Do Alien Civilizations Inevitably ‘Go Green’?


In the famous words of Arthur C. Clarke, “Any sufficiently advanced technology is indistinguishable from magic.” This phrase is often quoted to express the idea that an alien civilization which may be thousands or millions of years older than us would have technology so far ahead of ours that to us it would appear to be “magic.”

Now, a variation of that thought has come from Canadian science fiction writer Karl Schroeder, who posits that “any sufficiently advanced technology is indistinguishable from nature.” The reasoning is that if a civilization manages to exist that long, it would inevitably “go green” to such an extent that it would no longer leave any detectable waste products behind. Its artificial signatures would blend in with those of the natural universe, making it much more difficult to detect them by simply searching for artificial constructs versus natural ones.

The idea has been proposed as an explanation for why we haven’t found them yet, based on the premise that such advanced societies would have visited and colonized our entire galaxy by now (known as the Fermi Paradox). The question becomes more interesting in light of the fact that astronomers now estimate that there are billions of other planets in our galaxy alone. If a civilization reaches such a “balance with nature” as a natural progression, it may mean that traditional methods of searching for them, like SETI, will ultimately fail. Of course, it is possible, perhaps even likely, that civilizations much older than us would have advanced far beyond radio technology anyway. SETI itself is based on the assumption that some of them may still be using that technology. Another branch of SETI is searching for light pulses such as intentional beacons as opposed to radio signals.

But even other alternate searches, such as SETT (Search for Extraterrestrial Technology), may not pan out either, if this new scenario is correct. SETT looks for things like the spectral signature of nuclear fission waste being dumped into a star, or leaking tritium from alien fusion powerplants.

Another solution to the Fermi Paradox states that advanced civilizations will ultimately destroy themselves. Before they do though, they could have already sent out robotic probes to many places in the galaxy. If those probes were technologically savvy enough to self-replicate, they could have spread themselves widely across the cosmos. If there were any in our solar system, we could conceivably find them. Yet this idea could also come back around to the new hypothesis – if these probes were advanced enough to be truly “green” and not leave any environmental traces, they might be a lot harder to find, blending in with natural objects in the solar system.

It’s an intriguing new take on an old question. It can also be taken as a lesson – if we can learn to survive our own technological advances long enough, we can ultimately become more of a green civilization ourselves, co-existing comfortably with the natural universe around us.

47 Replies to “Do Alien Civilizations Inevitably ‘Go Green’?”

  1. There’s no reason to suggest all other aliens are more advanced than us. Metal-rich population II stars are relatively brand new in the history of the universe and thus sophisticated life hasn’t had much time to develop. It’s more likely that we are the first intelligent species to emerge from the universe. The obvious challenge to that idea is to prove that metalicity is not actually correlated with sophistication of life or that the “Big Bang” model is false. However, a look at WebElements plotting all the elements in the periodic table that our bodies depend upon illustrates how improbable that is.

    1. ” It’s more likely that we are the first intelligent species to emerge from the universe.”
      The universe is anywhere from 14-46 billion light years in size… and at least 14 billion years old. Our home star Sol is 2nd or third generation in our local cluster, about 3-4 billion years old…
      You’re believing that we human hominids are the first intelligent beings in the universe…
      Whenever you’re ready…

    2. Kepler has found, AFAIK, that frequency of terrestrials are not affected by metallicity of stars, it is giants that become rarer with less metals.

      So likely the 2nd generation stars had habitable planets. Some of those M stars would survive to today with lifetimes ~ 100 Ga (billion years), and some habitable planets too with superEarth’s atmosphere lifetimes ~ 20 Ga.

      It took our biosphere ~ 2-2.5 Ga to oxygenate the atmosphere, which is a prerequisite for large complex life. Technological competent life took another 2 Ga, so it seems a rare, happenstance trait for biologists. But there are many stars, so we should expect the first such civilizations to appear ~ 2-3 Ga after Big Bang. (IIRC the 1st generation stars lasted ~ 0.1 Ga.)

      That means the oldest planets that had or have technologically competent life would be ~ 10 Ga old by now.

      1. The point about Kepler’s findings on metallicity and terrestrials is an important one indeed.

        One issue I see is that systems lacking gas giants would have rocky planets more vulnerable to asteroid impacts as evidenced by Jupiter’s role in our system.

        I suppose the question I would ask is how many systems with rocky planets lacking gas giants would not actually experience numerous asteroid impacts preventing life from thriving or even experiencing genesis? Or is our system the odd one out in this case?

  2. So little green men really means they are environmentally green?

    Sigh… yet another anthropocentric idea being applied to extra terrestrial life being taking seriously?? Come on please!

    Any advanced alien ‘civilizations’ are not going to be anything like ours at all. Why would you even think this to be the case? Too much Star Trek?

    They more than likely will think in ways we could not currently comprehend given they evolved in a completely alien environment, have a completely different biology, and a completely different history. They simply would not have similar values that we share.

    Believing that aliens are ‘environmentally friendly’ is inline with believing that they have two eyes, two arms, two legs, and answers to the name of ‘Spock’ or ‘Dejah Thoris’.

    It doesn’t bother me that a SciFi writer came up with this. SciFi is fun to to think and fantasize about. But please… no one could take this idea seriously (I hope).

    1. It’s not entirely unlikely that some alien life will have things in common with us. It’s all speculation at this point as you point out.

    2. “Believing that aliens are ‘environmentally friendly’ is inline with believing that they have two eyes, two arms, two legs, and answers to the name of ‘Spock’ or ‘Dejah Thoris’. ”

      That is a preposterous comparison to make. Are you seriously suggesting that the chances of aliens possessing an identical morphological makeup to us (for which there is no evolutionary reason why this should be) is similar to the far more general requirement of not F-ing up the biosphere in which they evolved as their technology advances (a condition for which there is a HUGE evolutionary pressure to adhere to)?

      1. Yes that is exactly what I am suggesting. Going ‘green’ is a very human idea. You can’t possibly believe the reason we haven’t detected other life forms is because they are so ‘green’ that we cannot distinguish them from natural phenomena as the sci fi author suggests.

        There are more obvious and logical reasons why we have not detected them such as they are too far away and they do not communicate as we do.

        Not only are the ideas here heavily based on human biases, they are based on our current level of technology and on our current predicaments.

        It’s like stepping out of the stargate and everyone speaking English. It makes the story move along faster but it’s just plain silly to think it is possible let alone probable as the author suggests..

      2. “Going ‘green’ is a very human idea.”

        What does that even mean? Of course it’s a human idea. Cats didn’t figure it out. We worked it out because we’ve discerned a very real and very fundamental problem – if your pace of technological development increases to the point where you are damaging the place in which you live, altering the conditions that allow you to survive in that place, then you have a problem. The solution to that problem is to not balls up your homeworld, and to do that, by definition, you can’t be pissing in your own bathtub. You need to live in a way that minimizes the impact you are having on your world, or at least cancels it out.

        There is a negligibly small chance of finding an alien that looks like us and speaks English. Finding that an alien recognizes the value of not destroying their own world and the very environment they require to live is, if not a foregone conclusion, at least significantly likely. There is no surprise in this and no reason to think otherwise unless evidence to the contrary emerges. The whole ‘aliens will be so unknowably different from us we couldn’t possibly know what they would do’ is philosophical masturbation. Presumably, aliens will live in the physical universe, and be subject to its laws, and be subject to very fundamental principles like doing what is conducive to ones own survival. Thus, we can assume that given the choice, the majority of aliens will try to act in ways that ensure the preservation of their world, or the environment on their spaceship, or wherever the hell they live. The ones that don’t will die out, which I suspect is a more significant part of the reason that we aren’t detecting them left right and centre. Now, of course I don’t believe that the reason we have detected aliens is because they are so advanced that they are communicating with cans joined by string and driving vehicles powered by juniper berries, but that isn’t what we’re talking about here.

      3. I’m sorry I didn’t mean to upset you. Perhaps I used a poor choice of words.

        This isn’t really worth getting so excited about.

      4. Ahem – you’re right. I’d been up for 36 hours straight when I wrote this, and must have been narky and at least a little foggy. In the light of the morning, it looks a little ridiculous and certainly not worth getting fired up about.


  3. Any form of intelligent life on a planet that develops technology will face the same problems we face now, to one degree or the other. Any technology requires the use of energy and the conversion of raw materials into other forms. This will lead to problems of resource exhaustion and the contamination of the planetary environment with byproducts and waste. The alternatives are either to do more of the same or to reconfigure your activities. This is particularly the case if other ETI engage in the sort of exponential trends our species is so very good at doing. If any ETI persist in doing much of the same they risk reaching some maximum entropy situation on their planet which could result in a mass die-off.

    I would certainly think that any ETI which survives for a relatively long time period after first developing technology they will do so by reigning in their appetites and configuring their technical infrastructure in ways more commensurate with their planetary environment. If in 500 years our species is doing well and not in a state of some post apocalyptic misery we will have done something similar. In some cases OF ETI they might after such a collapse manage to climb out of the disaster and build a future which is more commensurate with their planet.


    1. One of the most important resorces for intelligent civilizations is energy. We are currently polluting our atmosphere with the waste of burning fossil fuels. More advanced technologies will use renewable energy sources or nuclear fusion.

      But could some advanced civilization learned to make energy out of nothing by producing negative energy (like that between two thin plates, i.e. the casimir effect) ?

      With negative energy, you can make energy from nothing without violating the conservation of energy: create equal quantities of negative and positive energy.The net result is zero new energy.

      This is not new: the entire Universe is thought to have produced all the matter around us just after the Big Bang (during inflation). Currently, as the universe expands, more and more vacuum energy is created from nothing as space expands while the energy density remains almost constant.

      Has someone imagined to make a tiny perpetual motion machine (of the first kind)
      using the casimir effect as energy source as explained above?

      Could some ETI learned to use negative energy (like that of the casimir effect) to make arbitrarily high quantities of energy to power themselves without taking that energy from their environment (i.e. from their planets and stars), resulting in zero waste products?

      1. The Casimir effect is not a source of energy unless the universe has two regions with different energy level. One might think of the vacuum as a static body of water. The body of water has energy, but it can only be accessed if one can cause it to flow through a turbine and down to a lower level. The vacuum of the universe appears to be absolutely constant to the further regions we can observe. The GALEX results bear this out. The process of lowering the vacuum energy by separating two plates might be compared to lower the water level of a small region by pushing a floating body into the water. The buoyant force which opposes one’s force on the body is analogous to the Casimir force on the plates. If you let go of the floating body that buoyant force pushes it upwards and performs work. However, that work is equal to the energy you put into the system by pushing the body into the water. The same goes for the Casimir plates.

        If you could somehow grab vacuum energy and convert it to electrical current, by say dumping the vacuum to zero energy “elsewhere,” a one micron volume sphere would give enough energy to push an electron to 1 electron volt. You would need to do this to 10^{19} such volumes to get one volt, a region about 2 meters in radius. If you converted that much vacuum energy to power every second you would get one watt of power. Humanity generates about 10 trillion watts of power, which would require converting the vacuum energy in a volume which would enclose the orbit of Mars every second. So even if we could figure how to dump the vacuum into a complete zero energy state in some volume in a lab, it is clear this will never be a practical power source.


      2. If you burned all of the coal and all of the petroleum, then disassociated all the carbon dioxide from all the limestone in the entire planet’s crust, you still wouldn’t have gathered together all the CO2 that was in the atmosphere 1Gya.

        Good day.

      3. The Earth prior to 1.5 billion years ago had primarily a CO_2 atmosphere. Much of that carbon was sequestered by foraminifera and plankton in their shells and has gone into dolomite and limestone. If that carbon were released you can be sure a pretty good percentage of the primordial CO_2 in the atmosphere would be returned. The continent of Europe and much of North Africa is essentially limestone, the Egyptian pyramids are made of limestone. Imagine releasing all that CO_2!


      4. Um – yeah, and the Earth was a largely unlivable, inhospitable place 1Gya. What is your point?

      5. There is no such thing as free energy.
        Once your plates get stuck together by the Casimir effect you need to add new energy to separate them again.

      6. If we take it from the top:

        – We can’t have perpetual motion machines that generate energy, as lcrowell notes. That is thermodynamics 101.

        – The Casimir effects, static and dynamic, are already effective vacuum energy effects. We can’t get to the actual vacuum energy locally.

        – Over cosmological scales general relativity doesn’t preserve energy, you need to incorporate the whole universe for that. But those scales gets you energy loss, redshift of light, not energy gain.

        The house rules are:

        0. You must make a bet. (Thermodynamics 0th law of TD energy.)

        1. You can’t beat the bank. (TD 1st law of conservation of energy.)

        2. You can only loose. (TD 2nd law of entropy increase in closed systems.)

      7. There is the third law, you can’t quit the game. From a thermodynamic perspective it means you can’t reach zero temperature and avoid the second law. The 0-th law is a sort of inverse law, which is you can’t get to infinite temperature. In string theory this menas the upper temperature is the Hagedorn temperature.


      8. Hmmm perhaps there is an alternative to the energy question.
        Assumptions that a civilization can travel between stars and galaxies then there is an endless supply in the form of harvesting energy from stars.
        Stars burn for billions of years spewing out plasma and other materials and energy…. A ship that can withstand the harshness of space, it’s builders would realize this. The other stand out source for me is the strong force energy stored in the bonds of matter. Depositing the waste into the nearest star or black hole accretion disk…

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  4. What is interesting here is that one of the ideas often talked about in Panspermia, is the idea that advanced civilizations realize they cannot travel the stars, so instead they create bio-machines with DNA coded to carry out evolutionary changes in a guided way over time. That they colonize the universe with “star seeds” so to speak. Which is an interesting SCI FI book with a similar (though more technology based) idea.

    So this idea of Green Technology fits in nicely with that one theory. We could already be visited, or even be the products of these probes.

    What if for example humans are just some Alien Colonization tool? A way to make sure that the uniqueness of life in the universe doesn’t die out without a fighting chance?

    Anyway just food for thought.

    1. Are you referring to a book in particular? I could use a good read as I’ve always thought it would make an epic story arc to find out that we were the seeds of a previous generation. Similar to the movie Mission To Mars, but on a much grander scale.

      1. Sorry for taking so long, I don’t recall if it was a book or not, I think it was referenced in a website that endorses Panspermia as a theory that was really interesting to read. While some of the stuff was esoteric (talking about Gaia or something), the scientific stuff was relevant to this discussion – The main concept being that until we can PROVE that life formed here from the stuff present in the primordial earth, it is at least POSSIBLE that life on this world could have started elsewhere.

        Indeed, there is a lot of evidence that this is a MORE likely idea – No where else in nature does life just spontaneously form, life is always spread, in the forms of seeds or migration, from one place to another.

        Of course then the question becomes where did THAT life comes from.

        Anyway without taking sides on the issues presented here it’s good reading, be warned some of the stuff talked about on this link is esoteric in nature talking about the idea that life has always existed in the universe since the big bang, but was just in another form… –

    2. You can’t preserve biochemical machinery undamaged over astronomical distances. Nor would they be adapted to the local environment they land in.

      But sure, you can try to seed with evolving seeds.

  5. What an intriguing speculation! I do wish, however, that you would refer only to civilizations which are “older than we (are),” and completely ignore those which are “older than us.”

  6. With advanced molecular nanotechnology, there’s the potential to do many things (including material recycling) with efficiencies approaching their theoretical limits. That tends to make you ‘green,’ even if that wasn’t your goal…or if you’re a being that never heard of chlorophyll.

  7. This is an intriguing thought experiment. Lets take it to another level. (for fun)

    If; ”any sufficiently advanced technology is indistinguishable from nature,” Then one can posit that; nature is a technology.

    Rather then saying that ‘probes could be hidden by nature’ its also possible that biological life is a probe, it is certainly self replicating. It takes millions of years but biological life unequivocally terraforms its biosphere, in the long term aim of producing a BioSphere capable of supporting ‘complexity’advanced enough to become sentient and leave its home planet.

    Perhaps; quite simply, this how planets procreate.
    Lets posit this another way; You are not You, if you go to another planet you are taking a Microbiome of life with you.

    “Total microbial cells found in association with humans may exceed the total number of cells making up the human body by a factor of ten-to-one.”

    Lets take the idea even further, and posit that Stars, Planets and Solar Systems all the way to Galaxies are the most sophisticated types of technology possible in our universe.

    One possible sign of this could be that the Baryonic matter is organized everywhere to a remarkably similar design. If you can momentarily suspend the desire to know what it is and how it came to be, you could ask; What is it purpose?

    From my perspective Galaxies appear to be turning base interstellar hydrogen into complex matter, thats the best place to start the questions.

    Stars in turn produce planets that give rise to ever more complexity. Why? is it a waste product or engineered by design? Is life itself an accident of another sentient intelligence in the universe.? What function does small level complexity give to a galaxy anyway? Perhaps a form of data storage? A sub routine in the Galaxies thought process?

    How could we prove any of such concepts anyway?

    Perhaps the weak magnetic lines that permeate a galaxy transmit information like synapses in a brain. (think IBEX observations) but its highly improbable we would ever be able to detect such signals from the inside of our Galaxy. Perhaps the best hope we have is to see information exchange between distant galaxies. ? If they are constructed rather then a result of random chance then they should exchange information.

    My point is that If you accept nature as a developed technology and by extension that must include complex Baryonic matter from which its made, why continue to conceptualize an alien intelligence in anthropocentric terms and limit them to the extremely small time frame and scale we can conceptualize.

    Colony plants like the Quaking Aspen still living on earth are conjectured to be 80,000 years old years old or older.

    Perhaps it should be said that; If; ”any sufficiently advanced technology is indistinguishable from nature,” then its highly unlikely to find 4.5 billion years to be a long time. 🙂

    1. Again I have problem to understand the ideas, since they fail against what we know on nature. But here it is fractal failure, for example nature is obviously not a manufactured technology.

      – Planets can’t procreate. Life can procreate.

      – Large structure has no purpose, it is caused by primordial quantum fluctuations of cosmology.

      – Communication beyond a few light years are one-way only due to relativistic response time.

      1. Hi @Torbjörn Larsson

        It was just a brain dump to plain text.
        But Ill respond;

        “- Planets can’t procreate. Life can procreate. ”

        “All organisms and their inorganic surroundings on Earth are closely integrated to form a single and self-regulating complex system, maintaining the conditions for life on the planet.”

        Sure my abstraction is a leap of the imagination, but all life does tend towards procreation, devision, or genetic multiplication. Alternatively if biology is the “Self Replicating Probe” sent by an advanced civilization, wouldn’t its prime directive be to continue spreading itself to other planets?

        “- Large structure has no purpose, it is caused by primordial quantum fluctuations of cosmology.”

        Biological life clearly does utilize Quantum Fluctuations: What is biology’s purpose?
        By extension why not any complex system of Baryonic Matter ?

        “- Communication beyond a few light years are one-way only due to relativistic response time.”

        Richard Feynman once said, “I think I can safely say that nobody understands quantum mechanics.” I certainly do not either, but I can conjecture on the bits I do understand and posit something alien enough to be alien to me. Galaxies as constructs is about the limit of my imagination. The idea of detecting communication between galaxies is the only way I could think of us finding proof by a scientific method to such a notion.

  8. A similar rationale counters all of the “crashed UFO” stories circulating around, since we have already developed seat belts, airbags, and are working on self-driving autos (The autopilots on fly-by-wire aircraft won’t let the pilot fly into a stall, for example.). Any society advanced enough to fly to another solar system would likely have failsafe devices and redundancy as a basic part of their design. The idea of flying to another planet and then running off the road like a 1957 Buick would seem to be a bit counter-productive, to say the least.

  9. Indeed, any sufficiently advanced intelligent species may be beyond human understanding. Arthur C. Clarke and Stanley Kubrick demonstrated this principle in the much discussed ending to their movie “2001: A Space Odyssey”. Before his death, Clarke was questioned about what the last fifteen minutes of the movie really meant. He responded, “We’re you lost, incredibly confused, unable to make sense of it?” The questioner replied in the affirmative. “Then that’s what it would be like confronting an intelligent life form perhaps a million years ahead of humans.”

    So, it may be that no form of communication is possible with an ETI except during a very narrow range of its development. SETI, which has failed to produce results in over half a century, may very well be chasing its tail.

    1. Depends on what you mean by “understanding”. Observing life would be easy, their society and technology harder but doable on overall characteristics. (Using energy, say.)

      1. With all due respect, perhaps you are overestimating the current capabilities of our science. Do we really understand the nature of a singularity at the center of a black hole? No, because we can’t understand infinite density in zero volume – at least for now it has no real meaning in any frame of reference. All I’m saying is that a million years from now, our descendants, if you can call them that, might be incomprehensible to us. Positing the same for and ETI, if there be such, isn’t much of a leap.

  10. Speculation like this just shows that any theory that there is or isn’t intelligent life with advanced technology in the Universe has all the classical signs of unfalsifiability. You can make any lack of observed effects of LGMs fit either argument by suitable manipulation.

    The only way we will ever know is to catch one of the little buggers red handed. Or green handed.

    1. I agree on the general question, too many options. Specific hypotheses can be testable, especially if they get positive outcome (SETI).

  11. The reasoning is that if a civilization manages to exist that long, it would inevitably “go green” to such an extent that it would no longer leave any detectable waste products behind.

    Since this is so utterly erroneous, it is hard to make any sense of it.

    There isn’t anything “green” about nature.

    – We live in a poisonous, corrosive, flammable, utterly deadly atmosphere of oxygen waste left over by photosynthetic bacteria and plants. Those created mass extinctions on scales never seen before or after – when the atmosphere went oxygen and when oxygen swings deep froze Earth several times.

    – Similarly we live on waste heaps of calciferous and sulfurous sediments laid down by other life to the extent that continents are covered with it. Same goes for carbonaceous sediments, liquids and gases. Both of those have directly cause mass extinctions, the latter in the big Permian die off caused by the coal burning of the Siberian Traps, the former in the K-Pg Chixculub impact spreading such sediment into the atmosphere.

    – The premier waste product of life, oxygen, and to some extent nitrous oxides, are eminently detectable. This is exactly how we expect to find life like us.

    Nothing that we can do can make such big impacts on the geosphere and biosphere processes on Earth, because the initial damage or evolution took eons of time.

    – We can do specific damage like removing the ozone layer, but that has happened before, and GW warming, but that has happened before.

    – What we do then is doing it _faster_ than ever before, setting of mass extinctions because life has to adapt on previously unseen time scales. But it is highly doubtful those will be as large as the biosphere caused on itself per above.

    As all species we expend resources, but as opposed to them we can change resource base and go at it with a vengeance. Expanding out in the solar system will only increase resource consumption and increase visibility.

    1. Well said. I can only support this.

      May be, very advanced alien civilizations do not produce waste we are able to recognize (now). Or they only produce waste we are not able to recognize (now). But they may very well produce “non-waste” we are able to recognize in the future. And what’s about the not so very advanced alien civilizations?

      It’s always the same with the Fermi Paradox: endless arguments and counter-arguments.

      Talking about arguments, from reading what the science fiction writer Karl Schroeder shows on his website, I get the impression that his “reasoning” lacks arguments to a remarkable degree. It’s a good science fiction idea, but nothing else.

  12. I think it’s highly unlikely we are alone in the universe. As we’re seeing in the recent years, there are planets everywhere. A small part of them will have life. An even smaller part of them will have intelligent life. However this intelligent life will not be 100 years less advanced than us or 100 years more advanced than us. The difference will be in millions of years. We cannot comprehend what out technology will be in 1,000 years, let alone 1 million years.
    So I think there is no way for us to detect them other than visiting their planets. They on the other hand may have already detected us however other than being an alien tourist attraction, we serve no purpose to them.

  13. One thing everyone is forgetting:

    There might be lots of intelligent aliens out there, that did not “go green” and destroyed their ecosystems, meaning they are likely dead.

    There are also others that may have annihilated themselves through wars (nuclear, biological, chemical weapons)

    And there is a good chance that some of them got hit by an asteroid or comet and bought the farm.

    We may simply be lucky to have survived as long as we have.

  14. Puts a new spin on “Intelligent Design.” If sufficiently advanced tech is indistinguishable from nature, then there’s no objection to the assertion that nature is the product of design. Nature is categorically of a kind with technology. If photosynthesis, for example, originated as some civilization’s tech solution to a practical problem, then there goes the categorical distinction between organism and device. When we look at the night sky, what are those dots of light? Organisms whose metabolisms have evolved/developed from chemical to nuclear? see more at .

  15. I don’t know… the supposition that aliens exist but they’re just so advanced that we can’t detect them sounds a bit schizophrenic to me.

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