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20,000,000,000 habitable planets in the galaxy - So where is everyone?

Discussion in 'Speaker's Corner' started by NeilFawcett, Nov 6, 2013.

  1. Zethor

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    I would say that civilizations of any kind are implausible, considering the fact that only one species on this planet created one, despite billions of species existing over bilions of years.

    Humanity's knowledge is certainly not obsolete, this isn't 500BC when we believed rocks turned into frogs and lightning is thrown by cloud residents, we have a solid (yet incomplete) understanding of the Universe and any future discoveries will not throw the current ones in the bin. The idea that we are to advanced aliens like ants are to us, is absurd. We're capable of abstract ideas, our imagination is limitless, there's nothing out there that we can't understand so why would it ruin us?
     
  2. Deadly Ferret

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    I don't like to brag, but I went to Space School as a teenager. I once had a chat with a geezer named Heinz Wolff, who explained to me the answer to this question in the form of an equation. I can't remember the equation, but it was simple in design.

    Remember from statistics lessons that little probability gem, "for 'and' you multiply, for 'or' you add"?

    The equation was essentially a horizontal probability list of all the conceived of variables that are considered pre-requisite to intelligent life forming on a given planet (based on known statistics derived from averages, i.e. x percentage of planets have gravitational field strengths between a and b) with a shedload of x's in between, the whole thing bracketed, and divided into one. Wittles it down to a very, very small probability of intelligent life forming on a particular planet.

    If you place stock in the theory, then it makes us incredibly special. :D
     
  3. hola_adios

    Wise Guy

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    Kind of relevant:

     
  4. Angilion

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    Evolution from the first life, something less sophisticated than a bacterium, to intelligent life capable of developing technology is likely to take a while. It's hardly relevant to consider archaea, bacteria, amoebae, etc, etc, in the context of species that could create a civilisation at least roughly on a par with our own.

    There's somewhere in the region of 10^21 stars in the observable universe. The formation of planets is, as far as we know, commonplace in stellar systems. Many of those planets will have existed for billions of years and it's possible that many of them would have done so in conditions that would be capable of supporting life. I think we don't have anywhere near enough knowledge to assess the likelihood of other civilisations existing now or in the past with any degree of accuracy, though it would be startling if amongst that vast multitude of star systems ours is the only one with civilisation. There are many things that are (as far as we know) necessary for life to occur and evolve to our level, but 1 in 1,000,000,000,000,000,000,000 is a truly startling level of rarity. I think it's not implausible that there might be at least 2 in 1,000,000,000,000,000,000,000.

    That would be true if humans were as intelligent as these hypothetical aliens. If we were behind but could catch up, that would be a difficult time but also an opportunity. But I was specifically talking about a scenario in which these hypothetical aliens were significantly more intelligent than humans. So humans could never catch up, never contribute. There would be no point in any human trying to become a scientist or a mathematician or an engineer or a medical researcher or a doctor or anything other than a consumer.

    Your answer contains the assumption that humans are the highest possible intelligence in the universe ("there's nothing out there that we can't understand"), an assumption that I think isn't necessarily true. Would you explain why you think it's impossible for any other species anywhere in the universe to be more intelligent than humans (and therefore able to understand things that humans couldn't understand)?
     
  5. Angilion

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    You're probably thinking of the Drake equation. It's useless as an equation (you can't solve the equation without knowing the values of the terms and if you know those you already have the answer), but he never intended it as one. He intended it as a means of promoting discussion of the idea of intelligent life elsewhere.
     
  6. Rroff

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    That is some scary scale.
     
  7. Zethor

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    It took 3.5b-4b years for life to create the first civilisation, roughly 1/4 of the age of the Universe. In other words, while the Universe is vast enough to allow many planets with the right conditions to exist, it isn't old enough to allow many civilisations to develop.

    Despite the fact that Earth obviously is a planet suitable for life, only one form of life appeared on it and everything else evolved from it. Forget everyone out there, a better question is, "Where is everyone down here?". Furthermore, if one of the many meteors that were hitting the primordial Earth had landed in the primordial pool where it all began, destroying the common ancestor, life would have dissapeared forever. Everything we now see has started from just one thing, a startling fact but a fact nonetheless. I therefore don't think it would be startling if we're the only civilisation, considering how things have played out on our planet.


    You put too much emphasis on intelligence which is a vague concept that could mean lots of things. It doesn't matter how smart aliens could be, Pi would still be Pi, gravity would still be gravity, the sun would still use hydrogen and helium as fuel. Our brains evolved to kill things, keep us safe and procreate and it's been virtually unchanged for 15.000-50.000 years, the same brain that was then throwing sticks and stones has recently put a man on the Moon.

    You're making the assumption that higher types of intelligence could exist (why?) where as I have simply noticed that abstract thinking and the scientific method has allowed us to understand (to some degree) everything we've ever encountered, from the atom to the massive black hole in the center of our galaxy. I see no reason why anything in the Universe would be impervious to our methods, they've been tested countless times and have yet to produce a single failure.

    Could there be another civilisation in the Universe? Yes, although I've explained why I find it unlikely. Could they be much more intelligent than us? Again, it's possible but irrelevant because any knowledge they would have would be understandable through the scientific method, given enough time.
     
  8. Skunkworks

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    Mind boggling isn't it?
     
  9. kedge

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    From a secular worldview human beings are the highest known intelligence in our known universe, this is not based on assumptions this is based on proven observations, it is clearly demonstrated or manifest by intelligent design such as complex machines, no other life form on planet earth can create complex machines like human beings can. Until secular science can actually prove otherwise then significant life forms with intelligence that matches or exceeds our own that resides in outer space or on some other planet is just an assumption.I guess secular scientists will continue the search, but what if time is running out? is the search in vain?.
     
  10. Angilion

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    True, but irrelevant as a reply to the text you wrote it in reply to.

    I referred to the assumption that humans are the highest possible intelligence in the universe, not that humans are the highest intelligence known to humans.
     
  11. Angilion

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    That doesn't follow - if you allow 3.5 to 4 billion years for development from first life to civilisation that still leaves a great deal of spare time. As you say, it's roughly 1/4 of the age of the universe. The universe is old enough to allow the existence of many planets that have existed with the right conditions for roughly 1/4 of the age of the universe.

    Evolution. That's not the difficult part to explain - if variation is possible and there is enough time, life will evolve into various forms. Biogenesis is the difficult part to explain, which is why we can't be sure how likely or unlikely it is.

    We also can't be sure that only one form of life appeared on Earth. We can be almost sure that only one form of life is the common ancestor of all life billions of years later, but that's not the same thing.

    Maybe that happened. Maybe life on Earth started in a hundred pools over some amount of time and died out in 99 of them for various reasons.

    I think that it's plausible that there is at least 1 other. I'm not saying that it's certain. I'm not saying that there are probably hundreds or thousands or millions. I'm not saying that it's commonplace for planets to exist with the right conditions and to remain stable in those conditions for long enough for life to somehow occur and to evolve to people at least as intelligent as humans and with at least as great an ability for tool use and for them to develop civilisation and technology to at least the same level as humans. I'm not saying it's commonplace at all. Given the number of things required for it to happen, I'd say that it's probably very uncommon indeed. But not that it's implausible for it to have happened more than once, not given the known size of the universe. That's the position I was arguing against.

    True, but that doesn't make it absolutely certain that humans could compete on an equal footing with any other people who might exist.

    That's how this subsection started - I suggested one possible reason why a hypothetical civilisation of people from elsewhere might know that humans were here but not contact them.

    Because I have not made the assumption that they can't.

    Good argument, but I think it doesn't prove that it's implausible for any other civilisation to exist anywhere in the universe and it doesn't prove that it's impossible for any people to exist that humans can't compete with on an equal footing or that human civilisation would be fine if humans were unable to compete on an equal footing.
     
  12. Zethor

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    It all comes down to what the conditions for life to start are. I believe it would be odd if many forms of life started out in the primordial soup on Earth, with only one surviving later on. A more likely scenario is a form of life landing on our planet and colonizing it, which would make Earth a suitable planet for life to flourish but not for it to start. The varied Darwin's finches in the Galápagos Islands have one ancestor who happened to fly there at some point, million years ago. They have vastly different sizes, different tools, yet they are all related, just like life as a whole.

    Considering that most of the solar system's planetary mass belongs to gas giants, I would say that's the most likely place of origin. Given the nature of gas giants, particularly their inherent instability, my final assumption is that evolving into complex organisms is probably impossible on those planets.

    I therefore conclude that our civilization is a chain of extremely unlikely events, starting with life occuring, surviving through space for long periods of time, landing on a suitable planet and reaching a level of complexity sufficient to allow a brain capable of creating culture and controlling fire. Each event in my hypothetical scenario has extremely low chances of happening and the chance of the chain of events to happen is much lower.

    Nothing would be more interesting than actually finding intelligence out there, I just don't see it happening, even if my assumptions are wrong, the distances between stars are just too big. The best we can hope for are our microbial cousins, on one of the solar system's moons.
     
  13. silversurfer

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    The odds of earth being wiped out by a meteor despite the protection of Jupiter are likely far better then humans ever discovering a similar planet and ecosystem elsewhere
     
  14. Angilion

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    We're pretty much in agreement there.

    Which means we should be in agreement that anything else is highly speculative because we don't know what the conditions for life to start are or even how many different conditions there are. Maybe the conditions are spectacularly rare. Maybe they're relatively common. We really don't know.

    Then there's the chain of unlikely circumstances that leads from life to intelligent life which develops technology. How unlikely is each step? We don't really know, although we can make better guesses for some of them than we can for biogenesis. Does it have to be the same steps for all life? We don't really know that, either.
     
  15. SPG

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  16. Columbo

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  17. Robosapien

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  18. Skunkworks

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    With the right conditions the step from non-life to life might not be a big deal:

     
  19. Robosapien

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    I haven't watched the video yet, but I already know it's not a big deal. We're only animate matter, no different to the rest of the junk that surrounds us, an ongoing chemical chain reaction that hasn't quite reached the end yet.

    I digress, the video is probably far more intelligent and I will watch before continuing with my diatribe.
     
  20. olivier renault

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    Not quite. The universe went through phases, some quite long, unsuitable for life. Organic chemistry could not have happened without carbon, nitrogen, ect... These requires several star generations to produce and recycle the variety of compounds.

    It is argued that we are in some kind of 'golden age', where the universe is old enough to generate complex chemistry, and young enough to sustain that chemistry (the Universe isn't just full of brown dwarves, neutron stars and black holes).

    In a sense, you could say that life happened as soon as it was possible. From our perspective, it seems that it just took a long time to arrive at us (for about 3 billion years, Archean and Proterozoic periods, just unicellular life and proto-life). There is no reason why it couldn't have happened sooner and faster, given different environmental conditions, fortunate and unfortunate events included.

    But yeah, plenty of time. What's a couple of billion years here and there. How could we begin to imagine a civilisation enduring for even for just a few million years, which is nothing in cosmic terms.
     
    Last edited: Apr 13, 2015