terms cancel leaving unity. I added one because I'm optimistic.

    Salty
     
  17. Jun 13, 2005 #16
    Chronos, I mean there are 200-400 billion stars in the Milky Way, even you said it your self...most stars have planets and gas giants could also have habitable moons, just by the sheer amount of that, I REALLY REALLY think there are about 50+ intelligent civilizations in the Milky Way existing right now.

    Also, I sent you a PM.

    PS: I also want to know what SpaceTiger has got to say on this matter.
     
  18. Jun 14, 2005 #17

    Chronos

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    SpaceTiger already voted for zero, and I think I know why.
     
  19. Jun 14, 2005 #18
    Oh crap, two of the smartest voted for 0 and 5-10, and here I am saying at least 50.

    Chronos, are you saying that the average galaxy will produce about 100 alien civilizations in total?, really man the number seems really really small to me.
     
    Last edited: Jun 14, 2005
  20. Jun 14, 2005 #19
    While it is correctly classified as speculation, it is reasonable and informed speculation that lies behind the "rare earth" hypothesis. Although I would really very much like to be wrong, I would have to put my money on zero technological civilizations (besides us) in the Milky Way.

    To quote one review (The Library Journal) of the text by Peter Ward and David Brownlee:

    "Ward and Brownlee attribute Earth's evolutionary achievements to the following critical factors: our optimal distance from the sun, the positive effects of the moon's gravity on our climate, plate tectonics and continental drift, the right types of metals and elements, ample liquid water, maintainance of the correct amount of internal heat to keep surface temperatures within a habitable range, and a gaseous planet the size of Jupiter to shield Earth from catastrophic meteoric bombardment."
     
  21. Jun 14, 2005 #20
    I think Rare Earth is too pessimistic, I heard one of the authors was a creationist?, I dont think intelligent life is abundant but I also dont think its just us though.
     
  22. Jun 14, 2005 #21
    Hi GB,

    No neither author is a creationist, they are in fact two very respected scientists as I have gathered. Ward is a paleontologist and Brownlee an astronomer (errata: it is not David but Donald Brownlee that I was referring to). One of their arguments was informed by conversations with Guillermo Gonzalez, an assistant professor of astronomy at Iowa State. Ward and Brownlee were unaware of his role as a strong advocate of ID at the time of those conversations, as I recall. Nonetheless, their discussions incuded a large range of legitimate and well known scientists from many fields related to astrobiology.

    I agree that it is pessimistic but there is nothing unreasonable, at least in my opinion, in the things that they point to that are probably important for complex organisms to develop ... and if you agree that all these factors are important then it is quite possible that the product of their associated probabilities could be much much smaller than the number of solar systems in our galactic habitable zone.
     
  23. Jun 14, 2005 #22
    Last edited: Jun 14, 2005
  24. Jun 16, 2005 #23
    I think I read a critique of rare earth in an article by Darling but don't recall the specifics, I will have to pick up his book and take a look. His main critique seems to be based on guilt by association. I don't recall them crediting Gonzalez (the blatant ID'er) with the seemingly overwhelming influence on their treatise that is claimed by Darling though it is something that can probably be checked relatively easily. Granted that the conclusions give support to Gonzalez's theistic viewpoint but I think despite that (actually it should be irrelevant if examined objectively, right?) the arguments made by W and B are not unreasonable.

    Also, I'm not sure that I agree that they are using circular reasoning ... they are picking factors that appear to be important in the development of complex life for reasons based on the historical record of life on this planet and current biochemistry and physics. Of course it is wrong to argue from ignorance -that since we cannot think of another way complex organisms can develop there probably isn't another way- but I think that W and B try to make the case that it is likely that there are certain hurdles in the evolution of animals that, no matter how they are overcome, would be common to all histories based on what we think must be available to such organisms.

    Finally, I think that it really is a testable hypothesis in principle, maybe to some extent even within our lifetimes if we can find enough potentially habitable earthlike planets and can take enough spectra of their atmospheres. Of course SETI can falsify the RE position quite quickly if they are out there and we are lucky enough to detect them.

    Anyway, I am glad you mentioned Darling's book and I look forward to checking it out. As I have said before, I would love for the RE hypothesis to be wrong and I run SETI@home on a couple of machines due to a glimmer of hope that Darling's position is closer to reality.
     
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