Where Are All The Aliens? What Is Fermi’s Paradox?

Where Are All The Aliens? What Is Fermi’s Paradox?

- in Weird
What is the fermi paradox?

At some point in our lives, we gaze up at the night sky and wonder if we are all alone in the universe. With trillions and trillions of stars up there, most with very their own solar systems, one would think that there is virtually an unlimited number of chances for the spark of life to kick off. We don’t even have to look to the stars to wonder if life originated on another world, we can look in our very own backyard — Mars and Jupiter’s moon Europa both offer a tantalizing chance (albeit a small one) of microbial life flourishing.

Given the sheer vastness of our universe, it seems impossible that we’re all alone out here. The odds of life “finding a way” has to be a sure thing, right? If that’s the case, then where are all the aliens? Why haven’t we seen any evidence of them? That’s the question that lies directly at the heart of Fermi’s Paradox. However, before we can dive into that, we need to know a bit about the Drake equation.

What Is The Drake Equation?

The Drake equation is a mathematical equation which attempts to predict the amount of intelligent civilizations that should exist in our Milky Way galaxy. This is what it looks like:

N = R*fp*ne*fl*fi*fc*L

This can look awfully confusing. Fortunately, it’s actually much simpler than it looks. We’ll break it down for you:

  • R = The rate of star formation
  • Fp = The percentage of stars that have planets
  • Ne = The percentage of those planets that can support life
  • Fl = The small percentage of those planets that actually go on to develop life
  • Fi = The even smaller percentage of planets with life that actually go on to develop intelligent life (i.e, humans)
  • Fc = The percentage of those that develop technology that allows for detection (e.g, radio signals)
  • L = Length of time that such civilizations release those detectable signals

and finally,

  • N = the number of civilizations in our galaxy with which communication might be possible

So, if you multiply all that together, it should give you an extremely rough approximation of how many civilizations there are out there. When we plug the numbers into the equation, conservative estimates put the total number of civilizations around 1,000 while more liberal estimates are as high as 100,000,000. That’s right, there could be up to 100 million civilizations just in our Milky Way galaxy.

So what gives? With numbers that high, our Milky way galaxy should be teeming with alien culture, right? Where are all the aliens?

The Fermi Paradox

While working at the Los Alamos National Laboratory in the 50s, a physicist by the name of Enrico Fermi was on his way to lunch with his coworkers. While they walked, he and his coworkers facetiously discussed the recent UFO sightings that had made the local newspaper that day. Dismissing the reports, Fermi offhandedly asked, “Where is everybody?” (referring to aliens).Von Neumann machine While he and his coworkers sat and had lunch, the conversation continued but became a bit more serious. Eventually Fermi got serious enough to begin writing down mathematical equations to try and figure out what the actual odds and percentages were.

He knew that even if an alien civilization just sent out tiny robotic probes to traverse the entire Milky way galaxy instead of going themselves (Von Neumann machines), it would only take on the order of millions of years to spread out over the entire galaxy. However, billions of years have passed since the universe sprang into existence, and in that time there have been no aliens, no robotic probes, or any other evidence of any kind — just a deafening silence. We’ve seen no indication that even a single alien civilization exists.

This likelihood of alien civilizations existing contradicts the fact that we’ve yet to see any evidence of them. It’s paradoxical – and that’s Fermi’s Paradox.

Is Something Wrong With Fermi’s Paradox?

We believe so. The problem with the Fermi Paradox is that it’s not really paradoxical at all. The paradox presumes we should have had contact with aliens by now but that is an inaccurate presumption. There are quite a few key factors which work against his presumption of contact. The most obvious of which is:


inverse square law

The distances between stars are so vast, it is difficult for our minds to comprehend. Not just for physical travel but for sending radio signals too. We actually go into great detail about this very point in our article titled, “How Far Have Our Radio Signals Traveled From Earth?” There, we discuss the effect of the inverse square law on radio signals.

Would it be possible for someone to detect the tiny ripple of a pebble dropped into the Pacific ocean off the coast of California while standing on a beach in Japan? That would actually be easier to accomplish than trying to listen in to an alien civilization’s radio/TV broadcasts at these distances. The inverse square law (a form of signal degradation) makes all of our own radio and television broadcasts indistinguishable from background noise at only a couple of light years away from the Earth. Unfortunately, movies like Contact have it wrong; aliens will not be tuning in to catch the latest episode of The Big Bang Theory. Our terrestrial TV, radio and satellite broadcasts just aren’t sent with enough juice to counter the effects of the inverse square law.


Fermi Paradox comic XKCD

As humanity and society continues to evolve, so does our technology. And as our technology evolves, so does our energy efficiency. Whether it’s CPUs using less watts of energy to do more calculations faster, or more fuel efficient cars, light bulbs, or refrigerators, energy efficiency goes hand in hand with our own technological advancements. Things would be no different for an advanced alien civilization. In fact, we should expect them to be inherently efficient. With this in mind, we believe it would be foolish to believe an advanced alien civilization would use as something as inefficient as radio signals to communicate. And if aliens aren’t using radio signals to communicate, then despite the best efforts by organizations like SETI, we haven’t even been listening.

They may be attempting to communicate with us (or anyone else who will listen) right this minute but we cannot hear them because we do not yet possess the technology to listen. An analogy of this situation is if you were at your local park and decided to use smoke signals in an attempt to communicate with other humans. Would you conclude there were no humans on earth if you didn’t get a response back? To extraterrestrial civilizations, radio signals may be very primitive because of how inefficient they are at carrying data and how much power is required to send a coherent signal across those vast distances.

The comic pictured above perfectly illustrates these points.


Another possibility for a lack of contact is time. While billions of years have passed since the big bang, it may have been only recently that things have calmed and settled down enough for life to evolve to this point. The early universe was an extremely chaotic & violent place, with all kinds of terrifying events happening regularly.Gamma ray burst destroying earth What we call “extinction level events” might have been much, much more common. Life may get started only to get wiped out again by an asteroid impact, from the explosion of an extremely short lived first generation star, or from a gamma ray burst. Gamma ray bursts, beams of highly energized particles emitted by an exploding star, were much more common in the early universe. Any planet caught in the path of one would have its complex life wiped out, and needing to start over from scratch (see our article, “Top 10 Ways The Universe Could Kill Us All“).

In fact, the Earth has experienced at least 5 of these extinction level events already and more may happen in our future. Thankfully there are no stars currently in range capable of releasing a gamma ray burst, but that could change in the distant future. If a passing star within ~100 light years went supernova, and it was on an axis where its poles were pointed at the Earth, the GBR would be enough to obliterate our ozone layer. If a much larger star passed nearby, one capable of going hypernova, the GBR from the star hitting Earth’s atmosphere would be the equivalent of one kiloton of TNT per km² over the entire hemisphere facing the star. Our entire atmosphere would be cooked off within moments. Any life on the surface would experience radiation ten times the lethal dose. Most complex life would simply vanish. The scary part is that GBRs move at the speed of light which means there would be no warning or heads up that such an event was going to occur.

The Great Filter

Another possibility is something called the Great Filter hypothesis. The idea was put forth by economist Robin Hanson in 1996 in an online essay and has since received quite a bit of recognition and attention with regards to Fermi’s paradox. In his essay, he describes the following nine steps as an “evolutionary path” that results in the colonization of the galaxy:

  1. – The right location (a star system with habitable planets & the “stuff” required for life)
  2. – Reproductive molecules (e.g., DNA)
  3. – Simple single-cell life
  4. – Complex single-cell life
  5. – Non-Asexual reproduction
  6. – Multi-cellular/complex life
  7. – Tool-using animals with large brains (early proto-humans)
  8. – A technology driven modern society (this is where we are)
  9. – Colonization explosion (colonizing other worlds & star systems)

The great filter hypothesizes that at least one of these steps is highly improbable. Due to the unlikelihood of overcoming it, it is believed to act as a roadblock to the evolution and progression of intelligent life.

If Hansen’s great filter hypothesis is on the right track, that must mean one of the following options described in the graphic below are true.

The Great Filter - Fermi's Paradox

One thing you may have noticed is that we don’t touch on what a “type 3 civilization” is. Don’t worry, we plan to talk about that in a fascinating article in the very near future. If you simply cannot wait, please refer to the references and citations at the bottom of this article, specifically the one which references Nikolai Kardashev and his “Kardashev scale”.

Other Reasons For Lack Of Contact

There are plenty of other reasons for a lack of contact, some of these reasons tend to fall on the side of common sense, while others are pretty fantastical and “far out there”. We’ll take a look at some of these reasons and go into a bit of detail for each. If there are some big glaring reasons you think we may have missed, feel free to drop us a comment below and let us know.

— Living In a Matrix Or Simulated Reality —

Living in a computer programThis one is, admittedly, a pretty wacky idea with zero corroborating evidence to back it up. Nonetheless, it’s an interesting thought experiment and it tickles the mind so we’ve decided to include it. The hypothesis claims that human civilization is living in a matrix-esque reality. That is, the reality we live in is a computer simulation or program and that our behavior, interactions and our entire reality relies on whatever rules or conditions were laid out by the programmer. If the mastermind behind this simulated reality wants us to meet aliens, then we’ll meet aliens. If they want us to be the only life in the entire universe, then that’s the reality in which we exist. The programmer would effectively be a god.

As for reasons why something or someone would be running such a computer program, it could be a game, a test or some sort of experiment. It could even be a simple proof of concept. The scary part is wondering what happens when someone pulls the plug.

— Intelligent life Invariably Leads To Self-Destruction —

Nuclear War - Self-destructionThis reason postulates that before intelligent life can colonize other planets and star systems, it inevitably destroys itself. Methods include biological warfare which decimates most of the planet’s population, nuclear war, environmental disasters including artificially induced climate change or using up all the planets’ natural resources without viable alternatives. All it takes is one bad actor within a civilization with enough power to cause the extinction of a species and it is game over.

Such an event has nearly occurred multiple times here within our own civilization. During the 60s, we had the Cuban missile crisis which had the world on the brink of nuclear war. Nuclear war doesn’t have to be intentionally kicked off either – it can happen by accident as we go into more detail in one of our previous articles (“Did Stanislav Petrov Really Save The World?“). There, we talk about how a glitch in Russia’s early warning satellite system made it look like the U.S had launched a nuclear strike on Russia. If it wasn’t for Mr. Petrov’s quick thinking, we may not be here today to recount these events.

— They’re Here Already —

A few people even believe that the reason we haven’t heard from aliens yet is that they’re here already. Some of these people believe that they are either hiding and studying us, or they are already in communication with select people, organizations and/or governments. Aliens are here alreadyAs for reasons for not making their presence known; these people believe that public knowledge of extraterrestrial life would cause panic, confusion, chaos, economic instability or even anarchy among the population.

Since we do not know what “alien life” would look like because we haven’t interacted with aliens, it’s possible that they are simply so different from us that we wouldn’t recognize them, or they exist in a form that goes undetected by us – perhaps even existing as pure energy. It’s also possible that they’re so technologically superior that even if they were here, in the very same room as us, we would not notice. Arthur C. Clarke once said, “Any sufficiently advanced technology is indistinguishable from magic“. And if the advanced technology was orders of magnitude more advanced than our own, aliens would be virtually god-like to us. They might be able to manipulate matter in a way that allows them to remain invisible, unseen and unheard. Who knows, maybe they have a deep understanding of quantum mechanics and can use quantum tunneling to walk right through the thickest of walls or teleport over vast distances. If an invisible alien could use technology we can’t even begin to imagine, how would we ever hope to notice them if they don’t want to be noticed?

— Earth Is A Cosmic Zoo —

The zoo earth hypothesisAnother interesting hypothesis puts forth the idea that the Earth is part of a cosmic “zoo” or preserve. Aliens may have cordoned off our little section of the milky way to let us evolve and develop naturally. This could either be because we’re some sort of attraction, or it could have benevolent purposes as contact with aliens might spoil or have negative effects on our own technological and social development. If a civilization was advanced enough, there would be very little to gain from direct contact that they couldn’t get from observing at a distance or while hidden, while the risks of contact would be enormous — both for humans and for the alien civilization.

These first alien civilizations may have had bad experiences with previous first contact situations which may have lead them to adopting this zoo approach. They may be waiting for us to progress to a certain point in our development before revealing themselves to us. It could be very similar to Star Trek’s “Prime Directive” where nobody is allowed to contact or interfere with primitive alien civilizations until that civilization has met certain criteria (in Star Trek’s case, civilizations had to achieve or discover warp travel).

— Purposeful Isolation —

Alien SupercomputerIt is also possible that aliens have completely isolated themselves from the rest of the universe. Let us pose an interesting question: If you could become effectively immortal, living for millions, perhaps billions of years in what you consider heaven or the perfect utopia, would you do it? An advanced alien civilization may have done just that by uploading the minds of their entire civilization into a supercomputer. This supercomputer would be so advanced that it makes our current supercomputers look like an abacus. However, one of the drawbacks of transcending from the physical world to a digital virtual heaven is that you and your civilization would be isolated from the rest of the universe. Instead of exploring and colonizing the often desolate and incredibly dangerous Milky Way, they chose immortality by existing in a computer simulated utopia.

Such a civilization would be at risk and relatively defenseless so a lack of contact would be in their best interests. If another alien civilization discovered their technology and decided to “pull the plug” or steal it for themselves, their entire species would be wiped out, their utopia over with, and their immortality at an end.

Another potential reason for isolation is that they’re simply afraid. They know the universe can be a hostile place and would rather not take on the risk of contacting unknown alien races. There might be other alien races out there that are extremely predatory, only interested in acquiring resources to feed its civilization like in the movie Independence Day. If such alien civilizations existed, it would be best to remain quiet and unnoticed.

— We’re Truly Alone —

We re all alone in the universeAnd finally, what we think is the absolute least likely reason for a lack of contact is that we’re entirely alone in this universe. We think this is the least likely reason because astronomers now believe the universe to be effectively infinite in size.

Being infinite in size means an infinite number of stars, which means an infinite number of solar systems and planets, which also means that there are infinite number of chances for life to evolve. More than that, it also means there’s an infinite number of chances for intelligent life to evolve. And since it has done so once already (humans), we believe that this is one of the least likely reasons. It’s simple mathematics.

And as a coincidental segue into our very next article which will be released shortly, if there’s an infinite number of chances for life to evolve, wouldn’t that mean there’s a very real possibility that life could have evolved in exactly the same way as life evolved on earth? Perhaps even giving rise to a mirror/alternate version of humans? Stay tuned for our next article where we tackle the multiverse, if there’s any science behind it, and what it means (if anything) to the science community.

Jones, E. M. (March 1, 1985). “Where is everybody?” An account of Fermi’s question” (PDF). Los Alamos National Laboratory. OSTI 785733
Nicolas Glade, Pascal Ballet, Olivier Bastien. (2012) “A Stochastic Process Approach of the Drake Equation Parameter” (PDF) arXiv:1112.1506
James S. Trefil, Rood, Robert T. (1981). Are We Alone? The Possibility of Extraterrestrial Civilizations. New York: Scribner. ISBN 0684178427.
Vukotic B., Cirkovic MM (2008) “Astrobiological phase transition: towards resolution of Fermi’s paradox.” Orig Life Evol Biosph. 2008 Dec;38(6):535-47. doi: 10.1007/s11084-008-9149-y.
Kardashev, Nikolai. “On the Inevitability and the Possible Structures of Supercivilizations” June 18–21, 1984 Reidel Publishing Co., 1985, p. 497–504.
Ellis, John; Schramm, David N. (March 1993). “Could a nearby supernova explosion have caused a mass extinction?” arXiv:hep-ph/9303206
Hanson, Robin (1998). “The Great Filter — Are We Almost Past It?
Ball, John A. (Jul 1973). “The Zoo Hypothesis.” Icarus 19 (3): 346–351.


  1. A few others:

    – We may need a large moon for complex life because it stabilizes its planet’s axial tilt.

    – We may need a Jupiter for complex life because it sweeps up impactors and stabilizes the orbits of the rest of the Solar System.

    – There may be a Galactic Habitable Zone. Outside it, there’s not enough material to build rocky planets. Inside, it’s too violent.

    – A planet may need a moon for space-faring societies to evolve. Without a nearby, accessible moon, the jump to other planets might be too large to be of interest.

    – A planet may need a Mars nearby to provide an accessible later goal. We’d be a lot less interested in going beyond the Moon if the only alternative was something like Venus or Mercury.

    – A society with advanced virtual reality may decide it can have all the adventure it wants inside the VR.

    – A planet with a machine utopia may degenerate into passivity. Eloi with benevolent cyber-Morlocks.

  2. What about the percentage of civilization that destroy themselves through war or using up all of their resources?

    1. That should qualify as a “Great Filter” — in fact, I’d say the Nuclear Holocaust category should be in that Great Filter category and not in the “Other” category.

  3. I haven’t seen anyone write on this topic and include the “extreme alien” scenario. Similar to the technology argument and especially to the ant cartoon from Xkcd, what if aliens are so “alien” that they are completely unrecognizable to us? For example a species that for some reason uses base 100 or base 5 math rather than base 10 might not recognize our messages as anything other than background noise, and likewise we would filter their messages out as background noise as well due to the related equations being either too complex or too simple to be viewed as ordered messages.

    Likewise non bipedal species are much more likely than bipedal ones. How does a non-biped think? Perhaps they have forgone technology all together, or their tech is so foreign that we cannot detect each other.

    This also can go along with the “They are already here” theory. Dolphins, grasshoppers, whatever, could in theory be alien life. While that’s not likely it is possible (and would explain Australia) and we may have no way of really communicating with alien species if and when we do find them. With no common point of reference (numbers, letters, common shapes, etc.) we cannot begin to communicate. An alien species could in theory have no concept of the number 10, of a mountain, of an ocean. That would make communication difficult to almost impossible. Then again maybe they also just have no interest in communication with us to begin with.

  4. What if we are the aliens of some past planet? My mom believed we were once on another planet that was destroyed, and the inhabitants of that other world came here and helped populate the Earth with life.

  5. It seems that the drake equation assumes a constant rate of star formation, which I believe is an error. For example there was probably a higher rate of star formation in the universe’s infancy. So the universe would have created a lot of stars and planets early on and less now, so the drake equation would perhaps return lower than realistic results. Another issues is that the rate of star formation seems a lot less relevant of a factor than the approximate total number of planets in the milky way.

  6. What if the alien life is just like us; looking for life on other worlds, yet don’t have the technology available to actually search yet? They could be in the exact same position as us, coming up with theories for answers to questions like “Are we alone in the universe?”, “Where is everyone?” and “If there is life out there, why haven’t they contacted us?” the answer could be as simple as “They haven’t developed the technology for inter-planetary travel.” would it be that hard or impossible for that to be the case?

  7. A few of the commentators here have actually got the answer. We have not found aliens because we are all looking in the wrong place. First, it is not necessary that aliens need not necessarily be:

    1) Anthropomorphic or even resemble anything close to something we’ve seen or heard of. They can be completely-energy based or worse formless, let’s say ameboid.

    2) They have NO INTEREST in us because we are so primitive to them and serve no interest. Think of yourself as an alien and you’re exploring the galaxy. Will you look for a planet filled with humans or a planet filled with cockroaches? Most probably the former because cockroaches serve no value to you. Now, replace the word “human” with alien and “cockroach” with the word human, you get the picture!

    3) They may already be here and most probably looking at us with amusement on how such a primitive race considers itself civilized and wages wars constantly, destroys its forests in the name of development and abuses technology.

    4) People believe that Aliens may be friendly or hostile. But I don;t think this is the case, I think they’re rather indifferent or disinterested in us or else we would have had a hundred thousand visits already.

    5) I am laughing at the fact on the “technology part”. For us technology means electronics, but what if the aliens are so superior in intellect that they don’t need a medium “say computers or robots” to do their jobs. What if they have trained their minds to such an extent that they can make/break matter?

    6) What if they are simply hiding themselves and are just watching us to see if we will ever reach their level?

    7) Finally, what if they are actually hiding in plain sight — let’s say on the Moon, Mercury, or even Mars and we just cannot identify them as the human eye is trained to look for life only in the most possible of places (which contain water/oxygen/carbon). What if aliens are fire-based/metal-based life, ameboid in shape and moving around being mistaken as space debris?

    8) What if our World is not what it seems and we are the proverbial Golden fish in the bowl which cannot never see the truth outside the bowl?

  8. I think too many people see every non-human thing
s alien
 & nature has [during its evolution] learned that such feelings of separateness can lead to very destructive behavior, 

    SO it had to put great distances between its habitable worlds
. If there are ‘aliens’ in our galaxy, they’re probably living in whichever spiral arm is furthest from (or opposite) our own.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may also like

Does A Diamond Really Last Forever?

You’ve probably heard the phrase on television, seen