Nobody’s found signs of alien life yet. So why do they keep on looking?

Extra-terrestrial life. What images just popped into your mind? Little green men? ET, the gnarly but ultimately friendly alien? My own mind bombards me with characters from my beloved Marvel comic books: Aesir, Kree, Skrull, Chitauri, Celestials, Watchers —

Okay. I’ll stop.

My point is that extraterrestrial life is widely considered to be a thing of fantasy, a plot device associated with the likes of Arthur C. Clarke or Isaac Asimov. Someone who claims to have seen a UFO, or some other such indicator of alien life, is generally believed to be about as nutty as a fruitcake.

Of course, if that someone happens to be a professional scientist, then the situation is somewhat different.

In 1967, Jocelyn Bell, then a graduate student trying to wrap up her astronomy PhD, noticed a strange signal coming through her radio telescope. It repeated about every 1.3 seconds and kept time better than atomic clock — which uses the vibrations of an element like caesium as a timekeeper and is very, very regular.

Most signals picked up from deep space are quite chaotic, and don’t follow a fixed pattern. They also usually radiate across a wider frequency, as opposed to the very specific one this signal occupied.

Whatever this signal was, it didn’t look natural.

That’s why her supervisor, Antony Hewish, along with a few other scientists, named the signal LGM-1, where LGM stands for Little Green Men. They thought they had stumbled upon the first signals from an alien civilisation.

A little investigation on Bell’s part proved differently. What she had found turned out to be a pulsar, the radio waves from a dying neutron star 5.5 million years ago.

Hewish recieved the Nobel Prize in 1974 for the discovery. Bell did not.

As recently as 2016, scientists studying the dimming patterns of a star thought they might have found evidence that there were giant structures built on its surface. At that time, nothing else explained the phenomenon as well as aliens did. Or so they thought.

It turned out to be dust.

These are just some examples of incidents where scientists think they’ve found aliens, until they find that they haven’t. It’s certainly happened more often than you might expect.

So why do they keep looking?

There are approximately 100 thousand million stars in our universe. Here’s what that number looks like:

10,000,000,000,000,000,000,000.

Mind boggling, right? To put it in perspective, that’s 10,000 stars for every grain of sand on planet Earth.

That’s a lot of potential for life.

We could even narrow it down to only the stars that are similar to our sun — with similar size, light, and temperature. A conservative estimate tells us that’s about 5% of all stars, which still leaves us with 500 billion, billion suns.

That’s…still a lot of potential for life.

In 1930, Clyde Tombaugh discovered a small, icy body orbiting beyond Neptune. He had been searching for a body that was supposedly causing small shifts in the orbits of Uranus and Neptune, at the prediction of Percival Lovell. The body he found was not the one he had been looking for after all — it was the wrong size and wrong orbit — but it was an important discovery nonetheless.

He had discovered Pluto.

Until 2003, Pluto was thought to be it — the edge of our solar system and the last planet orbiting out sun — when another planet, larger than Pluto and possessing a moon of it’s own, was found.

Further investigation showed that Pluto was not quite as isolated as we’d previously thought, but was, instead, one among a vast series of bodies in what we now know as the Kuiper Belt.

It was kicked off the planet list by the Planet Definition Committee in 2006, formed to take a call on what might happen if we found more objects like, or even larger than, Pluto.

A likely possibility.

People don’t often appreciate just how far astronomy has come in the last few decades.

Until the 1990s, no one was able to say for sure that there were planets outside our solar system.

Then, in 1992, two astronomers at the Arecibo observatory detected what they were pretty sure was two faraway planets, orbiting a pulsar of the kind Jocelyn Bell found. Within three years, a planet had been found orbiting a star similar to our Sun. And then 2009 saw the launch of the Kepler Space Telescope, sending back so much data that computers were busy processing it long after the spacecraft had ceased its observations.

Today, scientists estimate that one in every five bodies that appear as stars that look like our sun, could be an Earth-like planet.

That means that there are a hundred billion, billion Earth-like planets.

That’s one billion potentially habitable planets for every dollar that Jeff Bezos is worth.

Ever heard that cockroaches could survive a nuclear apocalypse?

Well…they can’t. Not exactly, at least. However, they can withstand high amounts of radiation, up to a point. And they’re not the only ones.

Amoeba, wasps, and water bears (the microscopic kind — and they’re actually very cute) can all handle higher amounts of radiation. And scientists are finding life forms in increasingly extreme conditions.

Radioactive waste, boiling water near underwater volcanoes, hot tar, Antarctic ice, and gold mines several miles deep are just some of the unlikely habitats we’ve found so far.

What does this mean for our search for life?

Basically, that we can broaden some of our parameters. All these discoveries have shown us one thing: life doesn’t require very specific conditions to survive, or even thrive.

So how many planets can we expect to find with life on it?

Even if we say that one out of every thousand Earth-like planets has given rise to life, that leaves us with a hundred quadrillion possible planets.

And even if one in every thousand of those planets has birthed intelligent life — that is, life that’s able to produce radio signals such as LGM-1 — that still gives us a hundred potential planets for every dollar that Apple is worth.

Given these ridiculous numbers — and a probability of extraterrestrial life that’s, well, astronomically high — it’s time we stopped asking why people still search for aliens. A better question to ask might be:

Why haven’t we found them yet?

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