The Fermi Paradox – Where Is Everybody?

Our universe is 13.8 billion years old. Space travel gets easier over time. Earth should have been visited by aliens by now. So where the hell is everybody? This is the Fermi Paradox.

The universe is enormous. There are unfathomable exoplanets – planets orbiting stars outside our solar system – at unfathomable distances, with more being discovered every day. It’s thought many of these exoplanets could sustain conditions habitable for life. Surely, somewhere, one of them holds intelligent life. But we haven’t found any aliens. And they haven’t found us. 

It isn’t for lack of trying. We’ve spent the better part of a century pursuing space knowledge. One motivation behind space exploration is an aim to colonise the stars. Because apparently we can’t just leave things alone. But another aim is to make contact with other intelligent lifeforms. These lifeforms, we presume, would also be busily building empires in the sky. What else would an intelligent lifeform do with its time?

In 1950, Nobel Prize-winning physicist Enrico Fermi was chatting aliens at lunch with colleagues. He made an off-hand statement that there was a high probability the universe was filled with sophisticated societies. 

This assumption, reasonable given our then-and-current knowledge of the galaxies, provoked for Fermi a compelling implication: if there are lots, surely some would have travelled. Scientists have theorised an intelligent civilisation could take about 10 million years to evolve and develop – surely at least one alien society would have developed the technology for space exploration and used it to conquer the galaxy by now. Ten million years would be more than enough time – hardly a blip on the timeline of the universe, which is ten times that. 

This was Fermi’s unanswerable paradox. If all of the known possibilities for the advancement of intelligent life are out there, why are we all alone?

Aside from inventing the Search for Extraterrestrial Intelligence’s (SETI) personal existential crisis, Fermi is also known for creating the world's first nuclear reactor, the Chicago Pile-1. He’s been called both the “architect of the nuclear age” and the “architect of the atom bomb”. He was awarded the 1938 Nobel Prize in Physics for his work on making normal things radioactive and discovering transuranium elements, which are used in nuclear weapons. 

During World War II, Fermi worked on the Manhattan Project – the US-led research and development undertaking that led to the first nuclear weapons. He worked under J. Robert Oppenheimer and was one of the scientists who testified at his 1954 hearing. So… That’s Fermi.

Fermi basically dropped his paradox and dipped. He died in 1954. A decade later, planetary scientist Dr Frank Drake presented the Drake equation.

The Drake equation attempts to estimate the number of advanced alien civilisations in our galaxy. As written in Encyclopedia Britannica, it looks at the mean rate of star formation in the galaxy, the fraction of stars with planetary systems, the number of planets in such systems that are ecologically suitable for the origin of life, the fraction of such planets on which life actually develops, the fraction of such planets where life evolves to an intelligent form, the fraction of worlds in which the intelligent life form invents high technology capable at least of interstellar radio communication, and the average lifetime of such advanced civilisations. Or, R* = 10/yr, fp = 0.5, ne = 2, fl = 1, fi fc = 0.01, thus N = L/10.

The equation is dependent on wide variables. If it’s predicted that civilisations typically destroy themselves within a decade of achieving radio astronomy – the defining marker of an advanced civilisation – then there are no other life forms in the galaxy. If it’s assumed that just one per cent of civilisations figure out a way to live with that technology without destroying themselves, then there are 1,000,000 advanced alien civilisations out there, and the nearest are just a few hundred light years away.

When Drake presented his equation, it was estimated there were somewhere between 1,000 and 100,000,000 civilisations in the observable universe. These vary widely because the only variables scientists know with any certainty are the rates of star formation and the number of exoplanets in the galaxy.

In 2016, the discovery of new exoplanets prompted a paper that revisited the Drake equation. Scientists found that human civilisation was likely to be unique in the cosmos only if the odds of a civilisation developing on a habitable planet were less than around one in 10 billion trillion. With odds that slim, the researchers told NASA there was a good chance an alien civilisation had developed. 

In an interview with NASA, professor of physics and astronomy at the University of Rochester, and co-author of the paper Adam Frank, said: “Of course, we have no idea how likely it is that an intelligent technological species will evolve on a given habitable planet. 

“But using our method we can tell exactly how low that probability would have to be for us to be the ONLY civilisation the Universe has produced. We call that the pessimism line. If the actual probability is greater than the pessimism line, then a technological species and civilisation has likely happened before.”

Other scientists have posed answers to the Fermi Paradox. Michael Hart wrote an article titled "An explanation for the absence of extraterrestrials on Earth". Published in the Royal Astronomical Society Quarterly Journal in 1975, Hart suggested aliens don’t exist because we can’t see them.

He also outlined four potential explanations for the Fermi Paradox:

• Aliens never came here because of a difficulty that made “space travel infeasible” – which could be related to astronomy, biology or engineering.
• Advanced civilisations beyond Earth arose too recently for aliens to reach us.
• Aliens have visited Earth in the past, but we have not observed them.
• Aliens simply chose never to visit us.

SETI is the collective term for scientific research into the existence of intelligent life that seeks to answer the question: are we all alone?

SETI efforts kicked off shortly after the invention of radio in the early 1900s, when people began to suggest radio waves could be used to contact Martians. The first practical SETI experiment was Project OZMA in 1960. Headed by Frank Drake, the project used a radio telescope 26 metres in diameter to listen in to two stars. Nothing of interest was recorded.

In 1971, NASA formed a SETI study and in 1977 the Ohio State SETI program made world headlines when it uncovered an ultra-strong 72-second radio signal on a telescope. Known as the Wow! Signal – an image of the signal was printed out and the phrase “wow!” hastily scribbled in its margin – the signal is thought to be the closest we’ve come to receiving communications from outer space. Alas, research papers have since declared the controversial signal was the sound of a passing comet.

We have also sent signals into space in the search for life, including the Arecibo signal, the most powerful message ever beamed into space, which was a digital message describing a cheat sheet to humanity: the numbers 1 to 10, the basic chemistry of life on Earth, the structure of DNA, Earth's population, a graphic of the Solar System, a human figure, and a graphic of the Arecibo radio telescope and it's dish' dimensions. Designed by Frank Drake, the Arecibo message was sent to the star cluster M13, roughly 21,000 light-years away. In 2008, “A Message From Earth” time capsule containing 501 messages from around the world, selected through a competition on Bebo, was sent toward the exoplanet Gliese 581c. It’s expected to reach the star system in 2029.

The search continues. But while we’ve been looking for decades, studies have shown that, comparable to the universe’s size, we’ve only looked in one minuscule corner. 

Perhaps the most disturbing solution to the Fermi Paradox is the Great Filter. Economist Robin Hanson first proposed the theory in the late 1990s, suggesting that even in the case that life formed abundantly in our galaxy, any extraterrestrial species would inevitably face a great barrier to its survival, or, destroy itself. This could come from outside society’s control – asteroids, weather events, their planet exploding – or from within – nuclear war, viruses, the devoted architecture of a climate crisis through the burning of fossil fuels… Very weird alien stuff that absolutely definitely would never happen to us humans. 

In 2018, research from Oxford University’s Future of Humanity Institute rejigged the Drake equation and found there was actually quite a high chance we are all alone in the visible universe – between 38 and 85 per cent. It also found there was between a 53 and 99.6 per cent chance we’re completely alone in our galaxy.

The blank silence from our stars is difficult to ignore. But our 60s sci-fi optimism in the search for intelligent life continues. 

We’ve spent decades imagining what’s out there, while what we have down here has deteriorated with each passing day. Maybe there is life out there, but no intelligent species has seen a need to build an empire or colonise the stars. Maybe they’re not in the same dimension as us. Maybe they’re all around us. Maybe they have checked us out and they just don’t like what they’ve seen. When one asks the other “Should we visit that tiny blue planet?”, the other shrugs, “Fuck that. The Great Filter will get them soon.”

But maybe there really isn’t anyone out there. No alien civilisation to hear our little human calls. No alien civilisation to whisk us off to another planet. No alien civilisation to save us from ourselves.

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