The Fermi Paradox: Are We All Alone?

Tony Rowell

Oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. 

These are the elements necessary to create life as we know it. In a prehistoric soup on a rocky and volcanic Earth, battered by solar flares and thundering asteroids, a supremely unlikely dance between these elements took place. A delicate coincidence of heat, ions, turbulence, and electricity tipped over the first domino in a row 4 billion years long that would eventually lead to hollow-boned pterodactyls flying through the sky, seals spinning beach balls on their noses, and you, reading this article. 

Since that primordial encounter 4 billion years ago, life has continued in one direction: growth. Life exists at the tip of the tallest pine trees, in the frigid water beneath the Arctic ice sheet, between the cracked desert earth baked by the drying sun. There’s only one other place left to go, and that’s outward. Outward into space. 

With the billions of stars in our galaxy, and trillions of galaxies in our universe, it’s hard to imagine that some version of this life-creating reaction hasn’t happened on another planet at least once, if not thousands of times, and that at least one of these alien species hasn’t followed that life-affirming instinct to spread and explore outward. After all, they’ve had nearly 15 billion years to do so. So why haven’t we encountered any aliens?

The Fermi Paradox asks this question, pointing out that despite the universe’s age, vastness and complexity, we still have not seen any substantial evidence of extraterrestrial life. Named after physicist Enrico Fermi, the paradox allegedly came to be in 1950 during a lunch with colleagues when, while discussing the likelihood of alien life, Fermi asked suddenly, “so where is everybody?” 

Since that discussion, many solutions to the paradox have been hypothesized. They consider elements like the possible social and economic structures of alien civilizations, the rarity of life itself, the nature of suns and planets and asteroids, the gaps in our scientific understanding of the universe, and countless other factors.

While anyone can theorize on why we haven’t made contact with alien life, legitimate solutions to the Fermi paradox should: 

1) Not assume that Earth is in a privileged position in the universe

2) Be logically sound

3) Be applicable to all alien civilizations (not one specific type, with one specific motive)

4) Have support from natural and social sciences 

5) Avoid anthropocentrism, i.e. not make assumptions about alien species based on humanity 

Keeping these criteria in mind, here are a few solutions to the Fermi Paradox that might explain why we appear to be alone in the universe. 

Zoo Hypothesis

Any discussion of the Fermi Paradox would be incomplete without mention of the zoo hypothesis. The basic principle is that aliens are able to contact us, but are unwilling to do so, instead treating us like zoo animals, observing but not interfering directly. This is one of the more widely-known solutions to the Fermi Paradox, and it’s easy to understand its popularity. If intelligent ants can farm aphids, and intelligent humans can keep tigers as entertainment, why couldn’t an intelligent alien species do the same to us? 

Theories of this nature range widely; they could be remotely monitoring us from far away, through a telescope planted on our solar system’s asteroid belt expertly hidden from view. They could be moving about our planet in stealth, collecting data on our development as a planetary ecosystem. It’s recognizable in the Star Trek franchise, where their Prime Directive is to monitor, but not interfere with, civilizations that haven’t yet achieved interstellar travel. On the more extreme end, theorists say our entire conception of our world and universe could be artificially created, and we exist in a bubble constructed by an alien race, nothing more than a lab experiment that could be discarded at any moment if the results are unsatisfactory. 

Despite how compelling this theory is, it is blatantly unscientific. It assumes that Earth is unique in relation to other planets in the universe, chosen specifically to be monitored. It imposes anthropocentric traits onto alien species, like the desire to conserve, observe, and experiment on other beings. Besides the principle of the Fermi Paradox itself, that we have not yet contacted alien species, it has no scientific grounding. 

Rather than being a legitimate solution to the paradox, the Zoo Hypothesis serves as more of a reflection of humanity. It’s nice to think that our species has been chosen by a more intelligent being for observation, that we are as special as we think ourselves to be. We wonder what they would think of us as a group, what they would think of us as individuals, what they think we should do. We wonder if they’re rooting for our survival or destruction. And we wonder how, without benevolent alien intervention, that possible destruction might play out. 

The Inevitability of Self-Destruction

In the past few decades, it seems like humanity has been teetering on a see-saw of total annihilation, bouncing between hope and horror, progression and regression. We seem entirely capable of destroying ourselves, whether through nuclear war, ecological degradation, or pandemics, yet it hasn’t happened just yet. But what if this isn’t unique to us – what if is it the nature of intelligent life to destroy itself?

The grounding behind this theory is that the technological capacity for self-destruction grows faster than the political capacity to control it. In other words, we’re much better at creating destructive technology than learning how to use it responsibly, and this could have disastrous consequences once a species reaches a certain stage in its social and technological progress. 

While this theory is based on the only species we can observe, humans, its logic doesn’t necessarily rely on anthropogenic traits. Assuming the most basic level of intelligence in an alien species – that they’re able to communicate between themselves and thus build on their previous scientific discoveries – their technology, like ours, would become more and more advanced over shorter and shorter intervals of time. Look at how quickly the internet was invented after computers were, or how the cost of sequencing a genome has gone from $100 million in 2001 to around $1,000 today. Our own technological advances are catching up to us, and as they begin to surpass the limits of our control, it’s important to remember that every tool is double-sided. 

After all, a species that can make a knife to hunt for food has also made a knife to stab its brother. A species that can make a rocket go to the moon can also make a rocket launch a nuclear attack. And a species that can vastly improve its quality of life by making gas-powered cars and coal-powered electricity can also destroy its planet with those very things. 

Technological growth enables more technological growth. This is a simple, logical fact. Then, the only thing standing in the way of the inevitable destruction of any society is that society’s ability to cope with that growth faster than it takes them over. It is entirely possible that no living organisms in our universe, or at least within the short 10,000-year timeframe of our civilization, have been able to surpass that challenge. Our universe may be filled with wasted planets of civilizations long past that never traveled a few light-years away from home before succumbing to the weight of their own existence. And we may be reaching that point ourselves. 

Rare Earth

Before a species can get to the point of self-destruction, it needs to harbor the conditions for life in the first place. The chance occurrence of living organisms requires countless different factors to be in just the right place at just the right time. In discussions of the Fermi Paradox, these are known as the Great Filters, and any life form that doesn’t get past them has no hope of contacting us on Earth. 

The closest habitable planet to Earth, Proxima b, is just four light-years away. It’s about the same size as us, and about the same distance from its sun, Proxima Centauri – it was our best hope of finding anything remotely habitable within a reasonable distance from Earth. 

On May 1st, 2019, the Hubble Space Telescope detected a solar flare from Proxima Centauri. The star’s brightness factor increased by 14,000, washing Proxima b in a tidal wave of deadly radiation and likely stripping the planet of its atmosphere. Any life in the star’s habitable zone would have been extinguished immediately. This wasn’t terribly devastating, though, as scientists recently discovered that Proxima b is also regularly pummeled by asteroids that sterilize the planet. Despite being in its sun’s habitable zone, the planet is undoubtedly unfit for the development of life as we know it. 

Unrelenting battering by solar flares and asteroids isn’t unique to this solar system; in fact, this is the norm for most exoplanets we’ve discovered. Earthlings enjoy unusual levels of planetary stability. The closest asteroid to come near our planet this year was 1.25 million miles away. The most prominent solar event we’ve ever recorded is the Carrington Event, a geomagnetic storm that wiped out all electronic communications in 1859. While a great inconvenience, it doesn’t come nearly as close as the lethal flares or earth-shaking asteroids that regularly blast Proxima Centauri’s planets. 

Needless to say, the rarity of such stability lends to another solution to the Fermi Paradox; that hospitable planets are just a lot less common than we think. Despite the quintillions of planets out there, there still exists the possibility that Earth is truly the first planet that’s had the conditions to develop complex and intelligent life forms. The ancient alien civilizations people imagine when they think of the Zoo Hypothesis, or dream of a real-life Star Trek fleet, could be us in just a few millennia. But for now, we may very well be all alone. 

The Phosphorus Problem 

It’s one thing to have a stable planet uninterrupted by bursts of radiation or speeding chunks of icy rock. It’s another to have all the right ingredients in place for the primordial soup that will one day become a species that sprinkles salt and pepper on sliced tomatoes or scrolls mindlessly through TikTok for hours at a time. The backbone of these activities, and all life on Earth, is phosphorus. 

These phosphorus backbones are more than figurative. DNA and RNA, the essential building blocks of life, are held together by sugar-phosphate backbones. The element helps power all living organisms through the phosphate group ATP (adenosine triphosphate) as energy is transferred and released through its conversion to ADP (adenosine diphosphate) and back. This process is used by literally every living being, plant and animal alike. 

Phosphorus isn’t the only element required for life; those were listed at the beginning of this article. But its rarity puts it in position as another Great Filter. While the rest of the necessary ingredients are relatively abundant, phosphorus is scarce. Our body mass is 1% phosphorus, but it makes up only 0.1% of the mass of the Earth’s crust, and gets rarer as you travel further from our planet (it’s 0.0007% of our solar system’s mass). Scientists postulate that our relatively high abundance of the element came from phosphorus-rich asteroids colliding with Earth when it was still in its infancy, later assimilating into the Earth’s crust. Even a slightly lower concentration of phosphorus on our planet would drastically alter the already-low likelihood of life occurring. 

Like all natural elements, phosphorus is created in stars. This means that the younger a planet is (like ours), the longer the rest of the universe has been around, and the more supernovae have occurred to send phosphorus into space to eventually hitch a ride on an asteroid and collide with an infant Earth. There is more phosphorus in the universe now than there was a few millennia ago, and much more than there was 10 billion years ago; the likelihood of life as we know it forming only increases as time goes on. On the flip side, the likelihood of life as we know it having been formed is lower now than it will ever be. We might be the first planet to have the right amount of phosphorus, the right balance of conditions for it to form into some version of RNA and DNA. We might just have to wait a few million more years, for a few million more supernovae, to meet our neighbors in space.

Life As We Know It

Oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. These are the ingredients that make up life as we know it. 

This brings us to our last explanation of the Fermi paradox; alien life may not be life as we know it. Aliens may be too alien for us to understand; we may be looking for the wrong thing entirely. While cinematic interpretations of aliens have evolved far from the embarrassingly anthropocentric little green men from a few decades ago, we are still looking for habitability based on our human standards for survival. We are still looking for signals using our own methods of communication, and we are still looking for beings that operate according to our known laws of physics and thermodynamics. 

Oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. That’s what we need to make living beings, intelligent beings that might one day make apple pie or kiss their children on the cheek or launch themselves in a rocket and plant a flag on the Moon. One day we might receive a signal from a foreign transmitter, a visit from an unfamiliar ship, a message from another dimension. But for now, as intelligent life forms go, humans are the only ones we know.