No ETs Is Good News for Humanity's Future?

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Philosopher and director of the Future of Humanity Institute at Oxford University, Nick Bostrom has a fascinating article in the current issue of Technology Review in which he hopes that Mars turns out to be a barren lifeless rock. Why? Because that would mean that the "Great Filter" is more likely behind us than ahead of us. So far the Search for Extraterrestrial Intelligence (SETI) has been a dud. Bostrom argues that there may be two explanations for this.

First, the evolution of intelligent life may be extremely unlikely despite the fact that the galaxy's stars are orbited by billions and billions of planets. Some "filter," say the development of prokaryotic eukaryotic cells, must be passed before intelligence evolves. If intelligence is extremely hard to evolve that would explain why we have encoutered no ETs nor overheard them chattering among the stars.

The alternative explanation for the silence of skies is more sobering. As Bostrom explains it:

The more disconcerting hypothesis is that the Great Filter consists in some destructive tendency common to virtually all sufficiently advanced technological civilizations. Throughout history, great civilizations on Earth have imploded–the Roman Empire, the Mayan civilization that once flourished in Central America, and many others. However, the kind of societal collapse that merely delays the eventual emergence of a space-colonizing civilization by a few hundred or a few thousand years would not explain why no such civilization has visited us from another planet. A thousand years may seem a long time to an individual, but in this context it's a sneeze. There are probably planets that are billions of years older than Earth. Any intelligent species on those planets would have had ample time to recover from repeated social or ecological collapses. Even if they failed a thousand times before they succeeded, they still could have arrived here hundreds of millions of years ago.

The Great Filter, then, would have to be something more dramatic than run-of-the mill societal collapse: it would have to be a terminal global cataclysm, an existential catastrophe. An existential risk is one that threatens to annihilate intelligent life or permanently and drastically curtail its potential for future development. In our own case, we can identify a number of potential existential risks: a nuclear war fought with arms stockpiles much larger than today's (perhaps resulting from future arms races); a genetically engineered superbug; environmental disaster; an asteroid impact; wars or terrorist acts committed with powerful future weapons; super­intelligent general artificial intelligence with destructive goals; or high-energy physics experiments. These are just some of the existential risks that have been discussed in the literature, and considering that many of these have been proposed only in recent decades, it is plausible to assume that there are further existential risks we have not yet thought of.

The study of existential risks is an extremely important, albeit rather neglected, field of inquiry. But in order for an existential risk to constitute a plausible Great Filter, it must be of a kind that could destroy virtually any sufficiently advanced civilization. For instance, random natural disasters such as asteroid hits and supervolcanic eruptions are poor Great Filter candidates, because even if they destroyed a significant number of civilizations, we would expect some civilizations to get lucky; and some of these civilizations could then go on to colonize the universe. Perhaps the existential risks that are most likely to constitute a Great Filter are those that arise from technological discovery. It is not far-fetched to imagine some possible technology such that, first, virtually all sufficiently advanced civilizations eventually discover it, and second, its discovery leads almost universally to existential disaster.

So where is the Great Filter? Behind us, or not behind us?

If the Great Filter is ahead of us, we have still to confront it. If it is true that almost all intelligent species go extinct before they master the technology for space colonization, then we must expect that our own species will, too, since we have no reason to think that we will be any luckier than other species. If the Great Filter is ahead of us, we must relinquish all hope of ever colonizing the galaxy, and we must fear that our adventure will end soon–or, at any rate, prematurely. Therefore, we had better hope that the Great Filter is behind us.

What has all this got to do with finding life on Mars? Consider the implications of discovering that life had evolved independently on Mars (or some other planet in our solar system). That discovery would suggest that the emergence of life is not very improbable. If it happened independently twice here in our own backyard, it must surely have happened millions of times across the galaxy. This would mean that the Great Filter is less likely to be confronted during the early life of planets and therefore, for us, more likely still to come.

You really should treat yourself to Bostrom's thoughtful article "Where Are They?: Why I hope the search for extraterrestrial life finds nothing."

Hat tip to Darrell Brookstein.

NEXT: Only Two of Them Got Impeached? Really?

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  1. It is not far-fetched to imagine some possible technology such that, first, virtually all sufficiently advanced civilizations eventually discover it, and second, its discovery leads almost universally to existential disaster.

    It’s the Stuckey’s Pecan Log Roll.

  2. This is a very cool subject, there should be much more comments than this.

    This subject should interest the God enthusiasts

    The gun control argument enthusiasts.

    The Sci Fi enthusiasts

    The Aliens are Already here and control our government in cooperation with the Jews enthusiasts.

    The IllegalAlien enthusiasts.

    Lots of topics to be discussed here. Maybe this should be the Friday fun thread or something (but without the music).

  3. Some “filter,” say the development of prokaryotic cells, must be passed before intelligence evolves.

    Almost certainly you mean eukaryotic cells, not prokaryotic cells.

  4. I’ll offer a third possible explanation as to why we haven’t encountered alien intelligence – maybe other intelligent species don’t share our curiosity or motivations. Why would an intelligent species necessarily be interested in locating other intelligent species? Or perhaps, like us, they made a few unsuccessful preliminary attempts, and just gave up and invested their resources elsewhere.

    Even if we located an intelligent species a few hundred light-years away, even a rudimentary conversation would take hundreds of years to complete. Perhaps other species, recognizing those constraints, have decided to concentrate their efforts on more fruitful pursuits…

  5. The gun control argument enthusiasts.

    Huh?

    Why?

  6. I’ll offer a third possible explanation as to why we haven’t encountered alien intelligence – maybe other intelligent species don’t share our curiosity or motivations.

    From TFA…

    …even if most advanced civilizations chose to remain nonexpansionist forever, it wouldn’t make any difference as long as there was one other civilization that opted to launch the colonization process: that expansionary civilization would be the one whose probes, colonies, or descendants would fill the galaxy. It takes but one match to start a fire, only one expansionist civilization to begin colonizing the universe.

  7. If the super disaster is ahead of us and there’s nothing we can do – hell, keep the superweapons, keep the guns, keep the superbugs because THERE’S NOTHING WE CAN DO!!!

  8. Other Matt,

    NRA. National Raygun Association. Dedicated to keeping doomsday devices firmly in the hands of mad scientists to ward off alien attackers.

  9. A more optimistic hypothesis is that we can’t see or hear all the bustling, chattering ETs around us because they’re all using Krasnikov tubes.

    This, then raises an interesting question. Are there such Krasnikov Tubes connecting star systems in our neighbor hood of the galaxy? How could they be detected at interstellar distances? Would they have any distinctive physical properties (like deflection of light passing near or through them) that would constitute a unique detection signature?

    At least, the existence of Krasnikov Tubes between the stars might provide a neat solution to the Fermi Paradox. We get no interstellar visitors because there is no Krasnikov Tube coming to the Solar System, so it its too inconvenient. We receive no interstellar communications because all such communications are beamed through Krasnikov Tubes, so that the sender does not have to wait years or centuries for an answer.

  10. The Fermi Paradox page on wikipedia is surprisingly informative.

  11. Other Matt,

    As gun technology evolves, some reasoning for a central planning committee to prevent the masses from technology and knowledge that some member of the hoi polloi would misuse and cause the end of humanity.

    Not really the banning of your six shooter, but generally the same theme.

    The masses cannot be trusted with destructive power. Nor the knowledge to make such. Somebody smart needs to be in control and protect us from the irresponsible among us.

    That is basically the logic I see in the gun control argument, and as technology improves the argument increases to other things.

  12. Gimmie a break! They discovered that I am not in the new GTA IV and are staying home.

  13. Extraterresirial intelligences? Bah. Fermi’s paradox was solved shortly after being voiced.

    “They are among us, but they call themselves Hungarians.”*

    *Leo Szilard

  14. even if most advanced civilizations chose to remain nonexpansionist forever, it wouldn’t make any difference as long as there was one other civilization that opted to launch the colonization process: that expansionary civilization would be the one whose probes, colonies, or descendants would fill the galaxy.

    Even so, it doesn’t necessarily follow that this colonization would’ve already happened and reached far enough for us to notice it.

    And there’s all sorts of other things to consider as well: perhaps there’s a race out there exponentially more intelligent than us, but they have no technology because they’re an underwater species who thus could never use fire and then discover how to work metal ores. Maybe they evolved on a planet that simply doesn’t have enough metallic ore to make spacefaring craft. Maybe they lack manipulative limbs.

    But then, I never found anything paradoxical about Fermi’s paradox anyway.

  15. This is all a matter of perspective.

    From one point of view, why just one Great Filter? You may ask which one is the greatest, but if they have comparable likelihoods of causing extinction, there is little reason to call the 70% extincter the Great Filter over the 60% extincter.

    Another important perspective is that the Great Filters need not be unrelated. For example, by barely passing one Filter, we may have been better prepared to pass the next Great Filter.

    Mars provides an excellent scenario for this. If the currently dominant Terran life came from Mars, maybe it was hardier than any life that developed on Earth. Maybe the two-planet scenario allowed the Martian life strain to survive the Great Filter of Mars decline and a Great Filter that Terran life would have failed.

    So, while life may develop rather easily around the universe, it may be an even more unlikely scenario, one that our life strain has endured, that eventually leads to intelligence. And life on Mars may be a critical part of that scenario.

  16. Naga Shadow said it shorter and simpler than I did.

  17. Consider the implications of discovering that life had evolved independently on Mars…This would mean that the Great Filter is less likely to be confronted during the early life of planets and therefore, for us, more likely still to come.

    Uh, except that on Mars it would have been confronted early. He just contradicted himself.

    If Mars had life, the Great Filter killed it early, and we obviously made it past it.

    While very interesting stuff, it doesn’t change the fact that the universe is so damned huge that finding anything in it is a monumental task. I would bet just about anything there is life out there. I would bet a lot that there are other intelligent being out there. There are so many worlds and systems for the possibility of life to evolve that it’s got to happen, many times.

    Just because we haven’t picked up coherent EMF waves yet doesn’t mean jack shit.

  18. But then, I never found anything paradoxical about Fermi’s paradox anyway.

    The point of Fermi’s “paradox” is that, among billions of worlds and past billions of years, any single civilization that was capable of it should have colonized the 100,000 light year diameter galaxy. Pointing out individual examples of civilizations that can’t or won’t become space faring does nothing to refute that.

  19. Or the speed of light is impossible to overcome making space travel from star to star impossible, though fun for sci fi. Same with interstellar communication too.

    Or intelligent life through evolution is not common at all. Our instance on Earth is a fluke accident/mutation that was/is successful.

    Then there’s bias. Because we exist, we have a bias that intelligent life must exist elsewhere and it must be relatively common. We have a bias to explain how “easy” intelligent life is (Drake equation has 7 variable and assumptions with them)

  20. Even so, it doesn’t necessarily follow that this colonization would’ve already happened and reached far enough for us to notice it.

    It doesn’t necessarily follow, but on the time scale of the universe it is extremely likely, unless intelligent life is very, very rare indeed.

    Say you have a single expansionist spacefaring species. Just one. It develops extremely crude interstellar travel, and has the capacity to move to a new star system and colonize it once every 1000 years.

    That would mean that after a billion years, it would inhabit 2 to the power of 1 million solar systems.

    I don’t even know how to write a number that big.

    So for the aliens to not have shown up, we would have to be the first intelligent species in our galaxy. All the stars that produced solar systems before the sun even existed would have had to produce none. Not one.

    Personally, I think the filter is computer technology. If we assume that a living intelligence would be mortal [there is no reason in evolutionary terms to develop immortality, and a few good reasons not to] and would be able to have positive and negative experiences, it becomes extremely likely that such an intelligence will file itself away in virtual environments that it can completely control as soon as it has the technology to do so. This technological level may roughly correspond with the level that allows interstellar travel. This would mean that no aliens have shown up because they’re too busy living in alien porn environments on their core planets.

    Again, though, this leaves us with the “you only need one species to not do that” problem.

  21. innominate: Yes, that’s what I meant. Typing too fast. Fixed. Thanks much.

  22. ed: I believe you will find that Bostrom discussed exactly the observational bias you mention in his article.

  23. Fermi’s Paradox really boils down to a handful of assumptions:

    Galaxy spanning aliens, if they exist, would:

    1) Have some form of communication or travel we’d notice or:
    2) Be here, taking over our nice lovely system.

    There’s a rather large number of possibilities, starting with “Colonization takes a long time” to “They know we’re here and don’t like to slum” to “We wouldn’t freakin’ notice them if they sat in front of us and screamed”.

    It’s also entirely possible we’re alone. I don’t think it matters, unless we find out that we’re sharing the galaxy with the Gbaba.

  24. Uh, except that on Mars it would have been confronted early. He just contradicted himself.

    If Mars had life, the Great Filter killed it early, and we obviously made it past it.

    His point is that if you don’t find any sign of life at all, then that gives more evidence of filters prior to life even originating. So we have passed those as well as whatever extinction filters took care of your presumptive Martian life.

    If you want to humanity to have made it through more filters in its past, the less life you see elsewhere, the more inductive evidence you have.

  25. It develops extremely crude interstellar travel, and has the capacity to move to a new star system and colonize it once every 1000 years.

    Or interstellar space travel just isn’t feasible for our type of living creature. And when I say feasible, I don’t just mean speed of light restrictions, radiation, length of travel, fuel source, food source, etc. I also mean cost-effective.

    It may be that it never becomes cost-effective to colonize another solar system, even if it is possible. Theoretically, we could probably make a ship that would get some living people to Alpha Centauri in a 1000 years. Of course, we would probably have to devote the entire world’s resources to it, which is ludicrous, and it could still fail on its way.

  26. Life capable of traveling between stars in no way has to resemble us or have problems that resemble ours.

    The idea that a greater filter like global terrorism or super bugs or created black holes ending us all is pretty far fetched….but still remotely in the realm of possibility. The idea that such a filter would exist for all possible forms of life capable of one day space travel is totally absurd.

    The inability for us to spot life outside the earth is explained one of two way…we suck and do not have the ability to detect it or we are all alone. The third option that everything kills itself before it can travel between stars is idiotic on its face.

  27. The point of Fermi’s “paradox” is that, among billions of worlds and past billions of years, any single civilization that was capable of it should have colonized the 100,000 light year diameter galaxy.

    *If* we assume that this civilization was not merely capable but also willing. *And* in our own galaxy rather than a few galaxies over. *And* that with the entire galaxy at their disposal, they think it’s worth checking out the solar system of a minor yellow star orbited by a few unremarkable planets.

    Hell, maybe the aliens did a drive-by near Pluto two centuries ago, didn’t detect any radio transmissions coming out of our solar system, and figured there was nothing interesting here. Maybe they came by 60 million years ago and had no interest in a primitive planet whose dominant species were a bunch of big stupid reptiles.

    For that matter, maybe the air around is is filled with alien communications this second, but we don’t know about it for the same reason a Stone Age man taken out of his time and dropped in a modern jungle would have no idea that thousands of radio and TV broadcast transmissions were filling the air all around him: we don’t have the technology to pick it up.

    Fermi’s paradox is only a paradox if you take a LOT of assumptions and elevate them to the status of “truths.”

  28. Or maybe we are off limits to the inter-gallactic confederation of planets or whatever it is called. No one is allowed to visit, no one is allowed to call.

    More likely, of course is what ed said about the impossibility of faster than light travel making a journey to see us less likely than otherwise. Just as time travel would appear to be impossible since no one ever visits from the future.

  29. There’s nobody else because Bersekers got to them. Or The Inhibitors did. Or the Omega Clouds.

  30. The Fermi Paradox page on wikipedia is surprisingly informative.

    And yet according to them forced conscription in the US ended not because of the Gates commission but cuz the hippies were just so damn effective….go figure.

    Wikipedia – The internet encyclopedia great at explaining extraterrestrial life yet terrible at documenting recent US history.

  31. TTere is no reason to look for intelligent life elsewhere when it cannot be shown to exist here.

    Even if we found it, would we recognize it? Do ants recognize humans as a superior intelligence?

  32. *If* we assume that this civilization was not merely capable but also willing. *And* in our own galaxy rather than a few galaxies over. *And* that with the entire galaxy at their disposal, they think it’s worth checking out the solar system of a minor yellow star orbited by a few unremarkable planets.

    It’s not “this civilization….” It’s “any civilization” out of the billions of stars in the galaxy and billions of years the galaxy has been around.

    Fermi’s paradox is only a paradox if you take a LOT of assumptions and elevate them to the status of “truths.”

    It is a purely probabilistic argument. Neither assumptions nor “truths” are required.

    The evolution of interstellar civilizations must be extremely, extremely rare.

  33. There’s nobody else because Bersekers got to them. Or The Inhibitors did. Or the Omega Clouds.

    Wrong Berzerk

    http://en.wikipedia.org/wiki/Berzerk

    Kill the Humanoid! Kill the Humanoid!

  34. Along the lines of what ed said, maybe we aren’t intelligent enough to identify other intelligent life forms.

  35. It may be that it never becomes cost-effective to colonize another solar system, even if it is possible. Theoretically, we could probably make a ship that would get some living people to Alpha Centauri in a 1000 years. Of course, we would probably have to devote the entire world’s resources to it, which is ludicrous, and it could still fail on its way.

    If world GDP were to grow at 4% per year for the next century, our progeny in 2108 could send this ship to Alpha Centauri at the cost of 2% of the world’s resources.

  36. It is a purely probabilistic argument. Neither assumptions nor “truths” are required.

    No, because the probability rests on the assumption that such species not only exist, but share our motivations for colonization AND would decide “if we’re capable of colonizing every inch of the galaxy, then by God we will” AND would leave signs of themselves which we would be capable of recognizing.

  37. @MikeP

    It takes but one match to start a fire, only one expansionist civilization to begin colonizing the universe.

    Yes, but that assumes that the civilizations with the motivation to colonize are also the ones with the means. We have the motivation (kind of). We don’t (yet, if ever) have the means.

    And how common is that motivation among intelligent species? Here, there are several relatively intelligent species – dolphins, whales, several species of apes – but none of them have shown any particular interest in developing inter-species relationships with each other, let alone with us. Usually, they try to stay out of our way! Nor do they seem to have particularly expansionist tendencies, other than simply defending their own territory.

    And another possibility – expansionist tendencies are exactly the Great Filter Bostrom refers to. A desire to expand will usually result in war and aggression when the expansion conflicts with somebody (or something) else’s claim to a territory. We may have plenty of intelligent neighbors who are the non-expansionist dolphin types.

  38. OK, OK. I will grant to the Students of Objectivism that Rand was the ultimate expression of intelligence in the known universe, but that evolutionary path was a dead end as she did not procreate and despite her naming Leonard Peikoff as her “intellectual heir”, he inherited none of her intelligence and has shown himself to possess the intelligence of Eddie Willers, which is nothing to write back to Vulcan about.

  39. Ultimately, we may just be underestimating the vastness of the universe. I’m not sure I buy the ‘Great Filter’ theory, if for no other reason that it smacks of predestiny. Ie, your society will die, eventually, and there’s nothing you can do about it.

    If anything, space colonization itself leads to some interesting ‘filters’, at least in the traditionaly way we view it. Once a colonizing group covers a vast enough distance, communication with them becomes nigh impossible. Unless, as Stevo Darkly mentioned above, they’re using some sort of fantastical system that we’re simply not even tapped into.

  40. This is how many stars there are in the galaxy:

    300,000,000,000

    This is how many years the galaxy has been around:

    8,000,000,000

    What is the probability that every single intelligent civilization that ever evolved in that time in that space meets the non-expansionist criteria?

  41. Speaking of the continuing cycles of civilization’s rise and fall in various parts of this world: Since it only seems to have taken five or six thousand years for our particular civilization to go from scrabbling in the dirt to sending probes that scoop up the dirt on other planets, and since humans were around for tens of thousands of years before that, it seems improbable that great civilizations, perhaps even highly technological ones, never arose in our distant past — or, for that matter, that intelligent creatures that came before us (velociraptor-type saurians, for example) didn’t establish great civilizations in the millions of years before humans came onto the scene.

    Why is evidence of such advanced civilizations apparently absent from the archaelogical and fossil records? Were all the products of any such earlier society bio-degradable? Were the more permanent artifacts made so much earlier that geological and meteorological processes have worn them away, destroyed them outright, or buried them so deep that we may never find them? Would we even recognize surviving artifacts of a truly advanced technology?

    Back in the days when we could tell ourselves that humans were the unquestioned pinnacle of evolution (or, if you prefer, God’s chosen handiwork, entitled to dominion over the planet), it was easier to assume that, once the requisite level of intelligence was reached, we took a long time — punctuated by stumbles and falling back — to reach the brink of space travel. But now science suggests many things that makes that idea harder to swallow, for example:

    1. Aborigines have been in Australia for 50,000 years or more — ten times longer than it took for countless civilizations to rise, fall, and eventually produce our own. Did the aborigines simply never approach our level of technological achievement, or did they long ago surpass it and their society then proceed in a different direction?
    2. Several other species (gorillas, chimps, parrots, cetaceans, cephalopods, e.g.) have high levels of intelligence, including apparent ability to communicate, make and use tools, and engage in feats of memory and reasoning that we thought could be achieved by humans alone.
    3. Fossil evidence leaves open the possibility that at least latter saurians might have been more intelligent, dexterous, and vigorous than popular imagination holds.
    4. Examination of ruins such as the Sphinx indicates greater age than we had supposed — in this case, 12,000-14,000 years or even older. Underwater terraces off Japan may date from between 8,000 and 10,000 years ago; the geometric regularity of the “structures” doesn’t prove, yet tantalizingly indicates, that they are artificial, and if so, were constructed when that area was above water.
    5. Recent evidence of Neanderthal society and intelligence indicates a species that was a lot more similar to us than we had previously supposed; also, that Neanderthal survived alongside “modern-design” humans for a lot longer than we used to believe. Given that, their apparently total disappearance (both in the archaelogical and genetic records!) is a huge mystery.

    My point is not to engage in unsupported speculation, but simply to observe that the state of intelligence in pre-historic times was considerably more complex than most people understand, and that there has been plenty of time for multiple species to attain significant civilizations and/or leave enduring artifacts behind, several times over. Yet we find (or recognize) almost nothing, and the meaning of what we do find seems very unclear and ambiguous.

    If, with all of our achievement and technology, we cannot approach, much less achieve, certainty about the development of intelligence and civilization on our own planet, I’m fairly doubtful that we’ll ever encounter alien intelligence, or even recognize it, if we do.

    I am told that there are groups of people who study how to create enduring artifacts with warning messages on them, to alert future beings to the presence of our hazardous waste (e.g., radioactive waste from nuclear power plants). I hope that this line of inquiry will someday lead to methods, by which we can examine ruins, fossils, anomalous geologic formations, and other remnants of past societies or creatures, to finally realize just how much they knew and when. Of course, at that point, we will ask the same question we are asking about ET: Why are they not (still) here? The answers may put us closer to an understanding of the nature of the “Great Filter.”

  42. What is the probability that every single intelligent civilization that ever evolved in that time in that space meets the non-expansionist criteria?

    How can anybody possibly answer that, when we know nothing of any intelligent species except our own? If you were talking about different human civilizations, that would be one thing: our cultures are different but our biologies and biological motivations are the same. But you can’t assume this holds true for aliens.

  43. I honestly hope that there are ETs, because I honestly hope that we’re not as good as it gets…

  44. I’ve always figured we were just backwards in comparison to the rest of the galaxy. We get some visits for special National Galactographic investigations of primitive societies; otherwise, they just leave us alone. To stew in our boringly primitive ways.

    As for SETI, the window in which civilizations rely on radio communications may be quite short.

  45. 1. Aborigines have been in Australia for 50,000 years or more — ten times longer than it took for countless civilizations to rise, fall, and eventually produce our own. Did the aborigines simply never approach our level of technological achievement, or did they long ago surpass it and their society then proceed in a different direction?

    I’ve always read that humans didn’t make the jump from hunter-gatherer to agriculture until we had to, because our population reached a point where the land wasn’t enough to sustain hunter-gatherer lifestyles. Farming produces a lot more food per acre, but a primitive farmer’s life sucks in many ways compared to that of a hunter-gatherer. I don’t think the Aboriginal population reached the point where it got too big to sustain itself through the old tried-and-true methods, did it?

    I also think Jared Diamond was onto something in Guns, Germs and Steel: the sophistication of your technology is dependent in part on what natural resources you have available.

  46. The masses cannot be trusted with destructive power. Nor the knowledge to make such. Somebody smart needs to be in control and protect us from the irresponsible among us.

    You can argue that one either way. Once “someone” is charged with repressing “destructive” technology they ban so many things that spaceflight becomes impossible. Just as likely, the centralized social control prevents so much experimentation and development that technology stagnates and the economy breaks down. Centralized control always sucks.

    The gun control argument enthusiasts.

    Huh? Why?

    Throughout history where has technological progress come from? Governments or individuals?

    The right to keep and bear arms could be the Great Filter. If government manages to disarm individuals and take control of a society prior to a level of space flight that makes colonization possible, the society will never develop such technology. Governments aren’t prone to let their peons escape.

    It’s reasonable enough to make a good story plot.

  47. An existential risk is one that threatens to annihilate intelligent life

    Well, joe’d still be around at least.

    The gun control argument enthusiasts.

    Huh? Why?

    Throughout history where has technological progress come from? Governments or individuals?

    The other humorous references make sense. I’m not averse to making fun of stereotypes, I just honestly don’t understand where gun enthusiasts fit in that picture. I guess I must be dense today.

  48. “Even if they failed a thousand times before they succeeded, they still could have arrived here hundreds of millions of years ago.”

    Oh, they’ll be here alright. Just as soon as they discover what fun a weekend in Branson can be.

  49. I’ve always read that humans didn’t make the jump from hunter-gatherer to agriculture until we had to, because our population reached a point where the land wasn’t enough to sustain hunter-gatherer lifestyles.

    YA what ever it is you are reading please stop, cuz that is complete bullshit.

  50. Joshua, have you an explanation more precise than “that is complete bullshit?”

  51. Ya know, there is the possibility of advanced civilizations normally forming closer to the core of galaxies, where they are blinded to things outside of their solar systems from all the noise surrounding them.

    We might just be unique in that in that respect and not much else.

  52. Doesn’t matter. The expanding universe is taking each world farther away from its neighbors. You may as well look up into the night sky and wave goodbye as they recede from view and reach.

  53. The idea that such a filter would exist for all possible forms of life capable of one day space travel is totally absurd.

    I’m with joshua corning here. Civilizations are by their nature robust. And with the multitude and variety of civilizations that could arise in billions of worlds and billions of years, the same small set of later stage filters could not destroy them all.

    Besides, once a civilization colonized anywhere outside the range of the filtering mechanism — such as another star system — then the isolation would be protection enough while the communication from the extinguished population to the survivors would be education Not To Do That.

  54. Guy Montag,

    In other words… we’re hicks with no cell service. Great. I live in Kentucky on Earth and Kentucky in the Milky Way.

  55. ed,

    Doesn’t matter. The expanding universe is taking each world farther away from its neighbors. You may as well look up into the night sky and wave goodbye as they recede from view and reach.

    But the galaxies and clusters are not spinning apart.

    SugarFree,

    Guy Montag,

    In other words… we’re hicks with no cell service. Great. I live in Kentucky on Earth and Kentucky in the Milky Way.

    Um, if you mean that to the converse of ‘they are inner-city dopes who can’t see past the end of the block’ then maybe ya got something there 🙂

  56. Besides, once a civilization colonized anywhere outside the range of the filtering mechanism — such as another star system — then the isolation would be protection enough while the communication from the extinguished population to the survivors would be education Not To Do That.

    So these aliens are enough like us to share our expansionist tendencies, yet different enough to NOT share our abysmal tendency to refuse to learn from history?

  57. @ LarryA

    That reminded me of an old Asimov novel, The End of Eternity except it was space travel that was suppressed.

    http://en.wikipedia.org/wiki/The_End_of_Eternity

    My favorite SF reason why the Fermi paradox was wrong is Harry Turtledove’s The Road Not Taken, in which it turns out interstellar travel is really easy (Iron age tech, IIRC) and there’s no reason for a species to develop their technology after they go into space – so the only species with radio, electricity and the like is us.

    http://en.wikipedia.org/wiki/The_Road_Not_Taken_(short_story)

  58. D’oh, close tag! Close tag!

  59. What about the idea that when a civilization gets sufficiently advanced that going to the stars just doesn’t seem worth it anymore? I’m thinking specifically of the matrioshka brain concept.

    Nothing says that we would recognize an advanced stellar-travelling civilization for what it is either. Is physical travel even necessary to explore the universe for a highly advanced civilization?

  60. Maybe a truly advanced civilization doesn’t use broadcast but only uses cable TV. Wonder how they solve the customer service problems.

  61. The Great Silence could also be due to gamma ray burst extinctions.

  62. I have to admit that this Bostrom feller presents a very solid argument. I cannot find a hole in it, but I hope that he is mistaken. I would prefer to see universe full of life. He may yet be proven mistaken, he even presented one possibility himself: the existence of community of intelligences much more advanced than ours and aware of our existence, but who would not contact us until we are sufficiently advanced. It is kind of like federation of planets and primary directive of non-interference in Star Trek universe. There are too many unknowns in this equasion.

  63. Of course it could simply be that all intelligent life that might try to travel great distances through space destroy them selves by creating micro black holes or strangelets in their super-colliders.

    Maybe all planets reach stage 13 and, in looking for the mass of the Higgs Boson particle, become condensed into a pea sized object. And if you get that reference you’ve also wasted a certain amount of time in front of the telly.

  64. The third option that everything kills itself before it can travel between stars is idiotic on its face.

    I like your optimism Josh

  65. In 4.6 billion years of earth’s history, there is evidence of only one self-aware intelligent species capable of language use and advanced tool manipulation. And that species has existed for less than 100 thousand years, a blink of the eye in geological time. Barring evidence to the contrary it’s just wishful thinking to think there’s intelligent life out there the way we understand it. At least in this galaxy. The Universe is probably teeming with life, but very little of it more advanced than birds or cephalopods.

  66. I’m going with the libertarian option. I think the Great Filter is that by the time a civilization reaches the point of space travel, they’ve created a government that’s so shitty, they can’t accomplish anything else. America was a great country until we reached the moon.

  67. The martians and others have not contacted us in response to our outgoing messages because our technology is a step ahead of theirs and they failed to invest in the “box” to transform the signal into one they could use.

    Oh. and because the signal degrades before it gets any wheres near other stars.

  68. Yes, I think that your scenario is a very distinct possibility. The filter does not have to be a nuclear or bacteriological holocaust. It could be that once civilization reaches certain level of technological advancement when their material needs are met and virtual reality can satisfy all their needs for stimulation; civilization just looses all motivation to do anything else. It just masturbates itself to death.
    I hope that this is not the case.

  69. Vanya’s point is interesting, and raises the possibility that the filter is a reverse filter – it’s not that Earth made it through a filter and was lucky, but that Earth got whacked by filters other planets did not have.

    Maybe the conditions for life on Earth are harsher than elsewhere, and that’s why intelligence developed.

    There could be lots of planets with life, but with more stable climates than the Earth, and therefore a lot of stable life forms that never evolve intelligence.

  70. Vanya:

    Nothing more advanced than cephalopods? Be afraid, be very afraid. If it weren’t for their short lifespans we’d probably be competing with a bunch of Cthulus for seating at Red Lobster.

  71. The Great Silence could also be due to gamma ray burst extinctions.

    I blame Klaus Kinski for it, but you might be right.

    And those will stop someday. Then the universe will fill up with live XXX girls.

    We got here at the wrong time, like showing up at the nude beach during a blizzard in January.

    They’ll get here someday, and we’ll be dead.

  72. We got here at the wrong time, like showing up at the nude beach during a blizzard in January.

    They’ll get here someday, and we’ll be dead.

    Naw, just means we got time to slather on some sunscreen, get our cabanas ready, and make a few drinks.

  73. Also, yeah, apparently they are already here, we need a stronger filter:

    http://jordanmaxwell.com/

  74. kwais,

    Excellent example of the “Crazier the person, uglier the website” maxim. Of course, blogs are mostly homogenized, so the maxim is fading.

  75. That reminded me of an old Asimov novel, The End of Eternity except it was space travel that was suppressed.

    Actually I was thinking of Pournelle’s Promethius Award winner Fallen Angels, where the suppression comes barely too late to prevent colonization. His stories featuring the CoDominium share the technology-suppression-for-mankind’s-benefit theme.

    My favorite SF reason why the Fermi paradox was wrong is Harry Turtledove’s The Road Not Taken

    Also one of my favorites.

    I just honestly don’t understand where gun enthusiasts fit in that (individual/government) picture.

    Consider that gun rights has become an “individual right” v “collective right” controversy.

  76. I’m with Ilya–all civilizations stop expanding and stop sending out signals when they can adequately replace reality with their own superior versions thereof.

  77. SugarFree, I like that maxim. I am going to have to quote that around.

  78. It could be that once civilization reaches certain level of technological advancement when their material needs are met and virtual reality can satisfy all their needs for stimulation; civilization just looses all motivation to do anything else. It just masturbates itself to death. Ilya, that’s sadly plausible – it’s basically the “Idiocracy” scenario.

  79. So I was watching Dr Who on the Sci Fi channel yesterday, and the theme was that the population of the earth 200,000 years from now was the center of the universe and that the population was hundreds of billions.

    But, from what I understand the population of the world is expected to get to 8 billion, and then to start to decline.

    I wonder if that is a filter of sorts?

  80. For some reason I can’t read “The Great Filter” without hearing the words spoken melodramatically by a hoarse Ian McKellen.

  81. Its wishful thinking to believe that the universe is teeming with life, much less intelligent life, and further, intelligent life capable of interstellar travel.

    The probability of any life developing from random particle interactions in this universe, given its assumed age, is so small as to be nil. The odds of abiogenesis occurring, together with speciazation, and then intelligence developing, are so low that you have a better chance of winning the lottery…every time you play it.

    Its a miracle for intelligent life to have developed on earth within 20 billion years. And yet people want to think that because “the universe is so big” and “the universe is so old” that, as if approaching infinity, every possibility must have occurred.

    Nothing more than wishful thinking by sci-fi geeks…

  82. strangelets

    I thought strangelets were very small weirdos.

  83. Poor, pitiful humans! The reason you haven’t detected us yet is that we have not yet seen fit to disclose ourselves to you. But once you cease to amuse us, we’ll disclose ourselves, all right – when we conquer your wretched little planet and harvest your organs to make snacks for our interstellar vending machines!

  84. Funny, but after reading the well-considered thoughts above, as well as many brilliant scientists’ opinions on this topic, I can’y help but think that Sinistar comes closest to the truth in his 3:28 p.m. post.

  85. Civilizations are by their nature robust. And with the multitude and variety of civilizations that could arise in billions of worlds and billions of years, the same small set of later stage filters could not destroy them all.

    That assumes the filter isn’t external

  86. Maybe intelligent races always back down from confrontations with Islamofascist races who hate them for their freedom.

  87. Pro L,

    Sinistar was lying, he is not sinistar, he is Urkobold.

  88. “Its a miracle for intelligent life to have developed on earth within 20 billion years. And yet people want to think that because “the universe is so big” and “the universe is so old” that, as if approaching infinity, every possibility must have occurred.”

    How do you know it’s a miracle? And why should I listen to people who insert the word “miracle” into their arguments?

    The problem with Libertarians is that they tend to lack imagination. It seems to stem from the 10 to 1 “crank” ratio that is present on here.

    I guess it’s part and parcel for a community that seems to be populated mostly by Computer Programmers, and Lawyers. You know, why even care or think about the possibilities when they seem so remote?

    What we should remember is that, as much as many of you would like to project a sense of having figured it all out because of your knowledge of SQL, your understanding of the Universe, and what is actually occurring, is fairly shallow in the grand scheme of things.

  89. Libertarians are lawyers?

    I thought lawyers were generally Democrats, believers in the government and all.

    And that libertarians were small business owners and such.

  90. 2 ideas-

    1) the “prime directive”. Maybe advanced civilizations purposefully hide from less advanced civilizations.

    2) there is a God and we are unique.

  91. Ron,

    If intelligence is extremely hard to evolve that would explain why we have encoutered no ETs nor overheard them chattering among the stars.

    Dunno if anyone else has mentioned this, but the answer to is probably simpler than that; namely, the reason we don’t hear anyone is because we can’t differentiate any noise they might be making from the background noise of the Big Bang. That’s why our radio and TV signals basically die out somewhere at the edge of our galaxy.

  92. I’m surprised no one has linked to the Exit Mundi website yet, which has numerous examples of possible “filters”:

    http://www.exitmundi.nl/exitmundi.htm

  93. I’ve always wondered why in the blue hell these otherwise fairly intelligent people are bound and determined to contact with a superior civilization? They even scrawled a map on our deep space probes so that anyone who finds it could find earth. They also included things like a map of DNA and other information.

    If earth like planets are rare, why encourage a superior civilization to come find it? When has a superior culture happened on an inferior one with resources and the inferior culture not either been enslaved, destroyed or trampled under foot? Why do they always see ET as some benevolent big brother who wishes to help poor little dumb earthlings become more advanced? It is more likely that ET would decide he wanted the planet for himself and either destroy the current inhabitants or use them as just another resource. Seems the smart move would be to listen, lay low and not try to communicate.

    That said I doubt there is any intelligent life anywhere else. I also doubt that f there were it would be possible to ever communicate or interact with them. The distances and obstacles are too great. I wish it weren’t so but the universe isn’t like star wars and star trek.

  94. Ron,

    I mean, the edge of our solar system.

  95. Perhaps a civilization evolved to godhood acts as the great filter. They’re just waiting to see what our singularity produces to decides whether to welcome the result or to exterminate it.

  96. “How do you know it’s a miracle? And why should I listen to people who insert the word “miracle” into their arguments?”

    I use the word ‘miracle’ in the sense of ‘beyond all reasonable probability.’ I would use the word to describe flopping a straight flush in every hand of hold ’em that I play and similar events in which probability approaches zero.

    But feel free to not listen to someone because they use a word you find, um, offensive?

    My point was that given the believed age of the universe (13-20 billion years depending on who you are talking to), the believed number of sub atomic particles in the universe, and the number of possible interactions between the particles that could have ever occurred in that amount of time, the likelihood of life of any kind occurring approaches zero. The likelihood of intelligent life occurring even once is of course many magnitudes more unlikely.

    To believe that there is intelligent life out there with the means of interstellar travel, simply because the universe is sooo big and sooo old, demonstrates a lack of understanding of modern cosmological theory. But by all means, disregard relativity and Big Bang theory in order to believe in all that Gene Roddenberry bullshit…

  97. If I were an intelligent extra terrestrial, I wouldn’t want to have anything to do with us either. Perhaps the fact that no ETs have visited us proves their intellectual superiority.

    Or perhaps the amount of time it takes to travel through space, even near light speed, is a barrier for any species, no matter how intelligent.

  98. My point was that given the believed age of the universe (13-20 billion years depending on who you are talking to), the believed number of sub atomic particles in the universe, and the number of possible interactions between the particles that could have ever occurred in that amount of time, the likelihood of life of any kind occurring approaches zero.

    I don’t understand you here. Usually arguments that pile large numbers upon large numbers don’t end with the words “approaches zero” unless those numbers are in the denominator. In this case, they aren’t.

    Incidentally, people with an “understanding of modern cosmological theory” believe the universe to be 13.7 billion years old.

  99. Just to point out, Nick Bostrom runs anthropic-principle.com. He is making a Anthropic argument based on his Strong Self-Sampling Assumption why evidence of sustained life-forms on Mars implies near human extinction.

    Copernican arguments and invoking Drake’s equation as a counter-argument are unconvincing if you ascribe to Anthropic bias in theoretical physics, which quite a bit of theoretical physicists, albeit grudgingly, now do.

  100. SugarFree,

    In other words… we’re hicks with no cell service. Great. I live in Kentucky on Earth and Kentucky in the Milky Way.

    On second thought, it sounds more like you are equating Kentucky to the Bo?tes Void. I was talking of Earth being more like out in the suburbs beyond commuter train service.

  101. Ron,

    OT: Is there anything new on that “dark matter” theory, or is it just a mathmatical place holder to make the models work until something real is discovered to fill in there?

  102. While it can be entertaining to speculate on alien existence or lack thereof, it has little benefit other than providing a foundation for logical rhetoric. Given all knowledge our species has collected since beginning the endeavor, we have absolutely none pertaining to extraterrestrial life. Hence, any assumptions made are based entirely on a relative population size of one. Conclusions reached with that singular sample are highly improbable at best and certainly anthropocentric in origin.

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