Why Silence Puzzles

Bryan Caplan:

[Recent planet] discoveries seriously undermine the Fermi Paradox. If we’ve only recently confirmed the existence of extrasolar planets, why on earth should we be surprised by the fact that we’ve failed to confirm the existence of extrasolar intelligent life? … Shouldn’t they already be here? Not if space travel (including the value of time) permanently remains extremely costly relative to the value of raw materials. It’s a lot easier to believe that space travel will forever remain a rare luxury for intelligent life than that intelligent life exists on Earth alone. ..

[Some] say, “Whatever intelligent life usually does, surely one species of intelligent life would be the exception that proves the rule.” Facile. When you multiply independent, rare events together, you quickly reach situations with zero examples. … Even if there are seven billion species of intelligent life in the galaxy, there could easily be zero species that entered our solar system during the last century, approached the earth, and stayed long enough for the scientific community to detect and confirm.

When a tree burns, what fraction of its leaves float to another tree still burning enough to ignite it? What fraction of the coconuts on an island float away to a barren island to grow a new tree there? What fraction of the virus copies in someone who is infected fly out in a sneeze to infect a new person? Why should we ever expect such fractions to be large enough to create forest fires, or coconuts on new islands, or viruses that spread to many people?

If we knew that one tree in our dense dry forrest was burned a few days ago, we should be surprised to see untouched trees near where we stand, even if we could not see that burned tree far away. We should also be surprised to see unburned coal near us if we knew a fire had started days ago far away, beyond our sight, in the same rich ventilated coal mine. And if we knew that one drop of spoiled milk was added days ago to a large room temperature vat of milk, we should be surprised to see unspoiled milk in any part of the vat we could see.

We should be surprised to think billions of technologically-advanced intelligent civilizations have existed in our galaxy for billions of years. This is because for a civ only a millennia more advanced than us, it should only take a tiny (i.e., a part in a billion or less) fraction of its resources to send out a self-reproducing seed that could colonize an empty galaxy densely (so that we’d see it everywhere we looked) within a billion years. It doesn’t matter if this venture is expensive and time-consuming relative to the typical hobby budget or time of a human today, or a bacterium on any day. What matters is that civs can be diverse, and contain great internal diversity. And it just takes one spark to start a fire.

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  • Jim Rutt

    There was a good recent book laying out 50 different ways “why there might be no aliens”:

    If the Universe Is Teeming with Aliens … WHERE IS EVERYBODY?: Fifty Solutions to the Fermi Paradox and the Problem of Extraterrestrial Life
    by
    Stephen Webb

    http://www.amazon.com/Universe-Teeming-Aliens-WHERE-EVERYBODY/dp/1441930299

    Only ONE needs to be true for there to be no advanced civs. Or indeed only one to be very hard for advanced civs to be extremely rare (on the order of 1 per galaxy).

    Some examples of pruning rules [my own glosses] :

    1. “differentiated multicellularity (ala the Cambrian explosion might be very low probability”.

    2. “all advanced civs quickly get eaten by an AI Singularity” – that one of course begs the question: “why wouldn’t at least one of those AI Singularities embark on galactic colonization?”

    3. “all advanced civs agree to observe a star trek like ‘no meddling rule’” – though of course that rule was honored in the breach every other episode!

  • Robert Koslover

    As has been noted various times previously at this blog: (1) communication over vast distances is enormously easier than transportation, but (2) even mere communication itself is exceptionally difficult, due to poor signal to noise ratios when using anything other than enormously powerful signal sources, once again due to the vast interstellar distances. (It is not true that our TV and radio broadcasts are readily detected at interstellar distances from Earth.) Now, personally, I suspect that a sufficiently advanced civilization might choose to announce its presence by harnessing the power of a star. After all, stars are among the very few energy sources that are able to generate signals easily detectable over vast interstellar distances. So… keep your eye (and telescope) out for any stars whose intensities are modulated (possibly at high rates) in a manner that carries information. Such a finding could be the surest sign of an advanced intelligence at work. Just my humble opinion.

  • http://jacobageller.com Jacob AG

    Consider the vastness of the universe, and what that means for the probability of there being billions of intelligent life forms somewhere out there, if not now then at least at some point in the past.

    There are currently about 170,000,000,000 galaxies in the universe (that we know of), each with something like 100,000,000,000 stars in it, on average, in a universe that’s about 13,000,000,000 years old.

    So if any given star (other than ours, of course) in our 13,000,000,000 year-old universe, has better than 1 in 170,000,000,000,000,000,000,000 odds that a planet around it has had intelligent life on it, then we probably haven’t been the only intelligent life forms in our universe’s history, and we might not even be the only ones right now.

    In other words, if the probably of any given star has just one planet with intelligent life on it at some point is just 0.00000000017% — an almost incomprehensibly low probability — then approximately one hundred billion planets have had intelligent life on them at one point or another, and given the relatively low age of the universe (13 billion years) there could be tens, hundreds, or even thousands of civilizations in the galaxies of which we are already aware.

    It would therefore seem that the average star in our universe must be *extremely* — almost incomprehensibly — inhospitable to intelligent life for us to be the only intelligent life forms in the universe. And it seems all the less likely that we’re alone because we know of at least one planet with intelligent life — ours — so the probability of any star having intelligent life swirling around it, no matter how low it might be, must be greater than zero.

    • Captain Oblivious

      You seem to be re-inventing the drake equation:

      http://www.activemind.com/Mysterious/Topics/seti/drake_equation.html

      Frank Drake breaks it down into a few more factors; the only particularly interesting one being the “lifetime” of a civilization – if a civ lasts for, say, 13,000 years before somehow imploding, then 999,999 of every 1,000,000 civs have already imploded and are unavailable to us.

      Of course that factor, like much of the discussion, presupposes a linear rate of civ formation over the last 13 billion years. But that’s not realistic: the early universe had very few heavy elements, which are necessary for life and civ (as we know them, anyway); given that stars must first forge heavy elements out of lighter elements, the first 2/3 or so of the universe’s existence would not have been particularly hospitable.

      • Captain Oblivious

        Oh, and what sort of results do other people get out of the Drake equation? I’ve always understood that if you put plausible numbers in, you get implausibly large numbers out (e.g. thousands or even millions of civs right now in our own galaxy)

        But every time I try it, I get back numbers right around 1.0 (+/- a factor of 10). Am I a pessimist? A cynic? A realist? Or what?

      • Tony

        To captain obvious: I consistently get numbers ~ 100 per galaxy sized like our own (this puts the average distance to one at about 8,800 light years) with very low rates of formation that are probably on par with yours but much longer average lifetimes than most people seem to give. I have a background in biology and a bit of astronomy, and my estimations of the probability of creatures arising with general intelligence is somewhat low. But I don’t consider the implosion/exponential expansion through the universe dichotomy to be a valid one. I’m fairly convinced the universe as a whole is pretty hostile to self-replicating systems, and that we are living in an extremely atypical era of human history full of exponentiation that warps our expectations of the future. I see little reason that our progeny couldn’t be living on Earth 5 million years from now, not having ever left our solar system with anything self-replicating.

  • Tony

    These analogies presuppose that the universe is fundamentally hospitable to self-replicating complicated systems, ‘waiting’ to be converted by them. A metastable state, like a dry forest in an oxygen atmosphere that can chain-react in a fire. What this says to me is that there is a high probability that the universe is fundamentally hostile to complicated self-replicating systems in general, with only small pockets (like the surface of the Earth) where it can really take off.

  • http://timtyler.org/ Tim Tyler

    That is not one of Bryan Caplan’s better articles :-( Hanson is correct, Caplan is incorrect.

  • richard silliker

    Why is a potentially misleading question. The question why is an attempt to assign blame.

    Perhaps “they” are already here but fail to recognize us because of our behaviour.

    It is all about the behaviour of mass.

  • Abelard Lindsey

    The emergence of the Eukaryote was a singular, rare event and was necessary for the emergence of complex (multi-celullar) life.

    http://journalofcosmology.com/Abiogenesis107.html

    It certainly explains the Fermi paradox.

    • http://daedalus2u.blogspot.com/ daedalus2u

      That is very likely not correct. Eukaryote-like events have happened multiple times.

      The symbiosis of the mitochondrion did occur from a singular event, but there may have been other instances of mitochondrion-like symbiosis which have all been out-competed by the descendants of the singular mitochondrion. If the singular mitochondrion event hadn’t happened, one of the other mitochondrion-like events would have and there might not have been much delay.

      The symbiosis of the chloroplast was another eukaryote-like event.

      Such events are still going on now.

      http://www.newscientist.com/article/dn21353-zoologger-unique-life-form-is-half-plant-half-animal.html

      Oxygenic carbon fixing photosynthesis would have evolved because of the shortage of carbon. If there were no mitochondrion containing lifeforms, there would be an enormous niche that could be filled by a mitochondrion-like organism. That niche remains open until a mitochondrion-like organism evolves.

  • http://jcwitmer.blogspot.com Jake Witmer

    We don’t know who’s correct, unless we’ve witnessed aliens.

    I really like what Bryan Caplan writes, and I really like what Robin Hanson writes. Both have reasonable assumptions that succeed or fail on the presentation of new, currently unavailable, evidence.

  • Vlad

    This seems to me to lead to several possibilities:

    1. The emergence of technological species is really very unlikely, so we’re alone in the galaxy.

    2. Aliens are already here, we’re just not aware of it (they’re just observing or even interfering, who knows?).

    3. For some reason every single civilization ends up destroying itself (or destroying each other).

    4. For some reason technological development is asymptotic towards some fixed level which is insufficient to allow for inter-stellar travel or communication.

    Am I missing some possibility here?

    I would attach about 40% probability to each of the first two possibilities, and 10% to the last two. It seems to me that all those possibilities are philosophically troubling, each for a different reason.

    • http://daedalus2u.blogspot.com/ daedalus2u

      I think that #3 is 99.9999% likely. There are some particular idiosyncrasies of human evolution which might help us avoid it, but probably not.

      It is not so much that the universe is inhospitable, just that organisms that evolve sufficient intelligence to use tools are unable to also evolve sufficient wisdom to not destroy themselves. Humans are certainly not at that point yet. We could be, but because triggering tribalism, xenophobia, hatred and bigotry is still an effective tool to manipulate other humans and gain disproportionate power and resources, humans continue to do it, and those who are most effective at obtaining it are also the least able to not use that power to destroy those who are not effective at attaining it.

      All organisms are going to have the equivalent of an “uncanny valley”, to enforce speciation and to prevent formation of non-fertile hybrids. This ensures that all organisms are going to be able to have tribal affiliations sufficient to allow them to kill non-tribe members. Because tribal affiliation can’t be transmitted genetically (there isn’t sufficient information in the genome to encode tribe pattern recognition, tribal affiliation has to be learned once the brain forms), tribal affiliation is malleable and those most effective at manipulating it will use that power to destroy their opponents.

      Once large scale genocide starts to happen, there will be no stopping it. The survivors who are most brutal will form the next generations and the next series of genocides will be more brutal still. They will keep getting more brutal until the organism goes extinct.

      Robin’s unspeakable arrogance is a manifestation of that tribalism induced xenophobia. The whole GOP presidential candidate field exhibits it to an even higher degree. All of them are willing to bomb Iran, even though there is not a chance that bombing Iran would stop Iran from acquiring nuclear weapons, unless the bombing is genocidal. If it is ok for the US to genocidally bomb Iran, then at some point someone will do the same to the US, and if the US is the last nation left on Earth, then the red states will bomb the blue states.

      Why does the Bible say “the meek shall inherit the Earth”? Because if they don’t, there won’t be an Earth left to inherit, or any people to do the inheriting.

      • Konkvistador

        Humans seem to have self-domesticated themselves over the past few thousand years. We’ve become much more docile as individuals, whether that be genetic or environmental (at least if Steven Pinker-like arguments on this are true and we aren’t cherry picking data).

        Any brutal genocidal tribe will have free-loaders who aren’t too keen on brutal genocide, maybe just because it personally costs them resources. Let other tribe members do the genocide for you and you can just claim the rewards.You don’t have to personally kill off the Germans or the Poles or Native Americans to inherit their land and resources.

        Group selection is weaker than individual selection.

      • ShardPhoenix

        There have been plenty of genocides throughout history, but we haven’t seen the kind of inescapable downward spiral you suppose. I do think there’s a pretty high chance that most/all civilizations destroy themselves though, because the amount of destructive power that one or a small number of people can wield seems to go up over time.

      • http://daedalus2u.blogspot.com/ daedalus2u

        “Group selection is weaker than individual selection.”

        Yes, exactly. Unless humans configure their societies to irreversibly and unconditionally favor group selection, then as technological progress increases capabilities, individuals who utilize those increased capabilities for their own advantage will destroy their own, and every other group.

        Favoring any group smaller than the entire human race will lead to extinction.

      • http://daedalus2u.blogspot.com/ daedalus2u

        Konkvistador, It doesn’t need to be the average human who is a raving genocidal maniac, all it takes is one leader, a few followers and a lot of people not objecting because at first they don’t come for them.

        Eventually they do come for everyone.

        Once technology achieves virtual immortality, the “leader” has to and does kill all potential rivals. The “leader” can’t be deposed other than by death because the “leader” controls enough power to kill all potential rivals. The “leader” cannot allow any development of any power or technology that he/she/it does not control.

        Any economic system that allows for private control of wealth will eventually lead to only one “leader” at the top as that wealth is used to acquire more power and more wealth. That wealth will then be used to stifle the acquisition of wealth and power by all others.

      • Captain Oblivious

        Any economic system that allows for private control of wealth will eventually lead to only one “leader” at the top as that wealth is used to acquire more power and more wealth. That wealth will then be used to stifle the acquisition of wealth and power by all others.

        I see… unlike systems without private control of wealth (e.g. USSR, DPRK, etc), in which no one ever acquires enough wealth/power to stifle others.

        HELLO?!?!?!?!?

      • http://daedalus2u.blogspot.com/ daedalus2u

        Captain O, what is this USSR that you speak of? As far as I know, it no longer exists.

        Now there is private control of wealth in the former USSR. Is that turning out better?

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

      • Captain Oblivious

        You’re right – the USSR no longer exists. It imploded, because large-scale “collective” ownership of wealth is, in practice, totally unworkable. ONLY private ownership of wealth (and more specifically, voluntary transactions thereof) provides the freedom that we deserve and the improvements in productivity that we need to advance.

        I mean seriously – aside from some early successes in the space race, what technological advancements has a “collective ownership of wealth”-type society produced? Look at the track record over the past 100 years of collectivist vs capitalist economies!

        And yes, people can be self-centered, uncaring, and downright cruel. But that’s people for you, and they’re an unavoidable component of any society – so man’s sometimes-overly-ambitious nature is not an honest argument against capitalism, just a lame attempt at rationalizing something you already believe in.

      • http://daedalus2u.blogspot.com/ daedalus2u

        The USSR didn’t have collective ownership, everything was “owned” by the Communist party and controlled by the senior officials for their own power.

        The problem is power concentration. Doesn’t matter if that power is private or public. If that power can be exercised so as to gain more power, then the system is unstable.

        Power corrupts and absolute power corrupts absolutely.

        Productivity in the US was greatest in the 1960′s.

      • Oliver

        Human bodies relative to ants are very powerful, and of course they are capable of self-destruction, but they are also capable of crossing entire seas where ants cannot. If enough humans worked as a body it could cross the ocean of space — the individual cells merely need to cooperate and have sufficient high-level mechanisms for destroying cancers that arise in its lifetime, if the analogy be that a body needs to survive especially long to cross this ocean. If evolution has found a competitive niche to create billions of massive clunky humans despite the advantages of comparatively decentralised single-cellular life then I think society can think of reasons to centralise humans into cooperative societies that can even have mechanisms to extinguish existential disaster.

        (My thoughts are not at all set.)

  • Vaniver

    Isn’t Caplan just saying “there is no forest, the trees are miles apart,” whereas you’re saying “there is a forest, the trees are touching”? That sounds like a technical question that’s difficult to confidently answer (though it seems to me that the trees are more likely to be miles apart).

    • Alexander Kruel

      Agree with Vaniver. The whole argument rests on assumptions about technological advances. I don’t see why the inference has to be that there either are no aliens or that there is a great filter. What if ideas about how capable advanced technology can become are fundamentally flawed? Without advanced AI and nanotechnology it might be almost unfeasible to travel the stars. And without advanced nanotechnology there won’t be any EM’s either.

      (Of course, Robin Hanson has thought about all this a lot while I barely scratched the surface.)

      • http://timtyler.org/ Tim Tyler

        If ideas about how advanced technology can become are flawed to the extent that not even interstallar travel turns out to be practical, then surely much that we think that we know is wrong.

      • Alexander Kruel

        Tim, interstellar travel might be practical if you can cryo suspend people or use emulations. But that won’t happen without certain amounts of advanced nanotechnology and computational resources. And even if we are talking about generation ships of living humans, you’d need advanced machine maintenance and manufacturing equipment. I don’t think that it is just obvious that those technologies will become a reality.

        Much of what some people believe to know is based on extrapolations of current trends mixed with pure speculation.

        Self-replicating spacecrafts sound really cool and convincing when formulated in English. But to derive all mathematical truths from a well-defined set of axioms and inference rules in symbolic logic did also sound possible at some point. Even antimatter weapons sound superficially possible. And indeed they are, but not economically realizable.

      • http://timtyler.org/ Tim Tyler

        Interstellar travel doesn’t depend on cryonics, brain emulations, or sending ships of humans. We will just send machines.

      • SpaceEatingMonster

        Interstellar travel doesn’t depend on cryonics, brain emulations, or sending ships of humans. We will just send machines.

        What for?

  • Alexander Kruel

    If you do not assume that we will be able to reach other star systems with washing machines then all you did was replacing humans or emulations with AI. You will still need advanced nanotechnology for maintenance and manufacturing. And in conjunction you will have to come up with adequate AI, which is yet another technological prediction that can fail to deliver the desired results.

    I repeat, it is easy to say “just send machines” but that doesn’t prove much.

    Admittedly, a civilization that is many millions of years old will at some point brute-force AI. But at that point they will have already improved themselves. And after being trapped in their own star system for millions of years, if they survived, it is questionable if there will be many that care to travel to other stars. It is also questionable if the social and economic circumstances will allow them to do that anyway.

    You have to apply incredible amounts of technological optimism to say “we will just send machines”.

  • Billy Brown

    As usual when discussing the Fermi Paradox, I see lots of comments that don’t take into accound the scale of the issue. Specifically:

    1) It doens’t matter if interstelar travel takes a century, a millenium, or a hundred thousand years to become feasible. It amounts to the same thing on an astronomical time scale of 10^8 – 10^9 years.So technological difficulty only matters if you posit that interstellar travel is physically impossible, not just hard.

    2) It doesn’t matter if 99% of all civilizations blow themselves up before spreading to multiple star systems. The first one that doesn’t can colonize the entire galaxy in a few million years, which is still very fast on an astronomical time scale. So extinction is only a viable explanation if you posit that it’s essentially a natural law that any possible civilization is 100% likely to utterly exterminate itself before it begins to spread.

    3) It doesn’t matter if 99% of civilizations don’t care about expansion. Like case 2, the one exception that does care will colonize the galaxy very rapidly.

    4) Explanations based on social mores are implausible, because they assume a civilization spanning billions of star systems is going to stick to the same (rigidly enforced) rules for tens of millions of years.

    5) The fact that space is big makes little difference, because expansion-oriented civilizations display exponential growth. Even with slow STL travel it would take only a few million years for an expanding civilization to colonize every system in the galaxy.

    Really, there are only a few types of explanation that work. Either advanced civilizations are so incredibly rare that there isn’t another one in our past light cone, or they’ve only become possible in a recent round of galactic star formation and haven’t had time to spread yet, or we live in a simulation. Or, alternatively, there’s a filter in our future that no civilization ever succeeds in passing through, so there’s not much point in worrying about it.

    • http://timtyler.org/ Tim Tyler

      Surely not our whole “past light cone”! It is only intra-galactic travel that looks managable. Inter-galactic travel might well happen only when galaxies collide – which is not *that* often.

      • Billy Brown

        Strictly speaking it would be more like our past V=0.1C cone, plus or minus a bit depending on what you think the plausible upper limit for STL colonization attempts would be.

        But whle intergalactic space is much lower-density than a galaxy, it isn’t actually an impermeable wasteland. Between halo stars, dwarf galaxies, stray globular clusters and individual orphan stars it’s probably quite feasible to cross the local group in jumps of 10^9 systems would get around to in a few million years.

      • Billy Brown

        Oh, for an edit feature!

        That should have been “in jumps of less than 1,000 LY. Since there’s no law of physics that forbids such journeys I wouldn’t rule them out, especially since we’re talking about things a galactic civilization of billions of systems would get around to in a few million years.”

      • Captain Oblivious

        The spacing between galaxies (within a cluster, anyway) is only about 10x the diameter of a large galaxy…. the spacing of star systems is about 100,000x the diameter of the hospitable portion of our solar system… so inter-galactic travel would be much easier for an intra-galactic civ than intra-galactic travel would be for an inter-planetary civ.

    • http://daedalus2u.blogspot.com/ daedalus2u

      Billy, a civilization doesn’t get beyond its own first planet unless it has a social system that can tolerate it. Right now, humans don’t have one that can tolerate it.

      What would the US do if China put a manned base on the moon? Would the US cooperate with the Chinese? Or would the US destroy it? How powerful would the US allow the Chinese moon base to get? What if Iran put a manned base on the moon?

      Right now humans can’t agree on what to do about AGW. In the US they can’t agree on fixing what is broken (roads and bridges) when there is manpower to fix it (super high unemployment in construction) when borrowing money is cheaper than it has been in generations.

  • http://timtyler.org/ Tim Tyler

    Civilization seems destined for extinction or a “big” future – with intelligent machines and nanotech – to me. IMO, we won’t dally around in the current spot for very long.

    A lack of expansionism is just about imaginable – but Caplan has seven billion species of intelligent life with *none* of them being expansionist – which is *much* harder to imagine.

  • Jim Rutt

    Here’s a link to some progress on understanding the evolution of differentiated multicellularity:

    http://www.physorg.com/news/2012-01-scientists-replicate-key-evolutionary-life.html

  • mjgeddes

    If the observable physical universe was just a narrow part of a much bigger reality that we are currently unaware of, and this ‘bigger reality’ was far superior (in terms of resources, economics, etc) , then all the advanced civs will have migrated to this other place.

    Think ‘The Hall of Worlds’. I suspect the ‘physical universe’ that we know about comprises ‘narrow corridors’ in a much broader platonic ‘hall’ of pure math forms. In theory we should be able to enter the hall of worlds from any point in space and time. The creation of FAI will give us the ‘access key’ , ‘turning the locks’ of ordinary space-time to open a portal to this dazzling wider reality. It is likely we will then all pass out of the observable universe, and join all the other ‘powers’ of the universe in the hall.

    Just one additional assumption explains the Fermi Paradox. Once you enter the hall, you cannot return to the ordinary physical universe (or at least, there are severe restrictions on your exit points).

  • koto

    When I hear people discussing the possibility of alien civilizations, and wondering why we have not caught sight of them yet, I cannot help but think of the Combine from Half Life 2. To me the Combine is the most likely variety of interstellar civilization we would encounter – a monstrous, all-consuming swarm, an unrecognisable blend of technology and biological, sweeping across the universe enslaving and devouring all in their path. It seems to most likely that if an intelligent species were to leave their homeworld en masse, it would most likely be one that had already nigh-killed its own home, and such an effort would be led by members who had the least qualms about consuming other worlds. The difficulties of transporting species adapted for planetary ecosystems leads me also to believe that such an interstellar species would be one that had abandoned all of its values of caring, nurturing, natural existence, a species that, driven by insanity and hatred, would extirpate basic values of respect and dignity, turning their bodies and minds into fuel for experimentation.

    I could see humans fulfilling this ideal.

    However, the much easier answer is that interstellar travel is so prohibitively slow and expensive that it will never be accomplished by any species. We should be thankful. Look at what a disgusting mess we have made of our planet. Look at how Europeans have destroyed the beautiful, ecologically-attuned indigenous societies of the Americas, Africa, and Australasia. Why should we want to let our greed and inhumanity spread out from this planet? Why should we wish the fate of our own world on any other?

    • koto

      On reflection, we should stop worrying about extraterrestrial life. We should realise that extraterrestrial contact has already occurred on this planet: the re-connection of Western, European peoples, and the indigenous peoples of the “New World” was such a meeting. And we can see how well that went: cultures that had slowly built up, over thousands of years, to live in delicate, balanced relationships with their natural environments, were disintegrated in the blink of an eye by a ravenous, overwhelming horde of alien invaders. We came off our ships and proclaimed sovereignty and declared the customs of those we encountered savage. Then we set about breaking open and harvesting their lands. We are almost at the threshold of the butchering of the earth’s natural resources (or at least I shudder to think how much further this process might go). Now we live in a dying, consumed world, spinning fantasies about how “advanced” we might be in a million years time. But the truth is that none of our “advances” have challenged the basic realities of physics and ecology. Our advances have instead led us to the precipice of cultural and ecological self-destruction.

      It is clear, then, that the realities of interstellar travel is that is impossible. So, all contact between alien cultures must remain terrestrial. And this has already happened, largely over the course of the last five hundred years. Yes. We have already met aliens: they are us.

      • Jeff Schnitzer

        Your eden-like description of “time before the white man came” feels about as realistic as a Disney cartoon. Most indigenous peoples of the new world lived in precarious imbalance with giant civilizations rising and collapsing as they overextended their natural resources, engaged in wars with neighbor civilizations, suffered new diseases, and endured all sorts of tragedy that archeologists speculate on to this day. Even the Aztecs marveled at the ruins of the Teotihuacanos and wondered what could have destroyed an empire and civilization vastly greater than what they achieved.

        I strongly recommend reading Chinua Achebe’s _Things Fall Apart_ for a much more nuanced and realistic view of the clash between alien cultures. One conclusion I think is safe to draw from this book: However nasty modern human culture may be, it’s still a significant improvement from even 100 years ago.

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  • The Bard

    Only one explanation rings true. They are already watching us. We’re in a kind of ‘hands off’ Procterate, along the lines of the Kenyan Preserve — a huge planet sized Game Preserve. Which means goodness and love won, and God really is the aliens. And yes, they probably have far more interesting places to be than this single universe. So enjoy life — we all in live in a Game Preserve!

  • JC

    There is no value to be gained in the present by seeding the galaxy. It is evolutionarily pointless.

    There is no reason not to believe that the Fermi Paradox may arise from the simple fact that evolution for intelligent species may favor comfort.

    Consider that we’re only a half century past Jack Kennedy’s “we do these things not because they are easy” speech. And today a vast portion of our industrial output goes into LOLcat transceivers and dildos instead of trying to build sub-light speed space vessels.

    Comfort may simply trump adventure.

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  • Nick

    Nearly all discussions of this issue profoundly underestimating the amount of information astronomers actually have about the universe. We have spectroscopic data on not only billions of stars in our own galaxy (along with associated dust clouds and the like), but also on billions of other galaxies. They all look perfectly natural. Galaxies where most of the surfaces and illumination have been efficiently engineered would stick out in the spectra like sore thumbs.

    Since out of billions of galaxies we’ve found none converted to artificial surfaces or illumination methods, something we should expect a significant fraction of ETI to have done over the many billions of available years, it’s astronomically unlikely that we share our own galaxy with any other ETI.

    Either that or all over the universe the aliens are all very good at hiding, like elves and dwarves.

  • http://www.frejwasastjerna.net The Monster from Polaris

    My favorite explanation of the Fermi paradox has long been the strong suspicion that abiogenesis is extremely unlikely. Sure, amino acids and the like form readily under the conditions assumed to prevail on the early Earth, but the road from that to self-replicating systems is very long and may be very unlikely.

    Sir Fred Hoyle famously likened abiogenesis to a tornado stirring up a junkyard and assembling it into a jumbo jet, and I consider this a good, though slightly exaggerated, analogy.

    It’s true that Hoyle’s analogy ignores 3 factors making abiogenesis somewhat less unlikely:

    1) Unlike a random junkyard, organic molecules at least have the ability to join up into the required combinations.

    2) In terms of the analogy, it isn’t necessary to get a Boeing 747 directly; something like the Wright Flyer will do. Once you have a self-replicating system, natural selection will refine it.

    3) Finally, we’re not contemplating a single tornado in a single junkyard over a short span of time but bazillions of tornadoes stirring up bazillions of junkyards over eons.

    Even so, I suspect the probability of abiogenesis on one planet may be more like 10^-100 than 1.

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  • http://www.copcutt.me.uk Robert Copcutt

    The sun is expanding and in a few billion years we will fry if we do not move. A huge asteroid could hit us any second and wipe all life off our Earth. For these reasons we have a responsibility to make every effort to colonize other planets as soon as we can.

    The possibility that requires the most careful consideration is the increasing danger of self annihilation. We are staring “The Filter” implied by the Fermi paradox so close in the face most people do not appear to be able to see it. Humanity must soon make the choice between becoming super-ethical or being wiped out. At http://www.copcutt.me.uk/SETI.htm I explain in more detail why this can be the only explanation, if we consider All the facts.