The Fermi Paradox is an observation/question by physicist Enrico Fermi: The universe is very old. Thus far we only know of one planet conducive to life (Earth), and life did indeed arise there, suggesting that wherever life can arise, it eventually will. 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 of 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 (or at least our galaxy) is essentially uninhabited, and out there for us to settle freely. The main issue here is that, as stated above, life should be everywhere. In fact, the Rare Earth hypothesis has the opposite premise to the Fermi paradox: several key factors had to take place for Earth to harbor life first, and multicellular life later. Those factors may happen elsewhere, but all of them at once? And we haven't yet fully figured out how life appeared in the first place, so the requirements may be even higher. Life may not be so simple after all.
- 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.note 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.
It is also possible that the road between a sterile rock and a space-faring civilization has filters along the way, which cut down the huge numbers the Fermi paradox takes for granted. Those can be either filters that we have crossed ourselves, or filters that are still ahead of us. A filter that we would have crossed is the one of self-awareness and creation of technology. Over five billion species existed on Earth, and a single one, us, has crossed it. A potential filter ahead of us are the limits of technology. Although technological advances are growing at a huge speed, there are some things (time travel, teleportation, faster-than-light speed) that may be forever beyond the reach of human ingenuity or the materials at our disposal.
The Fermi paradox has also been presented as one of the arguments against the Steady state theory, that states the Universe has existed forever as we know it. 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 individual discretion. 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.
Note that technically, Fermi was actually pessimistic about interstellar travel, and it isn't technically a paradox.
Works that mention or discuss the paradox:
- Ultimate Galactus Trilogy: The Ultimate Marvel universe had a massive and public alien invasion at the end of The Ultimates (2002), but Reed Richards still considered the paradox to be valid because humanity had seen a single alien species, and there should be many more. When Nick Fury informed him about Gah Lak Tus, a threat that destroys whole planets, he found the answer: humanity does not know about alien races because this Gah Lak Tus destroys them. Note, however, that humanity does know about many other alien races, but SHIELD keeps them as Classified Information, and Richards does not have clearance to know about them.
- Fantastic Four: Life Story: Reed compares the question about aliens with that of a deer asking where are the hunters. Once you find the answer, it's too late. Humanity is safe by not knowing about alien races. Note that he was in outer space he sensed Galactus for a moment, but he still was not sure of what it was, and did not mention him (although he thought about him) when discussing the paradox on TV.
- Discussed in Axiom's End and its sequel, Truth of the Divine.
- When asked about the Great Filter — a hypothetical barrier that prevents intelligent life from colonizing the galaxy — Ampersand claims that intelligence is extremely rare, and that only two planets in the known universe (Earth and the amygdalines' ancestral homeworld) have produced sapient life. The amygdalines propagandize that they are the only intelligent life there is, and Ampersand believes that they'll sterilize Earth rather than let humanity expose this axiom as false.
- In the sequel, Nikola further reveals that only a tiny portion of the Orion Arm of our galaxy has life of any kind; the rest of the galaxy, and the entirety of Andromeda and the Local Group, are completely sterile. Humans and amygdalines are the only sapient species within this bubble of life-supporting planets, and while life could exist elsewhere in some hypothetical distant galaxy, the rate of the universe's expansion means that neither species has any hope of encountering it without developing Faster-Than-Light Travel.
- 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 Three-Body Problem trilogy offers a rather cynical answer to the paradox: due to the extreme difficulty of communicating across the gulf of space, the relative ease of Star Killing, and the need for as much resources as you can get in the face of the Universe's inevitable heat death, alien civilizations invariably annihilate one another upon detection out of paranoia and competition. The main character compares the universe to a dark forest full of hunters: anyone with a sense of self-preservation cannot risk exposing themselves without being immediately shot on sight by the hunters lurking nearby. Likewise, however noble your own intentions, you can't risk not firing at another hunter for fear of that hunter discovering and coming after you sometime in the future.
Luo Ji: In this forest, hell is other people.
- "The Fermi Paradox is Our Business Model" is the name of a short story by Charlie Jane Anders. Precursors seed the galaxy with life, then wait in cryogenic sleep while the created species gains sentience, mines their world for metals and radioactive material, then kill themselves off, so they can come in after the radiation has died down and salvage all the minerals they've dug up. They're rather embarressed when humanity remains alive long enough to make First Contact.
- 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.
- This is brought up by one of the inhabitants of a failed Tau Ceti colony in Kim Stanley Robinson's Aurora. His answer is that intelligent life, truly intelligent life, would have no interest in interstellar expansion having recognized the extreme dangers and difficulties such an effort entails and would be content to stay within their home star system in the environments that they were actually adapted to survive in.
- Grant D. Callin's A Lion on Tharthee lands on the "Earth is a Fishbowl", as they'd been watching Earth.
- Discussed in Ryk E. Spoor's Grand Central Arena when an alien scientist notes that none of the resident civilizations of the titular Arena have met each other through sublight means in the "normal universe", prompting a human character to Name Drop the paradox.
- The band Tub Ring has albums named Fermi Paradox and Drake's Equation.
- Dead Space resolves the paradox in the name. No advanced life has been found because... well, it's dead. Every advanced civilization has found Markers, been overwhelmed by the Necromorphs, and had their combined biomass formed into a new Brethren Moon, the largest, most intelligent form of the Necromorphs.
- Final Fantasy XIV eventually covers this with the Endwalker expansion. Every other race in the known universe was dead or dying when they were found, which sets up pretty much every main conflict in the entire game.
- One of the attacks used by the Final Boss of Kirby and the Forgotten Land, in which they fling a giant meteor made of space junk that's nearly the size of the entire screen through a dimensional rift, is called "Fermi Paradox Answer" in the Japanese guidebook. Said Final Boss is the newly completed body of a sociopathic alien conqueror, so it's fitting.
- Mass Effect has multiple alien species that have all been spacefaring for roughly 2000 years. However, for the most part they are discouraged from interfering with intelligent races that have yet to develop spaceflight. Some of them do so anyways for various reasons, but they never did it with humans for the simple reason that they never found us. The Mass Effect Galaxy relies on a network of lightspeed gateways to achieve Faster-Than-Light Travel. However a large number of these gateways, called Mass Relays, are inactive or dormant, including the only one that links Earth to the rest of the Galaxy. A devastating Bug War in the past caused the Citadel Council to make it illegal to reactivate dormant relays until extensive research has been done to determine where they go, in order to prevent a similar war form happening again. The Earth Relay in particular was not only dormant, it was covered in so much ice that for centuries humans thought it was a moon note , until the discovery of an alien technology archive on Mars showed them how to reactivate it.
- The other reason is that every 50,000 years or so, an unimaginably ancient and powerful machine race called the Reapers, marches in and exterminates all spacefaring species across the Galaxy. In addition, after every cycle of extermination, the Reapers make sure to erase any evidence of themselves along with most archaeological remnants of the races they just wiped out. Only leaving enough evidence for the next cycle to know that there were others before them who mysteriously vanished.
- Prey (2017) namechecks the Fermi Paradox, and offers an existentially terrifying resolution: no intelligent life has yet been encountered because the Typhon species evolved to detect and consume all advanced consciousness they come into contact with. Rather than flesh, they eat minds.
- 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. In the end, the answer to the paradox seems to be "some wiped themselves out, others went on wiping out rampages before dying off, and a whole load of them just fled the galactic disc and hid from all sight because they were terrified of the idea of the other two coming by".
- Floraverse: The prologue, which at first seems to be completely unrelated to the rest of the comic, involves a civilization discovering how they are completely alone in their universe. As such, some of them have the idea that other universes may have life, and build a device to transport them there. But right as they are about to activate it for the first time, an Eldritch Abomination appears, telling them they have mastered everything in their universe, and that they may undergo total extinction to know the final secret. They accept.
- 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!
- In The Inexplicable Adventures of Bob, Earth is located in the middle of a star-spanning alien empire, and has been since before humanity evolved, but they hide themselves from us because Earth is a nature preserve and humans are wildlife that shouldn't be disturbed.
- Saturday Morning Breakfast Cereal
Human: "Honestly it doesn't seem to bad."God: "I keep making it worse and you things keep adjusting!"
- The strip "Monkey" has an alien explain that aliens are not showing themselves to humans because humans are considered unstable and dangerous.
- "Fermi Paradox" has God explaining that it's because this world is hell (for whole sapient species, apparently) and humanity is the only species to have destroyed itself and gone there yet.
- Prime answers this in the worst way possible. Humanity sending out prime numbers, which are useful for code-breaking, is viewed as the galactic equivalent of giving your hotel room key to everyone you meet. The aliens that point this out showed up just to call humanity skanks.
- 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 other race hasn't destroyed themselves quite yet, but they're definitely affected and they haven't got out of the Stone Age).
- Starsnatcher: A Discussed Trope through a lot of the story. Becomes a plot point near the end. The reason why the Great Filter exists is that all advanced civilizations eventually get wiped out by a bunch of Sufficiently Advanced Aliens referred to as "They". The reason why "They" do this is that they are a Type III civilization who need all of the Milky Way's resources to prosper. They refuse to let another civilization rise to their level and compete for resources with them. Thus, if a civilization becomes advanced enough to attempt interstellar travel, they'll inevitably run into death traps "They" created.
- SCP Foundation:
- This is a central theme in the Spanish-speaking canon Observando Estrellas Muertas note .
- SCP-3426 is another discussion of the Fermi Paradox, stating that the reason we don't see any aliens is because of a naturally-occurring phenomenon where all planets whose civilizations become sufficiently advanced are killed by reality breaking down at their exact positions. The part about it being natural is a lie. It's heavily implied that it's the doing of the Pattern Screamers, sentient masses of nothingness, who warp reality to conquer these planets and add them to an ever-growing intergalactic empire. Their agents may have already descended to Earth to plot its downfall, as evidenced by several other SCPs confirmed to be part of their kind in some form.
- Isaac Arthur has a whole series of videos discussing various plausible reasons why we don't see signs of alien civilizations going out and building a Dyson Sphere around every star in the galaxy.
- George Carlin half-jokingly suggested that we haven't discovered aliens because they know exactly how bad we are as a species and are actively avoiding us.
- Calvin and Hobbes suggested the same thing:
Calvin: I think the surest sign of intelligent life in the universe is that none of it has ever tried to contact us.
- As did Eric Idle's "Galaxy Song" Monty Python's The Meaning of Life'''
And pray that there's intelligent life somewhere up in space...
...'cos there's bugger-all down here on Earth