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Fermi Paradox: If the Universe Is Teeming with Aliens, Where Is Everybody?

51 points by obblekk 13y ago

3pt14159 13y ago
https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CEEQFjAB&url=http%3A%2F%2Fwww.astro.ufl.edu%2F~lebo%2FAST2037%2FFermi's%2520Paradox%2520-%2520Stephen%2520Webb.docx&ei=kMrRUqzyDsX32QW2lIFQ&usg=AFQjCNHKQDX6K8mCoXHHuGCWhE_WHRh3yw&sig2=6okCviy35CLcGaJQAAfOQg https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd... Edit: I'll add one to the above: it might be that there are enough hostile forces, or at least the possibility of enough hostile forces, to make every technologically capable civilization conclude to travel near the speed of light to protect themselves from relativistic bombs. (Objects going very close to the speed of light. Impossible to detect in time to deflect, a form of advanced weaponry.) Each alien civilization sees that there are no observable civilizations and decides that the ones that have existed either died or fled into near-the-speed-of-light vehicles. They rationally conclude to do the same, at least while they advance their technology and search for life. The unfortunate part is that time goes by much faster for us than it does for them, (which negates the advantage that many early civilizations would have had).
exratione 13y ago
To preempt some of the usual thought on this topic: no solution to the Fermi Paradox can rely on every civilization taking a certain direction. It doesn't matter how strong the incentives are for any particular course of action, the numbers (of stars, planets, etc) even in just our galaxy are so very large that even under rare life assumptions there are still going to be an enormous number of civilizations at any given time, never mind over all history. Some of those will have (or will have had) subcultures that generate self-replicating colonies, probes, or whatever. Those visit every stellar system in the galaxy in a very short time frame. Possibly viable solutions include: - We are simulated. - Stochastic colonization leaves long-lasting uncolonized voids at all scales. - Wolves. (Ecological wolves intent on making everything look natural, but since they get to be unitary, they can be as odd as they want to be). But non-wolf Great Filter arguments have the same issues as arguing that all civilizations sublime, or leave, or whatever. There is always going to be someone who doesn't.
- MrScruff 13y ago
  the numbers (of stars, planets, etc) even in just our galaxy are so very large that even under rare life assumptions there are still going to be an enormous number of civilizations at any given time, never mind over all history. The problem is we have no way of estimating the probability of life emerging given favourable conditions. It could be 1x10^-100 for all we know.
  - jjoonathan 13y ago
    Life emerged very early in the geological history of Earth. The probability of this happening is greater under the "P(life|conditions)≈1" model than under the "P(life|conditions)≈0" model. Our historical observations give the "P(life|conditions)≈1" model greater likelihood. It's not exactly proof, but it's enough to convince me.
    - argonaut 13y ago
      Selection bias.
      - jjoonathan 13y ago
        > Selection bias. Elaborate. If you're referring to the anthropic principle, I don't see how it's relevant to my argument.
        argonaut 13y ago
        Historical observations of sample size 1?
        jjoonathan 13y ago
        Not strictly relevant. If your hypothesis is extreme, a single observation can make its posterior probability small. For instance, suppose that Alice gives you a coin and says "it lands on heads 99% of the time" (hypothesis A) but Bob calls BS and says "it looks like a regular quarter, so it should land on heads 50% of the time" (hypothesis B). You assign prior probabilities of 50% to A,B because on one hand you can't imagine how anyone could engineer a coin to land on heads 99% of the time, but on the other hand Alice is a great engineer, so you don't know what to believe. If you flip the coin a single time and get tails, your experiment strongly supports hypothesis B over A. OTOH, if it landed on heads, A would be weakly supported over B. We started with an even prior, so the posterior probability of A,B are proportional to their likelihoods: P(A|t)≈2% and P(B|t)≈98%, while P(A|h)≈66% and P(B|h)≈33%. Let's say that a typical planet remains habitable for 8b years and it takes 4b years from the emergence of life to the emergence of intelligent life, so according to the anthropic principle life had a 4b year window in which to emerge. Under the model where P(emergence)/time is tiny, the probability of life emerging in the first billion years is ~.25. Under the model where P(emergence)/time≈1, the probability of life emerging in the first billion years is 1. With even priors, the posterior of P(emergence)/time≈1 is 80% and the posterior of P(emergence)/time≈0 is 20%. It's not scientific proof of anything, but it's enough to make me consider alternative explanations for why life is rare.
krisgee 13y ago
Personally I think civilizations tend to undergo a singularity or destroy themselves eventually and the exceptions to those two cases are rare enough that communication becomes exceptionally rare.
- alan_cx 13y ago
  That is as depressing as it is plausible. Nice that its such a simple theory, but rings more true than any other.
- obblekk 13y ago
  By singularity, you mean the creation of artificial intelligence? If so, then shouldn't we be encountering these AIs?
  - sitkack 13y ago
    No, they would become addicted to pleasure stimulus, their version of digital heroin and become "unproductive"
memracom 13y ago
Why does everyone assume that if life has existed on another planet for a billion or two years, it must necessarily be similar to life on our planet and be intelligent with some sort of civilization? Why could it not be a planet filled with brainless jellyfish and green algae? People forget that our planet has been through several catastrophic events that happened at certain times in our planetary evolution, and on other planets those events did not happen, or happened at different points in their evolution, or those events had a more severe impact. Things like the snowball earth phase, and the comet that triggered the die off of most dinosaurs. Maybe most planets are inhabited by symbiotic colonies of advanced trilobites 20 meters long crawling the ocean floor eating the abundant sponges. Have a look at the wierd and wonderful pre-cambrian life forms that somehow combined to create the kind of animalia that we know today. What triggered that? And earlier, what triggered the abundant bacterial mats to start forming mobile colonies? Sure, life is everywhere in the universe but the trajectory that life took on earth will be exceedingly rare and we may never encounter another such planet even if we develop advanced star travel.
- obblekk 13y ago
  Part of the Drake equation is multiplying by the probability that intelligent life evolves. Of course we only have one data point, but it seems like intelligence is a pretty good response to many evolutionary pressures and so is likely to come about over time. Of course, this depends on how frequent you think intelligence is. I think most people assume it's very frequent.
- millstone 13y ago
  We should take your idea and push it farther: We're not looking for life. If we found an advanced civilization of intelligent robots, would we shrug and say "too bad they're not alive?" Of course not. So it's not life we hope to find.
- EliRivers 13y ago
  Why does everyone assume that... They don't. They really don't. Do you honestly think you're the first person to ever think of this?
- 13y ago
coenhyde 13y ago
I would say the highest probability is that we're in a zoo. We'd be pretty interesting to watch as a blossoming civilization.
- api 13y ago
  Given that there are many stars that are far older than the Sun with Earth-like planets, this is not that far-fetched. We have already started setting aside regions of our own planet as nature preserves, so it's not hard to imagine someone incredibly more advanced than us reaching similar philosophical conclusions and doing so on a solar system or star cluster scale. This might also involve an element of self-interest on their part. Perhaps intervention has been shown to produce dangerous results.
thret 13y ago
"Page xx is not part of this book preview" Sigh, I hate crippleware. I do love this paradox though, it makes for enjoyable conversation over a bottle of wine with just about anyone.
sigzero 13y ago
I believe we are it. That said, if there is alien life it could be at the same stage of industrial development that we are and it will be a long long long time before we meet.
soneca 13y ago
Not long ago I read a fiction piece (linked here in HN)that would imagine the world (and universe) in 10^1, 10^2, 10^3, 10^4, 10^5, 10^6... years. In this tale, Earth would have several species achieving intelligence, all of them failing on interestelar colonization, and the last one, the wisest, figured out from the basic physics knowledge they develop, that this kind of travel would be impossible. This basic assumption is very strong for me. Even if one civilization can travel at light speed, the multiple civilizations on our universe right now could be at millions of years of distance one of other.
- akkartik 13y ago
  Yeah, that's a good one: https://news.ycombinator.com/item?id=6860839 https://news.ycombinator.com/item?id=6860839
twocommas 13y ago
A good overview of the "Great Filter" in the context of the Fermi Paradox: http://en.wikipedia.org/wiki/Great_Filter http://en.wikipedia.org/wiki/Great_Filter
- kordless 13y ago
  My personal theory is that dark matter is the great filter. We can't see them because they've taken it to a whole another level.
belluchan 13y ago
Enjoying the virtual reality world they made, which is probably better than the real world. If you are smart enough to create a virtual world in which you can do almost anything you wanted, why would you give two shits about the real world. Modern day gaming is the beginning of something much more significant in my opinion.
- api 13y ago
  I consider this a dark possibility. It means that intelligence, by producing minds capable of hacking their hedonic desires, ends in nothing but a prolonged orgy of complex masturbation.
- guard-of-terra 13y ago
  Gaming is fun until it bores you. I play from time to time and I certainly would not like to replace more of my life with games. I'm in it not for pleasures but to see what's next and to affect it. Some individuals will remain active in the virtual society. Active and with lots of technical ability.
- bloodorange 13y ago
  Because the real world has surprised for us (and them) to discover. In search of the unknown, humankind has discovered a lot...
- akiselev 13y ago
  That may be true for some (many? most?) people, I could think of a couple of reasons: a) Desire to explore nature's imagination instead of that of another human or AI. Perhaps we never hit a limit of computation, but there is an entire expanding, constantly growing in complexity universe out there to understand! b) Even with artificial penalties, I doubt any virtual world could carry the same perceived risk as going out into the real world and risking getting eaten by a black hole or burned by an exploding supernova (assuming of course, you knew of/could tell the difference).
  - belluchan 13y ago
    In the future, I think that even when we end up interacting with the real world we'll have a virtual one mapped over it, ala alternate reality stuff. Check out Rainbows End for what I mean there. We can't stop interacting with the real world, but I imagine in the future most people wont. Current boredom is a reflection of our current technology and creative state in virtual worlds, not indicative of what the future will hold, it's only going to get better and while nature is amazing is so many ways human imagination trumps it. Whenever we do see something new we take it and add to it.
whatshisface 13y ago
What if it's easier to build a utopia than a starship? We already have way more money going into entertainment than into space exploration, it's not that hard to imagine that all sentient species eventually learn how to hack themselves into permanent happiness, and then conclude they have no reason to risk death on the final frontier.
- sanoli 13y ago
  A lot of human, throught humanity's history, had the material means to live a pretty pleasant, labor-free life, and yet chose a different path, away from hedonism. I suppose this will still be true many centuries from now.
  - burke 13y ago
    Pretty much any organism that manages to develop the intelligence to build a starship will have a long history of evolution. Their mindset will presumably be guided by ancient evolutionary pressures. For us humans, we're partially motivated by a desire to explore and understand our surroundings. I think it's realistic to assume that at least some subset of aliens should be motivated by the same exploration drive.
- akiselev 13y ago
  What is the probability of such a utopian society going its entire existence without at least one group of individuals with the resources to go out into the universe pulling the trigger on the decision to risk their lives? This ofcourse requires some projection of our ideas of happiness onto unknown alien beings, but then why not also project boredom? If anything, we have seen that nothing in nature really stays the same. It is ever changing and evolving.
  - belluchan 13y ago
    When I predict that VR will trump reality I never mean to imply a virtual happy Utopia or that such a thing was inevitable. Our future might be a virtual dystopia for all I know, but virtual reality is my bet where most intelligent beings end up going. I think virtual worlds > reality would explain the Fermi paradox nicely.
patrickmay 13y ago
I find the argument that we're in a simulation rather compelling: http://io9.com/5799396/youre-living-in-a-computer-simulation-and-math-proves-it http://io9.com/5799396/youre-living-in-a-computer-simulation...
- saidur 13y ago
  I think you would enjoy Thomas Campbell's work :) https://www.youtube.com/watch?v=fT8LaMrn_MM https://www.youtube.com/watch?v=fT8LaMrn_MM
  - tcgv 13y ago
    I really liked his definition of consciousness: "Consciousness is the only thing that is fundamental. Everything else is derived from consciousness, including this physical reality."
api 13y ago
I'll toss another one in: What if net-positive-EROEI controlled fusion is impossible? We have only succeeded in producing nuclear fusion in two ways: atomic bomb primers and net-negative-EROEI reactors. Atomic bombs are technically usable as space propulsion (Google Project Orion), but the max velocities reachable are only on the order of 4-8% the speed of light. At that rate, interstellar travel is severely curtailed to only the closest groups of stars. We're talking over a hundred years to Alpha Centauri if you leave time (and reserve extra mass) for acceleration and deceleration. Net-positive-EROEI controllable fusion is the only power source I know of that could allow anything near practical interstellar flight, so if it's not possible for fundamental physical reasons I'd conclude that interstellar flight is either impossible or nearly so. If net-positive-EROEI fusion is impossible you could get very large, very complex, and very long lived intelligences but they'd be confined to their own solar systems. -- For completeness I'll throw in two more, though they're ones I often see discussed: (1) They're here, and that's what (some) UFO sightings are. They choose not to make explicit contact for some reason that we are not aware of, and that all visitors have so far shared. This could include an altruistic prime directive (intervention may harm us) or a selfish prime directive (intervention has been shown in the past to produce dangerous results, like post-singularity medieval warrior kingdoms or Nazis). A second reason for lack of explicit contact might be extreme alien-ness. Perhaps they are making contact but are doing so in ways that are so goddamn bizarre that we do not recognize it or culturally process it as such. The UFO literature is full of really wacked-out tales. Maybe some of them are true? http://www.ufoevidence.org/cases/case708.htm http://www.ufoevidence.org/cases/case708.htm Sounds like a joke, right? Or the guy was insane? But imagine a "post-singularity" (for lack of a better term) intelligence that is utterly alien trying to comprehend our TV transmissions and then trying to make contact. Might the attempt not look something like that? Like some kind of weird dada-ist staged imitation of scenes from "I Love Lucy" and "Father Knows Best" with a dash of "The Outer Limits"? Might you not also choose an isolated subject for safety reasons? Like a farmer in a field? Sometimes I wonder if the weirdest most "dada" UFO cases are the most compelling. I would not expect alien contact to look as rational and methodical as meetings between human cultures. We're talking about an intelligence from another biosphere here, or a machine intelligence built by intelligences from another biosphere. Their thoughts might not even be translatable into English outside of the most objective domains like mathematical physics. Consequently unless they staged an undeniably dramatic contact event, we might be likely to dismiss their attempts to communicate as episodes of madness on the part of witnesses. (2) The theists are right. We are the special creations of (or evolution was guided by) a supreme being and are unique. This is actually a variation on the "we are living in a simulation" hypothesis when you think about it.
sanoli 13y ago
I posted this comment on an older thread about the same topic: "If radio signals is the best way for us to detect alien intelligent life, and vice-versa, aren't we doomed to keep quiet then? I mean, how long until we phase strong radio signals almost completely? I mean, has there been any growth in the quantity and power of radio signals since, say, the 80's? It's an honest question, since I don't know, but I see radio declining everywhere, except for, I guess, airplane and naval communication. What else am I missing here? Probably a whole lot, maybe someone could fill me/us in?"
saidur 13y ago
There isn't a paradox. The universe is teeming with life. I've always believed that there was no evidence for ETs and life out there. I thought it was fiction. Then I spent all of last year trying to find legitimate proof of their existence. I just kept my mind open yet skeptical and looked at all the evidence I could find and simply analyzed the data. I was shocked that my conclusion was that ETs exist, they have been visiting us for quite some time, and they are generally benevolent. You don't have to believe anything I say, in fact I wouldn't want you to. All I can ask is that you also spend some legitimate effort doing your research. Here's something to start your path down the rabbit hole: https://www.youtube.com/watch?v=7vyVe-6YdUk https://www.youtube.com/watch?v=7vyVe-6YdUk
shurcooL 13y ago
"Now, everything we know about terrestrial life tells us that life has a natural tendency to expand into all available space." At the same time, it makes sense that more advanced life will try to be more efficient with its use of resources. This is a lot easier to do when you're smaller. Perhaps, they would try to minimize their size, allowing them _expand_ into _smaller_ space. I'm sure this thought has been considered (e.g., see Men in Black 1), but I felt like sharing it anyway.
increment_i 13y ago
Wow, really enjoyed reading the great thoughts on this thread. Similar to what others have said, I think the spectrum of 'intelligence' might be exponentially larger than anything the human mind can comprehend at this point in our development. Since we're at the top of our planet's bio-hierarchy I think we tend to marvel at our own cleverness, yet wonder 'Where are the others like us?" If other lifeforms are around us, they don't necessarily have to attempt to contact us or make themselves known to us in a way we could understand. There are millions of microorganisms around you right now, but they could never 'contact' you or even observe you in any meaningful way.
- tcgv 13y ago
  "Now my own suspicion is that the Universe is not only queerer than we suppose, but queerer than we can suppose." [1] [1]J. B. S. Haldane. Possible Worlds and Other Papers (1927), p. 286
coldcode 13y ago
Reading their equivalent to HN.
dspillett 13y ago
> Where Is Everybody? That might not be the right question, or at least is isn't the only pertinent question. Other quesitons: "why can't we see the ones that are around now" and/or "what happened to the ones that aren't around now". If we are detecting civilisations feom the RF output, then consider how quicly we went from no RF output to nearly blowing ourselves to bits. Many civilisations could have committed suicide in a short space of time too. Many millions of them could have shone breifly and vanished millions of years before we even started looking. That is a tad fatalistic: we haven't managed to wipe ourselves out even though we threatened it to an extent. But there is another good reason why an older civilisation would be difficult to detect: efficiency. As a civilisation's technology improves, unless they find an effectively unlimited energy source, it is likely that they will leak less and less out: communicating point-to-point methods most of the time rather than by broadcast, containing and reusing what would otherwise be waste products of enery production/use. Of course they would never be 100% efficient, but they only need to be efficient enough that by the time the side-effects of their activity reach us they are not descernable amongst the background noise from the stars, black holes and other parts of the cosmos. Evidence of other life could be passing us by right now and our attmepts to detect it are simply insufficient, in fact the more civilisations there are out there the harder the problem could become: the signals from each would interfere making the attempt to spot any one signal amongst the background noise (in part natural noise and in part that from the other signals) that but harder. It is all moot at the moment of course: unless they are on our doorstep, to the point where we couldn't miss them, meaningful communication in our lifetimes is very very unlikely. Of course there are other equally possible explanations, such as us being in a simulation of sorts.
leejw00t354 13y ago
I think the mostly likely reason we don't see evidence for intelligent life in the universe is simply because we don't realize how unlikely it is to evolve intelligence. Maybe there are a lot more evolutionary paths life can take on a world than just something similar to what happened here on Earth. Maybe typically it's unlikely for life to evolve to become much more than plant-like life forms. I'm sure there are species in the universe which have evolved intelligence but I think they're much rarer than we would assume here on our perfect example world, Earth.
FellowTraveler 13y ago
Any sufficiently advanced civilization will have encrypted communications, and thus their broadcasts will appear to be noise.
brianmcconnell 13y ago
Another possibility is that intelligent life is relatively common, but highly technological civilizations are rare. How would human civilization have panned out if we had not been lucky enough to discover huge, easily accessible reserves of petrochemicals? We might have continued to enjoy a population and standard of living comparable to the 1700s, but not progressed to become the energy intensive civilization we are today. One could argue that would not necessarily be a bad thing in the long run. It's also worth remembering that for 99.9% of our existence as a species, we lived on a much smaller energy budget. So maybe that's the norm, and planets where Saudi Arabia scale reserves of free energy are just sitting there for the taking are quite rare. Then, of those that do, what percentage successfully make the transition to become long-term spacefaring civilizations? For a good read on the Fermi paradox, be sure to check out David Brin's The Great Silence.
gtt 13y ago
Thank you, everyone! This is probably the best thread I've read on hacker news in years!
LogicalBorg 13y ago
The universe is teeming with intelligent mimes. They can't wait for us to gesture silently to them through the cosmic void. Oh, the horror.

51 points by obblekk 13y ago

https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CEEQFjAB&url=http%3A%2F%2Fwww.astro.ufl.edu%2F~lebo%2FAST2037%2FFermi's%2520Paradox%2520-%2520Stephen%2520Webb.docx&ei=kMrRUqzyDsX32QW2lIFQ&usg=AFQjCNHKQDX6K8mCoXHHuGCWhE_WHRh3yw&sig2=6okCviy35CLcGaJQAAfOQg https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd... Edit: I'll add one to the above: it might be that there are enough hostile forces, or at least the possibility of enough hostile forces, to make every technologically capable civilization conclude to travel near the speed of light to protect themselves from relativistic bombs. (Objects going very close to the speed of light. Impossible to detect in time to deflect, a form of advanced weaponry.) Each alien civilization sees that there are no observable civilizations and decides that the ones that have existed either died or fled into near-the-speed-of-light vehicles. They rationally conclude to do the same, at least while they advance their technology and search for life. The unfortunate part is that time goes by much faster for us than it does for them, (which negates the advantage that many early civilizations would have had).

exratione 13y ago

To preempt some of the usual thought on this topic: no solution to the Fermi Paradox can rely on every civilization taking a certain direction. It doesn't matter how strong the incentives are for any particular course of action, the numbers (of stars, planets, etc) even in just our galaxy are so very large that even under rare life assumptions there are still going to be an enormous number of civilizations at any given time, never mind over all history. Some of those will have (or will have had) subcultures that generate self-replicating colonies, probes, or whatever. Those visit every stellar system in the galaxy in a very short time frame. Possibly viable solutions include: - We are simulated. - Stochastic colonization leaves long-lasting uncolonized voids at all scales. - Wolves. (Ecological wolves intent on making everything look natural, but since they get to be unitary, they can be as odd as they want to be). But non-wolf Great Filter arguments have the same issues as arguing that all civilizations sublime, or leave, or whatever. There is always going to be someone who doesn't.

MrScruff 13y ago
the numbers (of stars, planets, etc) even in just our galaxy are so very large that even under rare life assumptions there are still going to be an enormous number of civilizations at any given time, never mind over all history. The problem is we have no way of estimating the probability of life emerging given favourable conditions. It could be 1x10^-100 for all we know.
- jjoonathan 13y ago
  Life emerged very early in the geological history of Earth. The probability of this happening is greater under the "P(life|conditions)≈1" model than under the "P(life|conditions)≈0" model. Our historical observations give the "P(life|conditions)≈1" model greater likelihood. It's not exactly proof, but it's enough to convince me.
  - argonaut 13y ago
    Selection bias.
    - jjoonathan 13y ago
      > Selection bias. Elaborate. If you're referring to the anthropic principle, I don't see how it's relevant to my argument.
      - argonaut 13y ago
        Historical observations of sample size 1?
        jjoonathan 13y ago
        Not strictly relevant. If your hypothesis is extreme, a single observation can make its posterior probability small. For instance, suppose that Alice gives you a coin and says "it lands on heads 99% of the time" (hypothesis A) but Bob calls BS and says "it looks like a regular quarter, so it should land on heads 50% of the time" (hypothesis B). You assign prior probabilities of 50% to A,B because on one hand you can't imagine how anyone could engineer a coin to land on heads 99% of the time, but on the other hand Alice is a great engineer, so you don't know what to believe. If you flip the coin a single time and get tails, your experiment strongly supports hypothesis B over A. OTOH, if it landed on heads, A would be weakly supported over B. We started with an even prior, so the posterior probability of A,B are proportional to their likelihoods: P(A|t)≈2% and P(B|t)≈98%, while P(A|h)≈66% and P(B|h)≈33%. Let's say that a typical planet remains habitable for 8b years and it takes 4b years from the emergence of life to the emergence of intelligent life, so according to the anthropic principle life had a 4b year window in which to emerge. Under the model where P(emergence)/time is tiny, the probability of life emerging in the first billion years is ~.25. Under the model where P(emergence)/time≈1, the probability of life emerging in the first billion years is 1. With even priors, the posterior of P(emergence)/time≈1 is 80% and the posterior of P(emergence)/time≈0 is 20%. It's not scientific proof of anything, but it's enough to make me consider alternative explanations for why life is rare.

krisgee 13y ago

Personally I think civilizations tend to undergo a singularity or destroy themselves eventually and the exceptions to those two cases are rare enough that communication becomes exceptionally rare.

alan_cx 13y ago
That is as depressing as it is plausible. Nice that its such a simple theory, but rings more true than any other.
obblekk 13y ago
By singularity, you mean the creation of artificial intelligence? If so, then shouldn't we be encountering these AIs?
- sitkack 13y ago
  No, they would become addicted to pleasure stimulus, their version of digital heroin and become "unproductive"

memracom 13y ago

Why does everyone assume that if life has existed on another planet for a billion or two years, it must necessarily be similar to life on our planet and be intelligent with some sort of civilization? Why could it not be a planet filled with brainless jellyfish and green algae? People forget that our planet has been through several catastrophic events that happened at certain times in our planetary evolution, and on other planets those events did not happen, or happened at different points in their evolution, or those events had a more severe impact. Things like the snowball earth phase, and the comet that triggered the die off of most dinosaurs. Maybe most planets are inhabited by symbiotic colonies of advanced trilobites 20 meters long crawling the ocean floor eating the abundant sponges. Have a look at the wierd and wonderful pre-cambrian life forms that somehow combined to create the kind of animalia that we know today. What triggered that? And earlier, what triggered the abundant bacterial mats to start forming mobile colonies? Sure, life is everywhere in the universe but the trajectory that life took on earth will be exceedingly rare and we may never encounter another such planet even if we develop advanced star travel.

obblekk 13y ago
Part of the Drake equation is multiplying by the probability that intelligent life evolves. Of course we only have one data point, but it seems like intelligence is a pretty good response to many evolutionary pressures and so is likely to come about over time. Of course, this depends on how frequent you think intelligence is. I think most people assume it's very frequent.
millstone 13y ago
We should take your idea and push it farther: We're not looking for life. If we found an advanced civilization of intelligent robots, would we shrug and say "too bad they're not alive?" Of course not. So it's not life we hope to find.
EliRivers 13y ago
Why does everyone assume that... They don't. They really don't. Do you honestly think you're the first person to ever think of this?
13y ago

coenhyde 13y ago

I would say the highest probability is that we're in a zoo. We'd be pretty interesting to watch as a blossoming civilization.

api 13y ago
Given that there are many stars that are far older than the Sun with Earth-like planets, this is not that far-fetched. We have already started setting aside regions of our own planet as nature preserves, so it's not hard to imagine someone incredibly more advanced than us reaching similar philosophical conclusions and doing so on a solar system or star cluster scale. This might also involve an element of self-interest on their part. Perhaps intervention has been shown to produce dangerous results.

thret 13y ago

"Page xx is not part of this book preview" Sigh, I hate crippleware. I do love this paradox though, it makes for enjoyable conversation over a bottle of wine with just about anyone.

sigzero 13y ago

I believe we are it. That said, if there is alien life it could be at the same stage of industrial development that we are and it will be a long long long time before we meet.

soneca 13y ago

Not long ago I read a fiction piece (linked here in HN)that would imagine the world (and universe) in 10^1, 10^2, 10^3, 10^4, 10^5, 10^6... years. In this tale, Earth would have several species achieving intelligence, all of them failing on interestelar colonization, and the last one, the wisest, figured out from the basic physics knowledge they develop, that this kind of travel would be impossible. This basic assumption is very strong for me. Even if one civilization can travel at light speed, the multiple civilizations on our universe right now could be at millions of years of distance one of other.

akkartik 13y ago
Yeah, that's a good one: https://news.ycombinator.com/item?id=6860839 https://news.ycombinator.com/item?id=6860839

twocommas 13y ago

A good overview of the "Great Filter" in the context of the Fermi Paradox: http://en.wikipedia.org/wiki/Great_Filter http://en.wikipedia.org/wiki/Great_Filter

kordless 13y ago
My personal theory is that dark matter is the great filter. We can't see them because they've taken it to a whole another level.

belluchan 13y ago

Enjoying the virtual reality world they made, which is probably better than the real world. If you are smart enough to create a virtual world in which you can do almost anything you wanted, why would you give two shits about the real world. Modern day gaming is the beginning of something much more significant in my opinion.

api 13y ago
I consider this a dark possibility. It means that intelligence, by producing minds capable of hacking their hedonic desires, ends in nothing but a prolonged orgy of complex masturbation.
guard-of-terra 13y ago
Gaming is fun until it bores you. I play from time to time and I certainly would not like to replace more of my life with games. I'm in it not for pleasures but to see what's next and to affect it. Some individuals will remain active in the virtual society. Active and with lots of technical ability.
bloodorange 13y ago
Because the real world has surprised for us (and them) to discover. In search of the unknown, humankind has discovered a lot...
akiselev 13y ago
That may be true for some (many? most?) people, I could think of a couple of reasons: a) Desire to explore nature's imagination instead of that of another human or AI. Perhaps we never hit a limit of computation, but there is an entire expanding, constantly growing in complexity universe out there to understand! b) Even with artificial penalties, I doubt any virtual world could carry the same perceived risk as going out into the real world and risking getting eaten by a black hole or burned by an exploding supernova (assuming of course, you knew of/could tell the difference).
- belluchan 13y ago
  In the future, I think that even when we end up interacting with the real world we'll have a virtual one mapped over it, ala alternate reality stuff. Check out Rainbows End for what I mean there. We can't stop interacting with the real world, but I imagine in the future most people wont. Current boredom is a reflection of our current technology and creative state in virtual worlds, not indicative of what the future will hold, it's only going to get better and while nature is amazing is so many ways human imagination trumps it. Whenever we do see something new we take it and add to it.

whatshisface 13y ago

What if it's easier to build a utopia than a starship? We already have way more money going into entertainment than into space exploration, it's not that hard to imagine that all sentient species eventually learn how to hack themselves into permanent happiness, and then conclude they have no reason to risk death on the final frontier.

sanoli 13y ago
A lot of human, throught humanity's history, had the material means to live a pretty pleasant, labor-free life, and yet chose a different path, away from hedonism. I suppose this will still be true many centuries from now.
- burke 13y ago
  Pretty much any organism that manages to develop the intelligence to build a starship will have a long history of evolution. Their mindset will presumably be guided by ancient evolutionary pressures. For us humans, we're partially motivated by a desire to explore and understand our surroundings. I think it's realistic to assume that at least some subset of aliens should be motivated by the same exploration drive.
akiselev 13y ago
What is the probability of such a utopian society going its entire existence without at least one group of individuals with the resources to go out into the universe pulling the trigger on the decision to risk their lives? This ofcourse requires some projection of our ideas of happiness onto unknown alien beings, but then why not also project boredom? If anything, we have seen that nothing in nature really stays the same. It is ever changing and evolving.
- belluchan 13y ago
  When I predict that VR will trump reality I never mean to imply a virtual happy Utopia or that such a thing was inevitable. Our future might be a virtual dystopia for all I know, but virtual reality is my bet where most intelligent beings end up going. I think virtual worlds > reality would explain the Fermi paradox nicely.

patrickmay 13y ago

I find the argument that we're in a simulation rather compelling: http://io9.com/5799396/youre-living-in-a-computer-simulation-and-math-proves-it http://io9.com/5799396/youre-living-in-a-computer-simulation...

saidur 13y ago
I think you would enjoy Thomas Campbell's work :) https://www.youtube.com/watch?v=fT8LaMrn_MM https://www.youtube.com/watch?v=fT8LaMrn_MM
- tcgv 13y ago
  I really liked his definition of consciousness: "Consciousness is the only thing that is fundamental. Everything else is derived from consciousness, including this physical reality."

api 13y ago

I'll toss another one in: What if net-positive-EROEI controlled fusion is impossible? We have only succeeded in producing nuclear fusion in two ways: atomic bomb primers and net-negative-EROEI reactors. Atomic bombs are technically usable as space propulsion (Google Project Orion), but the max velocities reachable are only on the order of 4-8% the speed of light. At that rate, interstellar travel is severely curtailed to only the closest groups of stars. We're talking over a hundred years to Alpha Centauri if you leave time (and reserve extra mass) for acceleration and deceleration. Net-positive-EROEI controllable fusion is the only power source I know of that could allow anything near practical interstellar flight, so if it's not possible for fundamental physical reasons I'd conclude that interstellar flight is either impossible or nearly so. If net-positive-EROEI fusion is impossible you could get very large, very complex, and very long lived intelligences but they'd be confined to their own solar systems. -- For completeness I'll throw in two more, though they're ones I often see discussed: (1) They're here, and that's what (some) UFO sightings are. They choose not to make explicit contact for some reason that we are not aware of, and that all visitors have so far shared. This could include an altruistic prime directive (intervention may harm us) or a selfish prime directive (intervention has been shown in the past to produce dangerous results, like post-singularity medieval warrior kingdoms or Nazis). A second reason for lack of explicit contact might be extreme alien-ness. Perhaps they are making contact but are doing so in ways that are so goddamn bizarre that we do not recognize it or culturally process it as such. The UFO literature is full of really wacked-out tales. Maybe some of them are true? http://www.ufoevidence.org/cases/case708.htm http://www.ufoevidence.org/cases/case708.htm Sounds like a joke, right? Or the guy was insane? But imagine a "post-singularity" (for lack of a better term) intelligence that is utterly alien trying to comprehend our TV transmissions and then trying to make contact. Might the attempt not look something like that? Like some kind of weird dada-ist staged imitation of scenes from "I Love Lucy" and "Father Knows Best" with a dash of "The Outer Limits"? Might you not also choose an isolated subject for safety reasons? Like a farmer in a field? Sometimes I wonder if the weirdest most "dada" UFO cases are the most compelling. I would not expect alien contact to look as rational and methodical as meetings between human cultures. We're talking about an intelligence from another biosphere here, or a machine intelligence built by intelligences from another biosphere. Their thoughts might not even be translatable into English outside of the most objective domains like mathematical physics. Consequently unless they staged an undeniably dramatic contact event, we might be likely to dismiss their attempts to communicate as episodes of madness on the part of witnesses. (2) The theists are right. We are the special creations of (or evolution was guided by) a supreme being and are unique. This is actually a variation on the "we are living in a simulation" hypothesis when you think about it.

sanoli 13y ago

I posted this comment on an older thread about the same topic: "If radio signals is the best way for us to detect alien intelligent life, and vice-versa, aren't we doomed to keep quiet then? I mean, how long until we phase strong radio signals almost completely? I mean, has there been any growth in the quantity and power of radio signals since, say, the 80's? It's an honest question, since I don't know, but I see radio declining everywhere, except for, I guess, airplane and naval communication. What else am I missing here? Probably a whole lot, maybe someone could fill me/us in?"

saidur 13y ago

There isn't a paradox. The universe is teeming with life. I've always believed that there was no evidence for ETs and life out there. I thought it was fiction. Then I spent all of last year trying to find legitimate proof of their existence. I just kept my mind open yet skeptical and looked at all the evidence I could find and simply analyzed the data. I was shocked that my conclusion was that ETs exist, they have been visiting us for quite some time, and they are generally benevolent. You don't have to believe anything I say, in fact I wouldn't want you to. All I can ask is that you also spend some legitimate effort doing your research. Here's something to start your path down the rabbit hole: https://www.youtube.com/watch?v=7vyVe-6YdUk https://www.youtube.com/watch?v=7vyVe-6YdUk

shurcooL 13y ago

"Now, everything we know about terrestrial life tells us that life has a natural tendency to expand into all available space." At the same time, it makes sense that more advanced life will try to be more efficient with its use of resources. This is a lot easier to do when you're smaller. Perhaps, they would try to minimize their size, allowing them _expand_ into _smaller_ space. I'm sure this thought has been considered (e.g., see Men in Black 1), but I felt like sharing it anyway.

increment_i 13y ago

Wow, really enjoyed reading the great thoughts on this thread. Similar to what others have said, I think the spectrum of 'intelligence' might be exponentially larger than anything the human mind can comprehend at this point in our development. Since we're at the top of our planet's bio-hierarchy I think we tend to marvel at our own cleverness, yet wonder 'Where are the others like us?" If other lifeforms are around us, they don't necessarily have to attempt to contact us or make themselves known to us in a way we could understand. There are millions of microorganisms around you right now, but they could never 'contact' you or even observe you in any meaningful way.

tcgv 13y ago
"Now my own suspicion is that the Universe is not only queerer than we suppose, but queerer than we can suppose." [1] [1]J. B. S. Haldane. Possible Worlds and Other Papers (1927), p. 286

coldcode 13y ago

Reading their equivalent to HN.

dspillett 13y ago

> Where Is Everybody? That might not be the right question, or at least is isn't the only pertinent question. Other quesitons: "why can't we see the ones that are around now" and/or "what happened to the ones that aren't around now". If we are detecting civilisations feom the RF output, then consider how quicly we went from no RF output to nearly blowing ourselves to bits. Many civilisations could have committed suicide in a short space of time too. Many millions of them could have shone breifly and vanished millions of years before we even started looking. That is a tad fatalistic: we haven't managed to wipe ourselves out even though we threatened it to an extent. But there is another good reason why an older civilisation would be difficult to detect: efficiency. As a civilisation's technology improves, unless they find an effectively unlimited energy source, it is likely that they will leak less and less out: communicating point-to-point methods most of the time rather than by broadcast, containing and reusing what would otherwise be waste products of enery production/use. Of course they would never be 100% efficient, but they only need to be efficient enough that by the time the side-effects of their activity reach us they are not descernable amongst the background noise from the stars, black holes and other parts of the cosmos. Evidence of other life could be passing us by right now and our attmepts to detect it are simply insufficient, in fact the more civilisations there are out there the harder the problem could become: the signals from each would interfere making the attempt to spot any one signal amongst the background noise (in part natural noise and in part that from the other signals) that but harder. It is all moot at the moment of course: unless they are on our doorstep, to the point where we couldn't miss them, meaningful communication in our lifetimes is very very unlikely. Of course there are other equally possible explanations, such as us being in a simulation of sorts.

leejw00t354 13y ago

I think the mostly likely reason we don't see evidence for intelligent life in the universe is simply because we don't realize how unlikely it is to evolve intelligence. Maybe there are a lot more evolutionary paths life can take on a world than just something similar to what happened here on Earth. Maybe typically it's unlikely for life to evolve to become much more than plant-like life forms. I'm sure there are species in the universe which have evolved intelligence but I think they're much rarer than we would assume here on our perfect example world, Earth.

FellowTraveler 13y ago

Any sufficiently advanced civilization will have encrypted communications, and thus their broadcasts will appear to be noise.

brianmcconnell 13y ago

Another possibility is that intelligent life is relatively common, but highly technological civilizations are rare. How would human civilization have panned out if we had not been lucky enough to discover huge, easily accessible reserves of petrochemicals? We might have continued to enjoy a population and standard of living comparable to the 1700s, but not progressed to become the energy intensive civilization we are today. One could argue that would not necessarily be a bad thing in the long run. It's also worth remembering that for 99.9% of our existence as a species, we lived on a much smaller energy budget. So maybe that's the norm, and planets where Saudi Arabia scale reserves of free energy are just sitting there for the taking are quite rare. Then, of those that do, what percentage successfully make the transition to become long-term spacefaring civilizations? For a good read on the Fermi paradox, be sure to check out David Brin's The Great Silence.

gtt 13y ago

Thank you, everyone! This is probably the best thread I've read on hacker news in years!

LogicalBorg 13y ago

The universe is teeming with intelligent mimes. They can't wait for us to gesture silently to them through the cosmic void. Oh, the horror.