Thinking About Fermi’s Paradox

As the story goes, famed physicist Enrico Fermi looked up one starry night, noticed thousands of visible stars and the billions more they represent, and wondered “Where is everybody?

If the physicist knew then what we know today, might he have asked that famous question? Fermi, who died in 1954, certainly missed a lot of recent developements in the field.

For no particular reason, I have been mulling that over quite a bit lately. I can construct a fairly detailed argument that:

a) life is not all that rare in the universe; indeed, it may be relatively common.

b) intelligent, technologically advanced life, OTOH, may be exceedingly rare.

As an exercise, I started jotting down a list of things that made Earth if not unique, then at least the result of a relatively rare sequence of events that perhaps makes it a somewhat special. Size, solar system sweet spot, non-binary star, galactic location, core composition, magnetic field, rotation, axis, moon, etc.

I was most of the way through assembling my list when in my research I stumbled across a book titled of all things, Rare Earth: Why Complex Life is Uncommon in the Universe.

Written by paleontologist Peter Ward and astronomer Donald Brownlee. They make the case in far greater detail than I could ever assemble that complex life is indeed uncommon in the universe. My list making was brought to a halt, and I just ordered the book.

I had never heard of the Rare Earth thesis before — has anyone else? Regardless, it appears consistent with much of what we have learned about cosmology since Fermi’s death.

I am curious:

What interesting issues, questions, theses – outside of your chosen profession, expertise, or area of study – are you thinking about?


Print Friendly, PDF & Email

What's been said:

Discussions found on the web:
  1. VennData commented on Sep 9

    You’re saying no Betazoid nookie?

    Defund NASA!

  2. Iamthe50percent commented on Sep 9

    Yes, I heard of it long ago. Just another stab at maintaining the illusion of central position and with religious overtones. They borrow the same arguments as Creationists.

    (Funny how a human being is too complex not to be created by God, but God is simple enough to have arisen spontaneously. Or is there an infinite chain of deities?)

    • Jojo commented on Sep 10

      You asked and you shall receive… [lol]
      Welcome to Godchecker
      We have more Gods than you can shake a stick at.

      Our legendary mythology encyclopedia now includes nearly four thousand weird and wonderful Gods, Supreme Beings, Demons, Spirits and Fabulous Beasts from all over the world. Explore ancient legends and folklore, and discover Gods of everything from Fertility to Fluff with Godchecker…

  3. Dean commented on Sep 9

    I heard about it a couple of months ago from here:

    His writing style different but accessible, and it’s a great launch point for the mind-bending thought exercises like you mention. Also see posts on SpaceX/Mars colonization and AI.

    • Jojo commented on Sep 12

      Great article and site! Thanks!!

  4. webmartians commented on Sep 9

    There’s an unanswered question in astrophysics: just where did our Sun come from? Although we have but limited data, it appears that our solar system has a greater abundance of heavier elements than the systems of “nearby” stars. Does that mean that it formed somewhere quite different from the birthing regions of our neighbors?

    Was good ol’ Sol somehow flung outward from the galactic center?

    We’re pretty certain that at the Milky Way’s core is an enormous black hole, and that “beast” is spewing frightening amounts of radiation. From our current galactic position, we cannot observe directly that hellish maelstrom: our view is blocked by clouds of dust … and those are shielding us from much of the core’s emissions.

    So … our home is different and it’s protected. No wonder Enrico Fermi’s little-green-men haven’t shown up: they’re dead.

    • Science Bitches! commented on Sep 10

      First generation stars have almost none of the heavy metals — they are mostly Hydrogen, Helium, Carbon, etc. is the result of their novas.

      2nd generation stars that come out of the post supernovae nurseries can create heavier elements — iron, gold, etc.

      3rd gen stars lead to what we see today — more complex, heavier atoms, rare earths. etc.

  5. Singmaster commented on Sep 10

    What will people do when robots perform most jobs? Will there be enough new jobs? Or permanent leisure? Or dystopian divide between Haves and Havenots?

    How does the form and structure of classic rock and rock, the Beatles for example, compare and contrast with traditional concert music?
    A sonata by Mozart may sound completely different from one composed by Haydn but their structure, the forms they follow are the same.
    Where does rock and roll fit into it? Is it rondo form? Or other? Or is it completely different?

    When my local crows disappear for several days, where do they go? What are they off doing?

  6. Jojo commented on Sep 10

    As an SF aficionado, I have been aware of rare earth hypothesis for some time. While it does seem to make some sense when taken as a whole, is it really any better than the Ancient Alien stuff that also seems to make sense (although I still want to know why, after all these supposed alien visits and fights they had in our skies, why no one has been able to find even ONE piece of truly alien debris).

    Perhaps we really are the one successful, intelligent race that developed in the whole universe, but that is making quite the jump from the very limited perspective that we have as a single planet bound race who has yet to send humans beyond our moon, a mere 250k miles away. Maybe aliens ARE watching us develop?

    Anyway, our galaxy is huge and there are trillions of galaxies of all varied sizes in our universe. But it is not just size that needs to be considered. There is also time, which in our universe is around 14 billion years.

    Given that civilizations lifetimes might run anywhere between a few thousand to a few hundred thousand years, there is ample time for many other civilizations in our galaxy alone to have come and gone. Perhaps intelligent life is rare enough that only one such civilization exists at any one point in time? Perhaps the galaxy is littered with remnants of past intelligent civilizations?

    We just need for someone to discover a way to travel between stars (or even galaxies) in reasonable time periods. I would not be surprised (even though I will likely be dead) if some sort of warp engine that bends space is discovered in the next few hundred years. Huge advances are being made in physics and science in general. Think how far we have come in the last 200 years!

  7. Publius commented on Sep 10

    I do wonder about consciousness. To be specific, life isn’t rare at all on Earth. But consciousness is. There are zillions of species on our planet, and they fill niches faster than ETFs can be created. But only one species is self-aware, producing language, literature, and economists. Why? What is it about humanity that makes consciousness possible?

    • Jojo commented on Sep 10

      I am interested in consciousness also and what produces it.

      However, I think that all life is self-aware and therefore possesses some form of consciousness. The production of (or use) of language, literature and economists are not necessary to consider something being conscious.

  8. adrian.who commented on Sep 10

    @What […] are you thinking about?
    – How does the human mind work? For me, this is the ultimate question, because by understanding that we can have the answers for other important, interesting and mind-bending questions (and with a certain degree of accuracy, we already know some answers): Who am I? (a connectome), Do I have free will? (no, any choice I make it’s the only choice I could have made; next time the universe will be in the exact state, I will make the exact decision again) Is self an illusion? (via Sam Harris – yes; you are not the sensor feeling/detecting a sensation, but the sensation itself; the sense of the thinker of the thoughts in addition to the thoughts, is false) What’s the nature of human consciousness? Will we be able to transfer the human mind in a computer?
    – How did all this start? How did the universe begin? Is it finite or infinite?
    – How do the markets work? (tragically and ironically, this is in a big way inside my area of study, but outside my expertise :P)
    – Isn’t it the absolute proof of love that god sent his son to die for us, so that almighty god can forgive the sins we didn’t commit? – just kidding

    Ok… first 2 are pure scientific topics, 3rd is more my personal problem with Mr Market – still, the markets has to be governed by the laws of the universe, too.

    But I try to be aware of the trap philosophers fall into. Just for the fun of it, I can sit in my armchair and think about these, or I can have debates with friends (and I live in a country where, at the latest polls, only 1% said they were atheists, so you can imagine my infinite debate opportunities). But by definition, on any scientific matter that is outside my expertise, the only thing I can do is to listen to what scientists have to say. And how does a certain part of the universe work, is a scientific question – meaning it can and, let’s be optimists (No problem can withstand the assault of sustained thinking. – Voltaire), will be answered using the scientific method.

    But, let’s speculate for the sake of speculation and of human curiosity. Barry, what do you think? Is the universe deterministic? A sufficient complex machine could have analyzed the primordial soup of particles fractions of seconds after the Big Bang, and determined that there would be a planet Earth in a Milky Way galaxy, at some point inhabited by an intelligent civilization that would create such a thing like the internet, and you would post this exact question on your blog and I would give you this exact answer?

  9. Science Bitches! commented on Sep 10

    Wait but Why has a very long discussion on the subject, taking Fermi’s position.

    Its a million monkeys typing for a million years kind of argument — I doubt you will find it persuasive.

  10. NoKidding commented on Sep 10

    Is it within present day technology to destroy all life on earth? I can’t see any way it could be done.

    So how far could humanity go, in a unified, concerted effort, to euthanize earth? Could all mammals be wiped from all corners? Reptiles? Birds? I still doubt.

    How far could the food chain be erased? Platypus, Kuala, Panda sound easy. Owls? maybe. Mice? Sounds impossible.

  11. Denis Drew commented on Sep 10

    Rare earth angle: for the last 260 million years there has been a mass die off of species every 26 million years (we are about half way through the cycle). Suspected is a star whose gravity throws our Ort comet cloud out of shape as it travels by. That may have speeded up evolution to intelligence — dinosaurs to mammals one example. ???

    In any case look at your HD screen, extrapolate another 100 years of communications progress and why would anybody want to travel (for hundreds or thousands of years) across the void for things that can be fully experienced right here. Fermi didn’t have television.

    A physicist on TV offered that fish and birds on other planets would look the same because the physics of their movement would be the same — even if their underlying biology were very different. I would hazard that much life elsewhere would resemble life here. For sure the table of elements would be the same everywhere — making gold v. bimetallism debate a stage of economic development everywhere. The dismal universe? Who might want to travel around? :-)

    • noncist commented on Sep 10

      I tend to agree with this perspective.

      The force and time required to move a living intelligent body across the universe is enormous, even if you can accelerate to basically the speed of light, because you have to accelerate slowly enough not to die.

      An advanced interstellar civilization would probably spend most of their time in amazing virtual worlds that they created sending only robotic probes across the universe. They would use lightweight, efficient communication that would be hard to detect, not the broadcast systems we used in the 20th century. They could interact with far reaches of the universe through these probes, but they would probably not move their bodies far without a very good reason. Why leave the safety of a cozy, energy-rich Dyson sphere?

  12. GeorgeBurnsWasRight commented on Sep 10

    I find the “rare universe” concept more interesting. When you’re talking about hundreds of billions of galaxies each with hundreds of billions of stars, and we now know that planets are common, not rare, if even a tiny percentage of planets have intelligent life that’s still going to mean many millions of intelligent species. And given the huge lifetime of the universe, we can’t be anywhere near the first intelligent species to evolve.

    Under what I’m calling “rare universe” are some basic constants such as the force of gravity. Somehow our universe has just the right amount of gravity. Increase it by much and everything collapse, reduce it by much and nothing solid forms. It’s been quite a while since I read a book by an English scientist who lists 6 major constants in our universe and shows how each have a narrow range under which life can form. (Book is “Just Six Numbers” by Martin Rees.) Really the only satisfactory explanation to Rees’ six numbers is to assume that there’s an infinite number of universes, a theory which is currently beyond science to prove or disprove.

    • NoKidding commented on Sep 10

      A depressing corollary to your assumption “we can’t be anywhere near the first intelligent species to evolve”. Either:

      1) It is impossible for our extra-solar peers to contact us!
      2) Our extra-solar peers do not want to contact us!
      3) or the conspiracy is real!

      If you buy the “4 billion year old earth” and “plentiful intelligent life”, odds for an option 4 approach zero.

      The falsification of unfalsifiable science:

      a) Earlier BP article, its nearly impossible we’re not a computer simulation.
      b) Assumption of this article, life evolved through replicatable biological coincidence.
      c) Multiverse physics (cribbed from 1980’s comic books), we are simulations in a computer created by an evolved race that lives in a simulated universe, and we’re only one atom different than independent simulations in a computer created by an evolved race that lives in another simulated universe.

  13. trailhead commented on Sep 10

    In response to the actual question posed, I have been trying to get my head around quantum physics, particularly the notion of particle entanglement, as I feel I can longer ignore it due to recent advances. I also wonder what role it may play in the phenomenon of consciousness and our perception of free will.

  14. RiverboatGambler commented on Sep 10

    Thinking about:

    –Are good intentions or good results more important for doing what is right (regardless of the moral lens)

    –The end times of capitalism, when all capital has beget capital and is held by very few. Capitalism is the worst system except all the others, but it is not a state that works once it fully plays out. What do we do then?

    • NoKidding commented on Sep 10

      Will capitalism be destroyed by unlimited supply?

  15. constantnormal commented on Sep 10

    The fraction of our galaxy not exposed to gamma ray bursts is pretty small, and sooner or later, one will zap us (at least one of the Great Extinctions is hypothesized to be due to a gamma ray burst), so life must evolve (probably multiple times) to sentience (or something close to sentience, as we may be), build a technological civilization (there are paths that do not result in this), and last long enough (without destroying themselves by wars, overpopulation, destroying their ecosystems by a variety of means) to overlap the existence of other such instances within our galaxy, and arrive at technologies compatible enough to communicate. The odds are pretty low, considering that for thousands of years of human civilization we could have had aliens sending us “is anyone there?” signals (laser, radio, tachyons, gravitons, …) that we were/are totally unprepared to detect (if we were even looking).

    But even if the odds of us finding intelligent life that we can communicate with in our galaxy (remember that a message is going to take thousands of years to get from most points in our galaxy to here) are slim, the Universe is immeasurably larger, and there are certainly many intelligent civilizations out there, separated by only millions of years of speed-of-light travel time.

    Don’t wait up for the message.

  16. rd commented on Sep 10

    Given with our experience with conquest, it is a good bet that advanced civilizations have figured out it is smart to stay quiet.

    The Portuguese, Spanish, French, Dutch, and English would probably have invaded the Americas much earlier than 1492 if the Americans had figured out how to send communications to them informing them that there was an entire continent much closer than China.

  17. Event_horizon commented on Sep 10

    As one of the posters above mentioned, the Wikipedia entry on Fermi’s Paradox is excellent and worth the read. I think that Von Neumann or Bracewell probes would be the most likely way advanced civilizations would explore the universe for other intelligent life. Perhaps they serve only for passive observation, sending information back through the chain of other probes.

  18. Bob Fauteux commented on Sep 10

    Barry, you may enjoy the first and second (especially in re your topic above) of The Economist’s current series on “unsolved scientific mysteries”—1 How did biology begin?—Life story—In the first of a series of six briefs looking at unsolved scientific mysteries we ask how living things got going and whether they exist elsewhere than Earth | The Economist 8 Aug 15 AND 2 Is the universe alone?/Multiversal truths—In our second brief on scientific mysteries, we ask whether the world might make more sense if other universes existed | The Economist 15 Aug 15


    ADMIN: Thanks!

  19. Jojo commented on Sep 12

    People may be interested in reading this SF trilogy. From my POV, the 1st book was good, the 2nd was interesting but the third left me scratching my head.
    The Manifold Trilogy is a series of science fiction books by Stephen Baxter. It consists of three novels and an anthology of short stories relating to the three. The three books in the trilogy are not ordered chronologically; instead, they are thematically linked stories that take place in alternate universes.

    Fermi Paradox
    Each one of the main novels deals with a possible resolution to the Fermi Paradox. The first, Time, is set in a universe that is completely devoid of intelligent life beyond that of mankind and its creations (i.e. A.I. and uplifted animals).

    The second in the series, Space, proposes the opposite: that life is endemic to the universe, and there is intelligence in nearly all possible places of the cosmos. The solution to the Fermi Paradox in this novel is that intelligent life is continually wiped out by cosmic disasters before it has time to spread too far.

    The third novel, Origin, is set in a multiverse that is a compromise between the ideals in the first two novels: that life is only on Earth, but at the same time is everywhere. This novel solves the Fermi Paradox by suggesting that intelligent life is segregated into separate parallel universes.

  20. Scott Teresi commented on Sep 12

    People often overlook the danger of exploring or communicating itself (as rd has mentioned). At least on this planet, anytime two species or cultures have met, the stronger has subjugated or annihilated the weaker.

    The idea that life isn’t out there because we see no evidence doesn’t prove convincing. Diffuse radio signals of civilizations like our own aren’t detectable further than 5 light years out. Directed, narrow-focused signals do travel a long ways, but highly advanced life may have found it’s far better to keep yourself unknown, as it’s impossible to trust every one of your potential adversaries. With the potential impossibility of traveling great distances, regardless of technological advancement, being quiet may ensure your survival.

    Why should we think there’s any life at all if we can’t see it? Life formed here on earth pretty quickly after the planet became inhabitable (admittedly that’s our only data point!). That life has always fought hard to survive through extinctions, and as long as it’s survived, it’s continued to increase in complexity, defying the law of entropy. There are 100 billion stars just in our galaxy, and maybe 10% of those have a planet hospitable to life. Intelligent life may be as likely as all the other amazing things we know exist in our universe.

  21. Expat commented on Sep 12

    I think the entire argument is flawed on basis of the assumption that we constitute intelligent life. Look at what we do to ourselves and our home and decide.
    Perhaps Agent Smith was right.

  22. Science Bitches! commented on Sep 13

    In the last 20 years, the field of exoplanets — the planets outside our solar system — has become the fastest growing branch of astronomy.

    NASA’s Kepler spacecraft alone has identified some 3,500 potential planets in a small patch of the Milky Way, and astronomers have concluded that there are roughly as many planets in the galaxy as stars, that is to say, billions. Some of them, presumably, must be like home. Happy hunting.

Posted Under