So Where Is ET, Anyway?

While having lunch with colleagues at Los Alamos National Labs in 1950, physicist Enrico Fermi mused about the likelihood of intelligent life existing elsewhere in the Universe.  Fermi, one of the most astute scientists of his day, thought the size and age of the Universe means many advanced civilizations should have already colonized the galaxy, just as humans colonized and explored the Earth.   But if such galaxy-wide extraterrestrial civilizations exist, he wondered, where are they?

Some believe this problem, called the Fermi Paradox, means advanced extraterrestrial societies are rare or nonexistent.  Others suggest they must destroy themselves before they move on to the stars.

But this week, Jacob D. Haqq-Misra and Seth D. Baum at Penn State University proposed another solution to the Fermi Paradox: that extraterrestrial civilizations haven’t colonized the galaxy because the exponential growth of a civilization required to do so is unsustainable.

The researchers call their idea the “Sustainability Solution”.  It states: “The absence of ETI (extra-terrestrial intelligence) observation can be explained by the possibility that exponential or other faster growth is not a sustainable development pattern for intelligent civilizations.”

The researchers base their conclusions on a study of civilizations on Earth.  Historically, rapid growth of societies means rapid resource depletion and environmental degradation, usually with dire results.  They cite the example of Easter Island, where resource depletion likely caused a collapse of the local population.  And they conclude that while there are examples of sustainable growth like the !Kung San people of the Kalahari Desert, exponential growth in population and spatial expansion of a society is almost always linked to unsustainable growth and eventual collapse.

This principle has implications for our current global civilization.  Since Earth’s resources are finite and it receives solar radiation at a constant rate, human civilization cannot sustain an indefinite, exponential growth.  But even if we survive and advance as a civilization, we may have trouble colonizing the galaxy should we ever decide to do so.  And if this limitation applies to us, it may apply to other civilizations as well.

But the Sustainability Solution doesn’t mean ET is not out there.  Slower-growth extraterrestrial societies might still communicate by radio or other wavelengths, so current SETI programs still make sense.  Or ETI may result in chemical bio-markers in planetary atmospheres which may leave spectroscopic signatures detectable with upcoming generations of Earth and space-based planet-hunting telescopes.

The Sustainability Solution also allows that advanced civilizations may indeed colonize the galaxy, then collapse as resources are consumed at an unsustainable rate.

And some civilizations may send small messenger probes to other stars, which suggests a search for extraterrestrial artifacts (SETA) within our own solar system might be just as fruitful as radio-based SETI.  Searches might involve radio or visible detection of extraterrestrial probes orbiting the sun.  Or artifacts may even be embedded within planets or moons of our solar system, just like the giant black monoliths in Arthur C. Clarke’s 2001: A Space Odyssey.

In any case, the discovery of artifacts from a slow-growth extraterrestrial civilization would be an example “sustainable development” on a galactic scale.

You can read the original article here.

25 Replies to “So Where Is ET, Anyway?”

  1. I brought theses issues up under the ‘NASA gives truth about UO videos, namely: “On a closely related note, 2 Penn state researchers just released a paper entitled ‘The Sustainability Solution to the Fermi Paradox’ (The Fermi Paradox is basically saying that if intelligent extraterrestial life exists, where is it? We should have detected it or have been visited by now. See Wiki for an excellent overview). Anyway, the authors conclude that “The Fermi Paradox cannot logically conclude that humans are the only intelligent civilization in the galaxy.” This short, nontechnical paper can be found here: . The authors explain their ‘Sustainability Solution’ and bring up good points for future SETI searches.”. Also: “My take on the paper I linked to was that the authors started out using anthropocentric assumptions on alien ETI as sort of a baseline and from there derived their assertion that the Fermi Paradox cannot be used as an argument against ETI in our galaxy. Indeed, the authors state “After all, there are many explanations for the absence of ETI civilization” (pg. 7) and “…we cannot rule out the possibility that ETI civilizations may follow a development pattern sufficiently different that we wouldn’t recognize it even if we detected its signal” (pg. 10). So it would seem that totally alien civilizations and their development would not be precluded or conflict with their proposition. This paper presented some thought-provoking dialog on the issue of ETI and the consequences and strategies of future SETI research (I noted their spotlight on the possible detection of past brushes with ETI within the Solar System, sure to get the attention of ‘UFOlogists’. Sorry, no detections yet, according to this paper, just an extrapolation of their arguments).

  2. Do’h. Erratum: read “these issues” and “about UFO videos” where appropriate.

  3. Of course, belated thanks to Brian Ventrudo for expanding and reporting on this thought-provoking paper !

  4. I’ve always considered the Fermi Paradox to be bunk. Since we know of zero civilizations capable of colonizing other planets outside their own star system (our civilization can’t do it), what is the basis for predicting the rate at which such civilizations should have colonized the galaxy over its 10-billion year history?

  5. The idea of an artifact hunt for alien relics is one of immeasurable fascination to me. The Earth’s Oceans are littered with remnants of our failed ventures into the unknown, a sufficiently advanced civilization would certainly have peppered the cosmos with evidence of their past forays into the vastness of space.

    The notion set’s the imagination alight. consider the marvel of such a discovery, but what sort of calling card might an alien culture leave behind and how would they ensure it’s longevity in face of a dynamic environment?

    If Humanity is indeed the sole bastion of intelligence in our corner of the galaxy, then it redoubles the imperative that we find a sustainable mechanism by which to advance our race.

  6. My gut feeling is our lack of a unifying theory affects our search for ETI’s.

    Not much point in speculating on how that might affect our search, but it stands to reason that until a civilization arrives at such a juncture it is unlikely to progress far out of its solar system.

    A though experiment for you all; If a microscopic organism living on one persons head were to become self aware and build a technologically advanced society, would it come to the realization it was living on a larger sentient being?

    Lets not forget our sense of scale in our search, we happen to exist in a very large universe.

    Damian K

  7. If we consider ourselves as any example to go by, then there is very little likelihood of “civilisation”s reaching further than their own star system since they will have squandered their resources on warfare and SUVs long before achieving the technology to advance into interstellar travel.
    (..or to have depleted all the matter of their system to build a Dyson-sphere or some such white elephant…)
    A very ancient “message in a bottle” is all we may ever see (or send), by whatever means detected, at our current primitive state of technologies and organisation.

    Remembering that the further we look the further back in time we are viewing, it would therefore seem logical that, assuming a given time to allow evolution and development, the chances of finding signs of ETI are more probable in closer temporal-proximity to ourselves.. say, within our galaxy

    The only other metaphor of what could travel intra-galactic distances would be a “seed”… propogation , not communication.

    We are looking for smoke-signals presently, but new ideas like detecting bio-marker chemistry are broadening our approach.
    Let’s cool our imaginations a wee bit, forget the Hollywood franchises, and establish the existence of biology elsewhere, progressively refining the search to ‘higher’ forms of life as we may with new discoveries as we find them.
    The finding of an indigenous microbe on Mars or elsewhere in our Solar system is arguably more probable a proof that “we are not alone” than receiving an ET email.

    The discernment of Earthlike planets existing in “the habitable zone” is also on the soon to be achieved agenda.

    While SETI is worthwhile, let’s not get fixated on ET like Lowell on Schiaparelli ‘s “canals”.
    Let’s apply Ockham’s Razor to Fermi’s “paradox” (sic).

    Instead of second-guessing what an advanced intelligence might have done were it to have had a civilisation extrapolated on our own present one, let’s keep looking for evidence of the kind known to have existed for billions of years right here on Earth… simple ‘Life’… biology.

    ‘Intelligence’ is altogether a fraught term as ill defined and as tendencious as ‘civilisation’.
    .Not all peoples embraced technologies like those now dominant on our planet. Some, no less intelligent than any US citizen today, lived tens of thousands of years without changing technology, while others who ‘advanced’ their’s flourished and perished in a matter of a few centuries.
    One, longer lasting but harder to differentiate from the ‘background’ biology, the other fleetingly conspicuous, but then nothing left but ruin engulfed by the ‘background’ biology…..

    In the history of Earth we are the last split-second… so might we expect any ET to have been in their own time on their own planet.

    Remembering the time-differential of all the observations we are making, compared to their source, naive it would be to expect an easy encounter with another communicative, technologically-similar, and similarly motivated life-form to coincide with our just-now-achieved means and interest in doing so!

    And sadly, I think this gullibility is driven by nothing more than the narcissism of seeking a ‘mirror’ of ourselves, to justify ourselves, much as is the root of religious belief-systems and the credoes of other hierarchical orders. We will remain unheedingly blind to the intelligence all around us , near and far, solong as we cultivate that obsession.

    Cheers to the author, the article and to all those sincerely addressed to the genuine resolution of these grand questions.
    I’ll forgive Fermi, and assume a flippant aside of his was co-opted by others to serve their own (dis)respective agenda. 😉

  8. The quality of this paper is abysmal. The resort to formal logic (never mind the lacking logic of the paper itself) reminds me of high schoolers trying to dress up attempts of authorship. To paraphrase what was said on the abysmal writings of crackpot Smolin thread (also authored by Ventrudo; is this a coincidence?), you read this and then you die a little inside.

    [Disclaimer: As opposed to the other thread commenter, I’m not claiming to study SETI. But I have authored papers.]

    The paper confuses several different subjects. For example, there is a difference between observing communications and other artifacts, as well as a basic difference between a communal civilization and a colonizing one. As we can’t achieve light speed, there will never be any form of economical matter trading between stellar habitats.

    Further, as species lifetime is typically 100 000 years and the galaxy colonization time at least an order of magnitude larger than that, there will never be a species specific “galaxy-wide civilization”. Even if the dispersal front can be maintained as a species by using relativistic effects, the older areas will inevitably evolve away.

    This confusion seems to be at the front when claiming that “exponential growth” is non-sustainable. There is a decisive difference between exponential economical growth and exponential colonization, the latter of which merely depends on population increase. Thus I can’t see how their main proposal, “The “Sustainability Solution”” constitutes a prediction..

    I’m not a big fan of, mostly, untested Malthusean population models.

    For example, they don’t consider markets and technological improvements as economists include. In biology these so called r/K-models are useful heuristic devices to distinguish between species behavior but controversial and untested as to this specific mechanism; in other areas such as “peak oil” they fail to explain observations.

    Instead I think falsifiable Drake equation models has a lot going for them, especially now when the discoveries of exoplanets have moved them from bayesian learning probabilities into traditional predictive frequentist constraints.

    Ironically the paper shirks from the testable basis of the area, and finishes off by including an untestable bayesian claim on the “need for sustainable development”.

  9. Oh, I guess I need to propose my own ideas on ths topic instead of mere criticism. [But again, the disclaimer: I haven’t studied this.]

    As regards the related “Great Silence”/communication topic of SETI, it seems to me Seth Shostak is on the money when he claims that not enough stars have been surveyed. By his data and a Drake model, his estimate of a conclusive test of the prediction by 2020 seems to me to be in the correct ball park, albeit perhaps optimistically so.

    As regards other artifacts, it seems to me we don’t know enough.

    For example, biosphere population models (non-Malthusean ;-)) can explain the absence of traces by synchronizing biosphere ages by medium scale, low frequency catastrophic events such as supernovas or GRBs. (I have a reference paper among my bookmarks if someone is interested.) In such a case there can be a lack of colonizing civilizations within our “colonizing” neighborhood as of yet.

    In such a case it also hampers SETI somewhat, of course. Unless colonization is as fiercely difficult as it seems a priori. Ideally that would then explain observations if we would see ETI by communication but not colonization.

  10. “test of the prediction” – that would be the prediction of civilizations of lifetime of a typical species. (Assuming earth species lifetime as a measure of species lifetime of evolution in general isn’t much of a jump IMO.)

    Shorter lifetimes demands further observation.

  11. Oh, I completely forgot to check up on the authors. “Department of Meteorology & Astrobiology Research Center” ( Haqq-Misra). “Department of Geography & Rock Ethics Institute” (Baum). WTF WTF?

    Turns out that Penn State University has a Department of Geography dedicated to “subjects of inquiry in the natural, social, information sciences, and humanities”. The above ethics institute is indeed listed as a “Liberal Arts” department, who have a professor of Philosophy (Nancy Tuana) as Director. Tuana gave 2008 a seminar in “Ethical dimensions of climate change”.

    No wonder then that a “Sustainability Solution” is proposed. Even though it seems to be vapor-ware and isn’t proposed in a scientifically sustainable way. 😮

  12. It seems to me that ETI has existed, does exist and will, in future, exist. The sheer size and diversity of the universe would make me a foolish gambler indeed to bet against it.
    On the other hand, the sheer size of the universe means that life is so sparsely distributed that our chances of detecting it are very low, and of meeting it effectively nil.
    To say that civilisations burn themselves out is pure speculation, and indeed contrary to the evidence: We only know about one civilisation and, despite some heinous mistakes and some localised waxing and waning of subgroups, we are still limping along.

  13. I agree with the conclusion of these authors. Intelligent life will consume resources and learn about the nuclear bomb. They will then likely put themselves in a situation where they must either control their activities or perish. This means that exponential growth into the world outside their home bio-planet is unlikely and expansion beyond ever less likely.

    We are clearly faced with the same problem.

    Lawrence B. Crowell

  14. This is utter garbage for this very simple reason:

    “The researchers base their conclusions on a study of civilizations on Earth. Historically, rapid growth of societies means rapid resource depletion and environmental degradation, usually with dire results…”

    The incredible fallacy here is that their theory is based on resource depletion of a finite Earth. While what we’re actually talking about are boundless resources in a nearly infinite universe.

    Noted physicist Michio Kaku has indicated multiple times that when a civilization becomes advanced enough to colonize multiple worlds, resource depletion is no longer a problem.


  15. Jim Krug, great post.

    I’m always amazed at how closed minded some individuals are with respect to the chance of advanced life. They always base it on or compare it to us and that is a very flawed thing to do IMHO. For example, an alien species that is a couple hundred thousand years older than us and thus a couple hundred thousand years more advanced in technology would have likely developed a far more advanced method of communication than we are capable of even picking up. Given the age of the universe, it’s likely there are some that are even millions or billions of years older than us.

    And if they had a learning curve comparable to us, imagine how far along they would be. But what if they had a much sharper learning curve? A species that is fundamentally far smarter than us from birth, might not even have to be thousands, or even millions of years older than us to be way ahead of us and psychologically be totally different than us and NOT waste resources like we do.

    I think it is the height of ignorance and arrogance for us to think that any advanced species would in any way be detectable via our technology. It’s even more arrogant and ignorant to belittle the possibilities of advanced life because we haven’t detected in the in the extremely tiny amount of time we have been capable of picking up certain signs of life.

  16. @ Torbjorn Larsson OM, could you please supply your references to the statements you posted above, namely ” …as[sic] species lifetime is typically 100 000 years” and “the galaxy colonization time [is] at least an order of magnitude larger than that [the species lifetime]” ? You also mention a paper you have bookmarked that “can explain the absence of traces by synchronizing biosphere ages by medium scale, low frequency catastrophic events such as supernovas or GRBs”. Could you kindly direct me to copy of this paper ? It seems most of the people posting on this story do believe in Extra Terrestrial Intelligence, but have differing opinions as to the details. Great! Science thrives among valid, informed debate. Quite an interesting discussion. (Btw, I find myself drawn to Crowell’s interpretation of the paper, but, hey, to each his own 🙂 ).

  17. Nice article Brian.

    I read this paper too. The paper’s content seems amateur compared to other research papers. There is an Astrobiology institute at Penn State, but the other writer is from their Ethics institute. Once I knew that piece of information, I was read this with a good dose of healthy skepticism.

  18. I think the reason we haven’t communicated with anyone is because we are looking for aliens that are like us.

    I’m willing to bet that alien life forms, even intelligent one might look, behave and communicate in ways that are truely *alien*.

    They may communicate via magnetism, neutrinos, or spitballs. They might be right next door, but simply speaking a very different language.

    As far as the sustainability issue, I’m thinking there might be just as any variables. For example, they might have colonized their moon or a nearby planet that has loads of resources, including raw materials for space vessels or probes.

    Then again, they might have already nuked themselves.

  19. I would echo Jon’s question to Torbjorn — he slams the paper but then introduces his own completely unsubstantiated claim that a species’ lifetime is one 100,000 years. I assume he means an intelligent species, but since we are very much still around I fail to see how any prediction of species lifespan can be anything more than a complete guess.

  20. On the other hand, Jim hits on what I think is the biggest weakness of the paper. The authors spend time talking about historical scenarios from Earth’s history, but completely fail to make the case that the same things can happen to ETIs that have begun to expand beyond the orbit of their own planet, let alone beyond their own solar system.

    The travel time and difficulty of establishing new colonies (and their subsequent isolation) would seem to be far more important than any concerns over exponential growth.

    In addition, given the timescales involved (600k yrs or more) in colonizing the galaxy, there is the possibility that a species may just find it easier to evolve beyond the need for expansionist policies.

    For example, if the only way to cheat death is to download your consciousness into an Artificial Intelligence construct, then perhaps living out your extended life in an infinite variety of cyberspace-created fantasies (think “The Matrix” except that you are in control of your own artificial reality) is more compelling that the real universe outside.

    In such a scenario, further space exploration would be done merely out of curiosity to see what else is out there rather than for colonization and conquest. Thus if ETIs reach Earth, they would be more likely to quietly observe rather than interfere with our development.

    Who knows? There is an infinite variety of possibilities. Sustainable development may well be one of them, but I don’t believe the authors do enough to make a very strong case for it.

  21. This matter I don’t think can be mathematically analyzed particularly. Yet a few suggestions could be made. If we get a radio signal from ET, or a spacecraft from them makes it here clearly they have at least some parallels to us. Such intelligent life is able to solve problems, which means that they can remove any environmental constraints on them. Homo sapiens started this about 4 million years ago when australeopithicus took themselves off the menu (throwing rocks at leapords etc) and figured how to get more on their plate. Then can stone tools, fire, and so forth. With each of these advances our homonid ancestors liberated themselves from the negative impact of the biological world around them, and learned to exploit more of that world.

    The result in our case is that we have expanded our population and control over the planet in unprecidented ways. it is the way of biological species, they largely are controlled in their dominion over the environment by the action of other species, preditors, parasites, etc. Yet we can figure our way around them. This is the nature of biology, and maybe any alternative self-regulating chemical system similar to life: they push to expand their influence and energy access. I would well imagine that any ET out there might well enough do much the same as we have.

    E.O Wilson wrote about the bottleneck the human race faces in the future. In a nutshell we are similar to the demonstration where a mold or bacillus on an agar plate grows and consumes its medium until there is a black crisp of waste left. We are in a much larger and complex manner following a nearly identical course — rather than using up agar on a plate we are using up the biological and mineral wealth of this planet. It would not surprise me at all if the vast majority of ETs that are technological do much the same.

  22. This is not really a new idea. It’s been kicked around in several SF novels/short stories (For the best example, see RAMA REVEALED by Arthur C. Clarke (and please forgive the lack of title–I would rather leave it off than put something on that would be incorrect and offensive).

    Painting the properties of intelligent life with one brush stroke seems to me a bit foolish. Just as terran fauna comes in a myriad of forms, I suspect the same for sapience.

    As regards the original article, I find it reporting on a paper that is overly pessimistic, and narrowly focused on human failures. Anyone who has studied demographics will admit that WRT population growth, once a high standard of living is achieved in a society, birthrate drops off precipitously.

    Additionally, we are slowly learning how to control the consumption of our resources, not to mention that we have barely begun to tap the resources of the whole solar system. Ditto for our passions. I have said in other places that I suspect we have a critical 100 years to get through, and then we will enter a golden age.

    As to the original question, “Where are They?” We still have several good possible explanations:

    1.) We’re alone (not a popular explanation, but what does science have to do with popularity?)

    2.) They’re out there but they use a different form of communication.

    3.) They’re out there but they choose not to communicate with us barbarians.

    4.) They’re out there, friendly, chatty and willing to share, but we haven’t come across them yet.


  23. I tend to agree with Pedantic although I go much more for (1) as I have been convinced for years that Fermi Paradox leds to the conclusion we are alone or among the first.

    Not I do I think much of these writers comments that today “Amazon Basin, Siberia, and Indonesian islands are largely untouched by the global human civilization.”

  24. I’m with bernardz, if the galactic age is considered correct, we are among the first, therefore effectively alone.
    If galactic age is assumed as incorrect (that is, greater than current thought) then considering the size of the universe and difficulty in performing said travel you can chose any of 2 – 4 from pedantic’s post.
    Also, considering Sagan’s great mathematical postulation about the probable number of civilisations out there, that needs to be measured against the size, again we come back to being alone, at least in this quadrant/area/locale/whatever.
    So, to go back to whether expansion is limited by sustainability, who knows? How would other civilisations consume or utlise resources? How can we even guess? As already noted above, how can we consider or even be able to understand an alien civilisation when we have a hard enough time understanding ourselves?
    So, again from pedantic above, go for option (1) as unpopular as it seems, but make the most of what we have and keep looking anyway. Who knows what you might find!

  25. I tend to think that the density of intelligent-technologically capable life is fairly low. So the ratio of ET per galaxy is maybe at best around one at any given time of the Hubble frame. So if we humans mangage to contact an ET it might be a matter of great fortune and coincidence.

    Some issues have been raised about identifying exactly what is intelligent life. The objection is made that all of this involves comparisons to oursleves that might be wrong. In one sense I would agree, and in fact we do have what might be called other intelligent species here on Earth. Compare the brains of humans with dolphins, their brains are larger and more complex. Cetacians in general might be regarded as intelligent life, but their intelligence is different from ours. Then there are cephalopods, where some species of octopi have brains the size of basket balls which constitute 1/4 their body mass. These guys have complex communication by skin color and are capable of quick problem soliving skills. Yet they are not social and are short lived.

    I estimate the galaxy might have a few thousand bio-planets at any time, where maybe some subset of these have complex life forms. So there might be some intelligent life form on a planet just 500 light years from here that communicates to each other forms of mathematics we can’t imagine. Yet they might also not have the ability to manipulate things (such as whales etc) and so are not technological. We are likely to never know about them.

    Any technologically capable ET is likely to have developed those skills largely as a way to access energy and material from their environment, much as we have. The ability to communicate across great distances will also likely be a sort of indirect by product and not a primary focus of their activities.

    Lawrence B. Crowell

Comments are closed.