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Space Science

A New Take On the Fermi Paradox 388

Posted by Soulskill
from the drake's-game-of-life dept.
TravisTR points out some new research that aims to update and supplement the Fermi paradox — the idea that if intelligent life was as common as we expect, we should have detected it by now. The academic paper (PDF) from scientists at the National Technical University of Ukraine is based on the idea that civilizations can't expand forever on their own. The authors make the assumption that an isolated civilization will eventually die out or go dark through some other means, which leads to some interesting models of intergalactic colonization. "In certain circumstances, however, when civilizations are close enough together in time and space, they can come into contact and when this happens the cross-fertilization of ideas and cultures allows them both to flourish in a way that increases their combined lifespan. ... Bezsudnov and Snarskii say that for certain values of these parameters, the universe undergoes a phase change from one in which civilizations tend not to meet and spread into one in which the entire universe tends to become civilized as different groups meet and spread. Bezsudnov and Snarskii even derive an inequality that a universe must satisfy to become civilized. This, they say, is analogous to the famous Drake equation which attempts to quantify the number of other contactable civilizations in the universe right now."
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A New Take On the Fermi Paradox

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  • by Black Parrot (19622) on Monday July 26, 2010 @06:27PM (#33037598)

    and no civilization has yet wanted to spend 500 years getting here.

    One of the arguments offered regarding the Fermi Paradox is that "if each colony established two more colonies, the exponential growth would fill up the galaxy relatively quickly". However, that presumes that the members of the colonizing species would be willing to live their whole lives just to accomplish someone's Grand Plan. Intelligent colonists would (I presume) be more interested in making their own colony sustainable and life there comfortable.

  • by blair1q (305137) on Monday July 26, 2010 @06:37PM (#33037642) Journal

    If they are as intelligent as we think they are, won't they take one look at us and pretend they're not home?

  • Basic assumptions (Score:5, Insightful)

    by icebike (68054) on Monday July 26, 2010 @06:44PM (#33037668)

    The bit quoted as "Eventually die out and go dark" apparently comes from this quote in the second link:

    Their approach is to imagine that civilisations form at a certain rate, grow to fill a certain volume of space and then collapse and die. They even go as far as to suggest that civilisations have a characteristic life time, which limits how big they can become.

    However, this deals only with civilizations and not intelligent beings. The Civilization may collapse, after expanding to multiple worlds, but that does not mean that everyone on these planets dies. The would live on to create new civilizations.

    Using an admittedly imperfect Earth analogy, the collapse of the Roman or Mayan empires din not lead to the extinction of humans, merely a pause in the development of civilization among that species, (us).

    So EVEN if the basic assumption is correct, you would still expect to see many inhabited worlds, populated with remnant people having "arrival myths".

    They may have once held knowledge of how to build ships, but deciding instead simply to sit tight, and not draw attention to themselves for a long enough period for any ship building knowledge or desire to wane. But new civilizations and technology would sooner or later arrive on these worlds.

    When you start with a flawed and pessimistic assumption, it seems natural that you might arrive at a dismal conclusion.

  • by Anonymous Coward on Monday July 26, 2010 @06:54PM (#33037744)
    Therefore, there must be a finite number of inhabited worlds.

    The logical deduction breaks down here. If there are an infinite amount of worlds, and you take away a few that don't have life, you're still left with infinity. (Warning: The maddening concept that the infinity of all planets is larger than the infinity of planets with life may harm your brain. Viewer's Discretion is Advised).

    Even if you said "half", "a quarter", "1%", "0.0000000001% of those planets have life", the number you're left with is still infinite. The only way you could say that the limit of the number of inhabited planets in the universe as the number of planets approaches infinity is if you have a finite number of planets with life to begin with. Right now we can say that though, as we only know of one, Earth, but it still relies on the assumption that there are an infinite number of planets, which would mean the universe has infinite mass, which doesn't really make much sense.
  • by grimJester (890090) on Monday July 26, 2010 @07:09PM (#33037922)
    The time needed for our solar system to develop life was more than a third of the age of the universe so far. Extending the Drake equation to replace communication time before extinction with odds of spreading to the next star before extinction and replacing probabilities with average time taken would make far more sense than the original one.

    We're probably just the first advanced civilization in our galaxy. No Fermi paradox, no odd extinction events, no improbably rare Earth. Why would it be impossible for civilizations to travel to another star and why would the typical time to interstellar travel be short enough that current formation rate of generation I stars is a more limiting factor than amount formed since the Big Bang?
  • Communicate first? (Score:4, Insightful)

    by CdBee (742846) on Monday July 26, 2010 @07:14PM (#33037988)
    I'd have thought, however risky we are to meet, any civilisation that's aware of us and monitoring would probably start with a generic 'hey guys, want to chat? Check where this signal is coming from if you want to know who we are'

    it might not only be human society that thinks turning up unannounced is poor form.
  • by Chris Burke (6130) on Monday July 26, 2010 @07:28PM (#33038150) Homepage

    No it doesn't. It merely assumes that a majority of them would eventually become wealthy enough to afford to create a colony or two and would do so just as their parent did. You can give each colony a thousand years to mature and still fill the galaxy pretty damn quickly.

    Right but the very fact that they are wealthy and advanced enough to create multi-generational colony ships makes me wonder why they would want to. The only obvious one is population growth exceeding the capacity of their world, but look at our world (as we naturally must for all such predictions): The richest portions of the world are the ones with the lowest population growth, including negative. People traditionally had many children because of 1) lack of birth control 2) needing extra labor for their farms 3) high mortality rate among children from illness etc. That only leaves culture as a reason to reproduce beyond replacement rate, so sure maybe the Space Catholics will have population issues but otherwise it seems plausible that wealthy and advanced civilizations will stabilize not grow unbounded.

    Then what? Resources? To even make the colony ship work I'm going to assume they have a Mr. Fusion, and once you have that you can do a hell of a lot with the resources of just one system (especially given a bounded population) and every energy-intensive recycling technique is suddenly much more feasible. Sending a small fraction of the population off in expensive colony ships is only going to exacerbate a resource problem anyway. Exploration, sense of adventure? Explorers are people who want to explore, not people who want to maybe enable their great-great-grandchild to explore.

    I'm not saying it isn't possible. I'm saying that the answer to the Fermi "Paradox" could be as simple as: Maybe the assumption that civilizations will engage in exponential galactic colonization endeavors is wrong.

  • by HiThere (15173) <charleshixsn@earthlin k . n et> on Monday July 26, 2010 @07:31PM (#33038182)

    But by the time the civilization collapses it's used up all of the readily available hydrocarbon deposits and metal deposits. (Civilization may require readily available copper deposits to be jump-started.)

    So unless you can read the old CDs...or whatever storage medium replaces them...you can't learn enough to make a technological civilization out of what's left. You can probably go quite far with ceramics, glasses, etc., but none of those lead to electronics. And if you can't get to electronics you can't extract specialized materials out of low-value ores. (Well, possibly you could fractionally distill them...but just try doing that to extract iron. Zinc [zinc oxide?] you could get that way, though. Even if you get them that way, you get compounds, not metals. You need electricity to extract most metals from their compounds.)

    I'm not sure you get a second chance at a technical civilization.

  • by Todd Knarr (15451) on Monday July 26, 2010 @07:35PM (#33038232) Homepage

    We generated our first real radio signals sometime around 1894, give or take. That means that we are completely and utterly invisible in the radio spectrum to any civilizations more than about 116 light-years away from Sol. Our radio signals simply haven't had time to reach them yet. And the same thing applies in reverse: if an alien civilization began transmitting radio signals 200 years ago but they're more than 200 light-years away from us, we won't be able to see them because their signals haven't had time to reach us yet.

    That defines the outer edge of the visibility shell. There's also an inner edge. As a civilization develops, it eventually stops transmitting radio signals as it first gets more efficient at transmitting radio (moving from pure broadcast to directed transmissions and then refining their ability to direct the transmission into tighter and tighter beams) and then starts using things other than radio. If you start listening after the last of their detectable broadcasts has passed you, again you can't see them.

    So when you're asking "If there are as many civilizations out there as the equations predict, why can't we detect them?" you also have to take into account the fact you're likely only physically able to detect a fraction of the civilizations that may exist. The rest are either too far away for their signals to have reached you, or they've been around long enough that you weren't listening when the last of their detectable transmissions passed your planet.

  • by icebike (68054) on Monday July 26, 2010 @07:57PM (#33038452)

    But again, you assume collapse due to material exhaustion, which, even for a very OLD civilization would not universally be the case, especially one that migrated to other planets.

    Why would a planet be colonized in the first place if there were insufficient materials for self support?

    By the way: There is no exhaustion of copper or metals, as any gaze into a junk yard will reveal. In fact we make mining significantly easier for future generations by concentrating all of our waste materials. And any civilization capable of interplanetary migration would be been off hydro-carbons as a primary energy source for eons.

  • by Ungrounded Lightning (62228) on Monday July 26, 2010 @08:06PM (#33038562) Journal

    My own take on the Fermi paradox comes from the observation that modern radio communication systems - spread spectrum and ODFM - approach the Shannon limit of the bandwidth's information carrying capacity. As they do that, they approach the appearance of pure noise.

    Earlier transmission systems, such as AM, FM, and analog broadcast's AM/FM hybrid, involve massive inherent reundancy and low bandwidth utilization. This makes their existence detectable (even if not fully decodable) at interstellar distances and at the resulting far worse signal-to-noise ratio than their intended receivers experience. Spread-spectrum and OFDM systems (and no doubt others yet to be invented) fill their assigned bandwidth with a close approximation to white noise, with only a small amount of redundancy to allow the receiver to detect the existence of the signal and synchronize with it. (Even the redundancy from the forward error correction is sufficiently complex that at appears as noise if the particular scheme is not being looked for.) This is why, when the signal-to-noise ratio of a digital signal becomes excessive, the reception drops out completely rather than becoming noisy.

    Bandwidth is limited by physice, but the potential valuable uses of it are limited only by imagination and cost. So other radio-using civilizations seem likely to follow a similar path of squeezing as much information as technology allows into their signals.

    If this is the case, the L term in the Drake equation ("the length of time such civilizations release detectable signals into space") becomes a measure, not of the lifetime of the civilization after it begins to use broadcast radio, but of the time from such use to the time it is supplanted by highly-efficient but not-readily-detectable shannon-limit-approaching signals.

    When estimating the number of intelligences in this galaxy using the Drake equation, L was ballparked at 10,000 years. But consider broadcast TV here on Earth (the main telltale, emitting far more power per station than audio radio): Excluding early experiments the first regularly scheduled TV broadcasts started in 1930 - and the Analog Cutoff (where most high-power analog TV stations were shut down to free the bandwidth for other purposes) is in progress now, with the US terminating all full-power analog TV broadcast in 2009, just 80 years after the first signals from that first broadcast-service station.

    So I have no feeling of loneliness just because we haven't happened to hear any civilizations in the narrow time slot when they might send DETECTABLE broadcasts.

  • by Curunir_wolf (588405) on Monday July 26, 2010 @08:38PM (#33038840) Homepage Journal

    I have a different theory.

    I think that in many cases, civilizations reach a point where a small group can convince the mass of population that they have to alter their lifestyles to prevent their own advancement from destroying their environment. Thus cowed, the rulers, without any motivation for advancing the species, and living in luxury by the labor of a vast cadre of dependent and ignorant masses, push the rest of the civilization into more primitive lifestyles.

    Preserving this stable lifestyle becomes and end itself, all ambitions of extra-planetary exploration forgotten. Eventually, the civilization runs out of local resources, too late to escape their own gravity well, and die off never having attained their potential.

    What do you think? I call it the Enviro-Gorbama effect.

  • Re:My take (Score:3, Insightful)

    by Omestes (471991) <omestes@NOSpAM.gmail.com> on Monday July 26, 2010 @10:21PM (#33039682) Homepage Journal

    Unless you think those random bits of organic gunk might grow up to be a threat to you someday. Best to destroy or co-opt them while it's still trivial to do, rather than wait for a potential rival to grow strong feisty.

    Or save their souls. We also ignore the fact that any space-faring aliens might have the same stupid hang ups as us, and be doomed to repeat our history.

    If, by some stretch, we managed to get into space, and found an intelligent species you can be sure that various sects of religious wackos will quickly try to convert them to Earthly religion. And probably, judging how these things historically worked, slaughter most of the in the process (in the name of progress and for their own good).

  • by JSBiff (87824) on Monday July 26, 2010 @10:34PM (#33039752) Journal

    What, wait, you're assuming every star system is only about 4 light years from it's neighbor *and* that every star system has a useful/suitable planetary type for the type of life that civilization is composed of? Sure, you might be able to cross the 4 light years to Alpha Centauri (or wherever), but is there gonna be a planet you can live on at the end of the trip?

    I think your 'filter' is simply that in reality, the distance to the nearest suitable planet will usually be much greater than 4 light years. Granted, our technology is still developing, but it seems to me that it's a very hard engineering task to create a vessel which is suitable to contain life, and that will not degrade so much in 1000 or 2000 years (or whatever the travel time is) that everyone on board dies. Everything wears out, eventually. Although, I suppose in space, things might wear out a lot slower with no friction (well, there is the small matter of the Interstellar Medium abrading away at your hull like a sandblaster).

    I'm not saying these aren't problems that can't be overcome, but 4 light years seems daunting enough - what if the nearest earth-like star is 100 light years away? 200?

  • by Chris Burke (6130) on Monday July 26, 2010 @10:47PM (#33039874) Homepage

    What about Von Neumann Probes? Why haven't we even seen any of them? They would hypothetically proliferate much faster than giant colony ships and should also be here by now.

    Heh. Aside from all the reasons that apply to alien radio signals or colony ships... And the same question of "would they necessarily want to?" I personally think it would be the height of irresponsibility to send out fully autonomous self-replicating probes. There's a thin line between a Von Neumann Probe and a Slylandro Probe. I would like an operator in the loop that verifies that the life-detection instruments are fully working before giving the go-ahead to eat and reproduce in a new system. But aside from that?

    How do you know there isn't a probe coasting past our solar system, checking us out, right now as we speak? It's not obvious that we could even see a probe at that distance even if we knew exactly where to look.

    That's why I ultimately find the Fermi Paradox silly to think of as a real mind-boggling paradox or proof of alien non-existence. "Why haven't we already seen solid evidence of aliens?" is so ridiculously far from being the same question as "Why isn't there evidence of aliens that could hypothetically be seen by us?" that taking the former to imply the latter is lunacy.

    The idea that we've done an exhaustive search of our little neighborhood of the galaxy and concluded that nope, there's no life here, is just completely divorced from reality.

  • Re:My take (Score:3, Insightful)

    by thesandtiger (819476) on Tuesday July 27, 2010 @12:44AM (#33040668)

    Or (insert idea here) - the number one rule of alien life is that it will be alien. We human beings on Earth have a hard enough time understanding people who merely have different cultural underpinnings in their world view; imagine what a fundamentally different biology would yield for misunderstandings.

    The only thing I see being similar regardless of the origin of species would be that the other intelligences we meet will be the survivors of an extremely long competition with other species on their world, whatever that means.

  • Re:My take (Score:3, Insightful)

    by thesandtiger (819476) on Tuesday July 27, 2010 @12:51AM (#33040716)

    What's amusing is that you seem to have an unprovable belief that religion is a disease to be cured is somehow obvious.

    The fact that a majority of the people on Earth disagree with you demonstrates not only that it isn't obvious, but that you are probably just as irrational in your beliefs as those people are in theirs. But at least they have the intellectual honesty to admit it's faith.

    I'm not remotely religious, but I'm also not so disingenuous that I'd dismiss a majority of humanity as somehow suffering from a disease that needs to be cured. For many people faith fills a void; I think rather than the idea that faithless people are somehow evil, faith helps people who might otherwise be evil because they need some system larger than themselves to believe in do good things. Why would something that prevents a lot of people who would otherwise do things harmful to the species need to be cured?

  • by Anonymous Coward on Tuesday July 27, 2010 @01:30AM (#33040954)

    Most of the Fermi colonization models *require* magic-like nanotech and AI abilities that we're not really sure are even possible. Basically, the probes have to be cheap and small and intelligent. In the faster models they have to be able to mine asteroids to replicate more probes to send out. Either way, they have to be good enough to build space habitats from available material in the destination system, or outright terraform planets; then they need to rebirth the species by artificial womb and educate them and have a civilization take root. Without AI around human-strength, the species-raising part is very hard. Without godlike nanotech, everything else is VERY hard.

    If we don't have those things, then we have to invent some extreme life extension techniques, or really great hibernation tech, or figure out a way for a multi-generational colony ship's mini-civilization to be stable for a hundreds-of-years trip and a hundreds-of-years terraforming project at the end of it. We on Earth have to stay stable that long too, according to this new research's ideas, because we and the colony will have to at least be able to talk to each other, otherwise the odds of failure on both ends goes up. (If we have to actually send ships back and forth, the expense goes oh so much higher). And after multiple hundreds of years of not breeding past replacement speed, the colony is not likely to fill its planet(s) quickly; if it only climbs to a few hundred million people and then levels off because they've got a nice utopia and the survival of the species is already assured, then they'll never have the economic ability to send their own colony arks. The Fermi models generally sidestep any kind of genetic or cultural change - they rely on automated probes, or, failing that, assume that all the child civilizations will be as gung ho about expansion as the one that send them.

    This, and the range constraints that would result from needing to use large colony ships and stay in useful communication range, could very well put a lot of pressure on a colonization bubble, keeping explored space kinda small. If you need other colonies alive, then that means ANY system going silent becomes your meta-civilization's first priority to re-colonize. At some point you may be sending more ships back inward than you are sending outward, until you hit an equilibrium.

    Further, if colonization is expensive enough, maybe none of the inhabited systems bother to found new colonies after the total is considered high enough. After all, there's not much that could take out ten colonies at once that wouldn't also fry the next hundred systems over too. Maybe after your species has ten stars, you start to turn inward. I'd expect us to see Dyson spheres (or partial ones) out there if intelligent life is relatively common but colonization is relatively difficult. After all, once you get advanced enough to start controlling your star's life cycle, you've gained additional billions of years of useful work out of that star. And it could be that life at a potentially spacefaring level hasn't arisen in our galaxy until fairly recently - even if the first one was a billion years old today, there's no pressing need for them to have expanded very far from their origins. Ten Earths like ours could potentially mean 80 billion people to talk to. Ten star systems like ours could support more if they have multiple useful planets each. Ten star systems like ours, utilized to the absolute fullest, might pass a trillion citizens.

  • by warrax_666 (144623) on Tuesday July 27, 2010 @03:19AM (#33041282)

    So what you're saying is that those people who have faith would go around murdering their neighbors, raping and pillaging, etc. if they didn't have "faith"?

    That's complete bollocks and you know it.

    Good people are good and bad people are bad. Religion is a system of control which can be (and has been) leveraged for both good and bad.

  • by TheTurtlesMoves (1442727) on Tuesday July 27, 2010 @06:07AM (#33042004)
    That the *hard step* is the evolution of complex life, is one of the proposed solutions to the Fermi paradox. We have some evidence to support this. Basically everything was single celled, then one single cell life form swallowed another and made it a DNA management machine (nucleus). After than the explosion of complex multicellular life happened. This appears to have taken billions of years. Its quite possible that such an event is "rare" in the sense that it always takes a really long time even in favorable conditions.
  • Re:My take (Score:3, Insightful)

    by tehcyder (746570) on Tuesday July 27, 2010 @08:02AM (#33042646) Journal

    Hawking's a moron.

    Seldom can that unpleasant word have been more inaccurately used. He may be totally wrong about many things, but one thing is for certain, and that is that Stephen Hawking does not have a below average IQ.

  • Re:My take (Score:1, Insightful)

    by Anonymous Coward on Tuesday July 27, 2010 @08:17AM (#33042760)
    Psssst... didn't you get the word? Bashing religion is considered cool, edgy, hip, fashionable and is prima-facie evidence of social and mental superiority over the homo-phobic, animal-abusing; in-bred simpletons who are so stupid that they don't even realize the enlightenment their social-progressive "betters" are trying to bestow upon them. (no sarc tags required)

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