Useful Notes / Fermi Paradox

Arthur C. Clarke

The Fermi Paradox is an observation/question by physicist Enrico Fermi: The universe is very old. Life (from a scientific viewpoint) seems to be relatively simple—simple enough that, given the unimaginable size of the universe, there should be millions of planets with life scattered out there, and surely thousands at least in our own galaxy. And even without Faster-than-Light Travel, an intelligent spacefaring species should be able to spread across the galaxy in a relatively short amount of time.

So where is everybody?

We should be able to see all kinds of signs for intelligent alien life when we look at the stars, or possibly even evidence of alien life visiting Earth. But we don't.

There are numerous proposed solutions to this question, which break down into two broad categories:

  • Absent Aliens is the simple solution, and makes for a fairly straightforward story: the entire universe is essentially uninhabited, and out there for us to settle freely.

  • Invisible Aliens is more tricky, as there may be all kinds of reasons we might not see the aliens that are out there. Even if life is common, intelligent life might be rare for any of a number of reasons. And even if intelligent life is common, it might be hiding, or it might not last very long. If they're bizarre Starfish Aliens, we may simply not recognize what we're looking at. If they're Sufficiently Advanced Aliens, we may not even have discovered the technologies required to detect them. And if they're more than sufficiently advanced, their intelligence might have led to some sort of transcendence that we can't detect, even in theory. Alternatively, they may be perfectly visible already, but The Men in Black are making sure the general public doesn't realize it.

The Fermi paradox has also been presented as one of the arguments against the Steady state theory, that states the Universe has existed forever. With an infinite amount of time behind it — no matter how rare truly advanced space-faring species were — sooner or later, not one but many would appear and we'd see evidence of their existence.

Related to the paradox is the Drake equation, one attempt to quantify the elements required to actually discover other intelligent life forms out there. The Drake Equation has been criticized because most of its terms are unknown, leaving it to the discretion of individuals. Depending on the numbers you put in, the number of intelligent species per-galaxy as predicted by the Drake Equation can be anywhere from millions to less than one. In the end, these terms can never be known for sure until after we resolve the Fermi Paradox one way or the other: either by finally contacting an alien civilization, or by exploring enough of the universe to say convincingly that they don't exist.

The Other Wiki has more details.

Note that technically, Fermi was actually pessimistic about interstellar travel, and it isn't a paradox.

Works that mention or discuss the paradox:

    open/close all folders 

    Comic Books 

  • Stephen Baxter's three Manifold novels investigate three different solutions (using the same characters in each novel):
  • A favorite subject of David Brin's:
    • Xenology: The Science of Asking Who's Out There is an essay on the subject.
    • Existence discusses the paradox at length, especially in the chapter headers.
    • He has mentioned that it was part of the inspiration for the Uplift series. Where every space-faring race is governed by a bureaucracy that tightly controls colonization rights and which declared Earth's sector off-limits millions of years ago.
  • "The Fermi Paradox is Our Business Model" is the name of a short story by Charlie Jane Anders.
  • Discussed by an astronomer and a possible answer provided in Variable Star. As a Generation Ship leaves Earth, the astronomer on the ship sees something odd about the sun. A quarter of the way through their trip, the sun explodes, destroying the entire solar system. The inhabitants of the ship conclude that this was done on purpose by an alien race, resolving the paradox Abusive Precursors style.
  • More Information Than You Require proposes a solution: that the aliens are merely very far away. Possibly even... on other planets. It's also implied that Fermi himself was an alien.
  • Alastair Reynolds' Revelation Space universe at first appears to be a case of Absent Aliens as humanity finds many worlds with life, and the ruins and relics of numerous advanced interstellar civilizations, but only a few rarely encountered, sparsely distributed interstellar species. As the series progresses, however, it turns out there's a very good reason for this...
  • In Charles Stross's A Colder War short story, some characters discuss the fact that they're pretty sure they've solved why the paradox exists. It's not very pleasant.

  • The band Tub Ring has albums named Fermi Paradox and Drake's Equation.

    Video Games 
  • Mass Effect Zig zags this. An Eldritch Abomination species called the Reapers eliminates all spacefaring species once every 50,000 years but with the space transportation technology available, any number of species humanity does encounter could have visited us prior to our space age. In fact they did visit a pre-space age species and give them space travel so that they could help in a war, which led to disastrous results. So the reason we aren't visited is a combination of implied Alien Non-Interference Clausenote  and Eldritch Abomination. The uplifitng of other races has occurred before the present time as seen with the Prometheans uplifitng the Asari and the Hanar, who themselves saved the Drell from total extinction at the cost of having a lot of their people left on their dying homeworld.

    Web Animation 

    Web Comics 
  • In A Miracle of Science Mars re-established contact with the rest of humanity after going out into the universe and finding no aliens, they were all dead.
  • One strip of xkcd suggests that the solution to the paradox is that fun trumps survival.
    • Another offers an alternative solution, they're all hiding
  • The paradox is brought up in Schlock Mercenary as a concept that has been largely disregarded in the thousand years since First Contact, but, after hearing evidence that galaxy-spanning civilizations have risen and fallen many times over millions of years the idea is revisited.
  • The paradox is lampooned in Free Fall: an alien squid (Sqid, if you would) who just so happens to be very tasty to virtually any sort of Terran animal points out that humanity's resilience is, in large part, due to asteroids smacking into Earth and giving more time to evolve: those who got it on the first try have simpler cellular structures. So...
    Sam: There is no Fermi Paradox! Every time the aliens make it to Earth, the cows get them!

    Web Original 
  • In Veil of Madness, the reason humanity hasn't found any aliens is because Earth is smack in the middle of the titular "Veil of Madness", which causes violent insanity in any intelligent life that lives there, usually driving them to extinction. Humanity is the only race to have avoided this (well, one race hasn't destroyed themselves quite yet, but they're definitely affected and they haven't got out of the stone age).