We Are Not Alone

Discussion in 'Astronomy, Exobiology, & Cosmology' started by TruthSeeker, Feb 16, 2009.

  1. krokah Registered Senior Member

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    What makes people think that the search for ET rests for looking at radio waves transmitted at the speed of light. This is to slow for galactic communication. I think with a few jumps in knowledge that we will find other methods of ftl communication. Until then, we are stuck looking for transmission waves that may never bear fruit.
     
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  3. BenTheMan Dr. of Physics, Prof. of Love Valued Senior Member

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    There are pretty plausible arguments about why a civilization would use light as a means to communicate. For example, life has to form where there are sufficient concentrations of elements other than hydrogen, helium and lithium present, which means a generation 3 star. (Intelligent) Life probably forms after several billion years, which means that the star has to look a lot like our sun. This means that any eye sight that intelligent life will have will probably be very similar to ours. Any intelligent life will probably discover Maxwell's laws, and Special Relativity, and find out that the speed of light cannot be exceeded. They will probably also discover how easy it is to use electromagnetic radiation to send information.

    SETI isn't looking for civilizations that are much advanced from our own, they are looking for civilizations which are at a similar place in their history as we are.
     
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  5. cosmictraveler Be kind to yourself always. Valued Senior Member

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    The first transmissions SETI sent aren't even half way to a nearby star as yet! Think how long it will take any other alien worlds to connect with us , if they are even trying.:shrug:
     
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  7. BenTheMan Dr. of Physics, Prof. of Love Valued Senior Member

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    Well, you can estimate the time it takes a species to colonate the galaxy, and it takes on the order of a million years. Probably you have to assume that the resources on every planet are more or less the same, and that there exists suitable planets for colonization, etc. etc.

    But on galactic timescales, a million years is nothing! This is, more or less, the Fermi paradox. If there are many intelligent life forms in the galaxy, it is unlikely that we're the most advanced. If that is true, then there are civilizations much more advanced than we are. If this is true, then those civilizations should be colonizing other stars by now. I don't know how to estimate the probability that that other civilization just hasn't found us yet.
     
  8. PsychoticEpisode It is very dry in here today Valued Senior Member

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    A galaxy with 100 billion stars @ say minimum 5 planetoids including moons in the system. Granted some stars don't last but new ones are always popping up. So that is 500 billion planetoids. In 1 million years, that's 5000 per year(13-14 per day). That's a lot of travelling in a short time. When you find one with advanced life or with life in general do you just move on? What would we do if ever in that situation?
     
  9. Nasor Valued Senior Member

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    Two points I'd like to make:

    1. Several people have mentioned that life appeared pretty quickly on Earth, but it took it a long time to achieve complexity and intelligence. As I just spent a long time arguing in another thread, you can't really extract any meaningful information from this, because our sample size here is one. It might have been an incredible stroke of luck that it "only" took a few billion years for intelligent life to appear, or it might have been incredible bad luck that it took so long. We have no way to know at the moment.

    2. As for the Fermi paradox, remember that we really have no way of knowing whether or not aliens might have visited us in the past, or what their motivations in settling various planets might be. Maybe some alien civilization has colonized every planet in the galaxy that they found hospitable, but they didn't like any of the planets in our system. Perhaps they visited Earth a million years ago (or a thousand years ago), and were disappointed to see that we have an oxidizing atmosphere rather than a reducing atmosphere, so they just moved on. Although I'm not one of the nuts who suspect that aliens are constantly visiting us and abducting people etc, I think it's interesting that if aliens had visited our solar system even a few hundred years ago, we probably wouldn't have known about it. Heck, some alien probe the size of a bus could be coasting through the solar system and beaming data back home with a directional antenna/laser/whatever right now and we probably wouldn't see it.
     
  10. BenTheMan Dr. of Physics, Prof. of Love Valued Senior Member

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    Well, the point is, once a civilization has become large enough, they probably don't start just one new colony. They probably start several. Then, in a matter of hundreds or thousands of years, the new colonies start new colonies---so it grows like an exponential. If there are two advanced civilizations, the effect is enhanced, not by a factor of two, but by a POWER of two.

    If there are thousands of intelligent civilizations, then it seems very implausible that we haven't been contacted by at least one civilization, EVEN if there are 500 billion planetoids (which is unlikely).

    The exception is if we're atypical---perhaps there was a series of events that we went through that accelerated our development. Perhaps we got a Newton and an Einstein much quicker than other civilizations. Perhaps we were one of the first intelligent species to evolve, and it's up to us to contact others. Perhaps we're one of the LAST intelligent species to evolve, and we're like some isolated Natives that some galactic society is protecting. Either way, all of these things would imply that we were ATYPICAL, which is hardly a productive assumption.
     
  11. Quantum Quack Life's a tease... Valued Senior Member

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    but what do you mean when you say "advanced" intelligences?

    If some race was capable of surviing enough to populate a galaxy why on Earth would it want to contact us? Wisdom alone would imply the "prime directive" as demonstrated in the film series "Star trek"

    Advanced intelligences does not just relate to scientific knowledge but also to interpersonal development [ etc ] as well...
     
  12. BenTheMan Dr. of Physics, Prof. of Love Valued Senior Member

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    Possibly. But this is another assumption.

    The likeliness of your proposition depends on e^(- # of assumptions ).
     
  13. Quantum Quack Life's a tease... Valued Senior Member

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    but of course.....but if we are going to speculate at least we could try to do it in a way that is more thorough. Is my defence...

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  14. BenTheMan Dr. of Physics, Prof. of Love Valued Senior Member

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    Sure, but we can't speculate about galactic law. The point is that the numbers quoted in the OP are pretty ridiculous, and probably only mentioned to get science journalists to write about them.
     
  15. draqon Banned Banned

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    well he had to get those numbers from somewhere, he couldnt just make them up, or could he?

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  16. Exeter Registered Senior Member

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    This really gets me thinking. I have to conclude that if there are others out there, either they are way less advanced than us, or way beyond our ability to detect them. Of course we are really thinking inside a little box. I do not think that we are as advanced as we see ourselves to be. And I think if there are others aware of us, and they are beyond our scope of detection, they have probably been here for a very long time already.
     
  17. Quantum Quack Life's a tease... Valued Senior Member

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    Quite a reasonable position to take I think.
    I tend to think we sometimes underestimate though, just how unique this planets circumstances are regarding orbital dynamics, solar environment, galactic environment and most importantly the ratio of liquid water, frozen water and water vapour are.

    I would think that even when applying pseudo infinity to the proposition of other intelligent life out there universally we would find that intelligent life sustainability is a lot less than is often speculated as being the case.

    Say for example 3 or 4 races per typical galaxy might be more in the order than thousands....

    But even so this presents and interesting possibility given the deviations from the mean spread over and entire universe....hmmmm

    It also means that some races would be millions of years ahead of us and millions of years behind us in the evolution of their intelligences.
     
  18. Quantum Quack Life's a tease... Valued Senior Member

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    It is IMO the fixation on the speed of light that is our greatest scientific hurdle.
    When we can resolve the issue of the how and why of universal constants then and only then can we make such statements about the veracity of what we THINK is universal laws regarding energy thus light.
    To travel the stars, galaxy would require dumping this so called FTL law.
     
  19. BenTheMan Dr. of Physics, Prof. of Love Valued Senior Member

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    That means that we are atypical.

    Well, you can't "dump" a physical law if you decide you don't like it. Likewise, you can't assume that, just because it is a limiting factor, there must be some new physics that circumvents it (as many here are trying to do).

    To make any kinds of assertions about the existence or non-existence of intelligent life, you cannot make wild assumptions and hope to be taken seriously. Given the drive, we could build a ship which could get us to the next star on the order of 50-100 years with current technologies. There are other serious problems with interstellar travel (i.e. cosmic rays---everyone would have cancer by the time we got where we were going).

    So, either we can frame this discussion with a reasonable set of assumptions (speed of light can't be surpassed, our civilization is typical, etc.), or we can frame it with unreasonable ones (we are atypical, speed of light can be "dumped", etc.). This is what decides whether we are making a scientific discussion, or a discussion about science fiction.
     
  20. BenTheMan Dr. of Physics, Prof. of Love Valued Senior Member

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    This is what we're discussing, whether the assumptions he had to have made are reasonable, given that we have no tangible evidence of extra-terrestrial intelligence.

    Well, yes. Who's going to check them? What experiment can you do to verify his claim?
     
  21. Cazzo Registered Senior Member

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    I agree with a lot of this.
    I read in a scientific article about a year ago pointing out what you said, where life might be easy to pop up on many planets, but it may take so long for intelligent life to evolve that a vast majority of planets with life probably just have primitive life.
    Nevertheless, it would be fasinating to see that life (through a powerful telescope(s)) without interfering it.
     
  22. Exeter Registered Senior Member

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    If there were advanced civilizations as we understand the concept, and our radio waves and such have reached into the Galactic neighborhood as I understand they have, then it does not look promising in hoping and wishing that intelligent beings resembling us even exist. If so, we would have substantial proof already of their activities as well. Another point to ponder is the chance that even if it were so, they might by very much like us in that they are not perfect. that in itself is not good news. I think of the Spanish finding the Incas, after sailing across the ocean. Disaster may await in the wake of our heart's yearnings.
     
  23. cosmictraveler Be kind to yourself always. Valued Senior Member

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    I have been for many years! :cheers:
     

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