The Fermi Paradox

The Fermi Paradox

“Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.” ― Arthur C. Clarke.

I thought I would add this article, as this topic has fascinated me for years.

Of all the questions about the cosmos, the Fermi Paradox surely has to be one of the most thought provoking.

The question it poses is a simple one; Where are all the aliens?

At first, it is easy to write off such questions as mere fantasy and not worthy of further serious study; only useful to become the pulp plots of the science fiction genre. Surely there are things more worthwhile and tangible for humankind to fret about than “little-green-men”. Curing cancer, longer life, world peace, the list is virtually endless.

However, to those that truly stop and think about the problem, the arguments at the core of the paradox go to the heart of reality itself, and ultimately our place within it.

I do not think that we hold some special place in nature, or that a divine being created the entire cosmos just for our benefit. We are a phenomena born of the same materials, energies, and rules that govern the rest of the cosmos, from the smallest speck of dust to the largest galactic cluster. Surely those same conditions could quite as easily have created intelligent space faring life elsewhere. If it happened here, then why not elsewhere. Seems simple enough.

In this short article, I seek to outline the question itself and to dive just a tiny bit below the surface to discuss why this isn’t just a trivial “I wonder” question.

A casual question over lunch

The legend of the Fermi Paradox begins sometime during 1950 with a casual conversation between the renowned physicist Enrico Fermi and his colleagues at the Los Alamos National Laboratory.

The Italian born Enrico Fermi won the Nobel prize of Physics in 1938, the same year that he left Italy to avoid new racial laws about to be brought in by the government of the fascist dictator Mussolini. If they remained in Italy, these laws would affect his Jewish wife. 

They emigrated to the USA, and during WWII Enrico was a key member of the team that worked on the Manhattan Project that would ultimately go on to create the first atomic bomb. We are not here to discuss the ethics of nuclear power or weapons. I will leave that debate to others.

We can’t be entirely sure of the exact circumstances surrounding the genesis of the paradox but it is reported that whilst at lunch with his colleagues the conversation turned to the reports and stories of aliens and UFO’s that were currently popular in the media. The conversation soon drifted onto other subjects, but a seed had been planted in Enrico’s mind.

Later on, during lunch, it is reported that he exclaimed to the group “Where is everybody?”

His colleagues knew exactly what he meant; Where are all the aliens?

Humankind has been around for less than a million years but the universe is much much older. Billions of years older. We are used to thinking in time scales in the order of decades, hundreds and occasionally thousands of years. Concepts of millions and billions of years are almost too abstract to truly imagine.

This may be because with lifespans of less than 100 years our brains, psychology, and history have evolved to thinking within this narrow scale.

We maybe simply not “geared” to think in cosmic timescales.

The problem Fermi had stumbled upon was this: If life is reasonably common in the galaxy and the universe has been around for billions of years, surely one intelligent space-faring species would have survived long enough to spread out into the wider galaxy. And if life was common, it should be everywhere. 

Any sufficiently advanced technology, freed from the constraints of being bound to a single planet, has the potential to become galactic. With ships travelling much slower than the speed of light, a species could visit or colonise the entire galaxy within 10 or so million years.

This might seem like a huge amount of time to us, but compared to the age of the universe this is almost no time at all. Indeed, look at how far we have advanced technologically within the last 100 years. Surely by now, the galaxy would be colonised by many species and evidence for their existence would be everywhere.

But here we are 13.8 (ish) billion years after the big bang and we see no evidence of alien life existing, or have ever existed.

When the Paradox was first conceived in the 50’s it wasn’t at all clear how many planets existed within our galaxy capable of supporting life. To be honest, it’s still little more than guesswork, but since that time we have discovered literally thousands of worlds outside of our solar system. It will only be a matter of time before we see one similar Earth.

The number of confirmed planets grows each day. We have surveyed a vanishingly small percentage of the galaxy so far. There are estimated to be over 100 billion (Yes, billion!) stars in our galaxy alone. If only a small fraction of those had life-supporting planets, and of those only a small fraction harboured intelligent life, surely there must have been many civilisations during the long history of the galaxy.

Just one. Just once.

So, where are all the aliens?

Remember, all it would take is one species. One species to have arisen at some point in the last 13.8 billion years that has survived long enough to spread its wings, arms, or tentacles, out into the galaxy. It doesn’t really matter what speed their ships were travelling at either, 1% the speed of light, 20%, 90%. It doesn’t matter. At any of these speeds, it would still be possible to explore and colonise the galaxy in a few millions of years.

Just because we aren’t used to thinking in these timescales doesn’t mean someone else isn’t. All it takes is one species… But where are they?

These explorers might also be non-biological. Freed from concepts such as boredom and lifespans.

We are ourselves on the cusp of being able to create machines that can act autonomously within space. What could we achieve in another 100 years? 1,000 years? 10,000 years?

The rise of 3D printers has opened up the possibility that we might soon be able to create something that would be able to gather resources and create copies of itself (see Is it unfeasible to imagine another species able to do the same thing?

Again, think how far we have come since 1900. Compare that again to the time-span of the universe.

As a technological species grows (as we continue to do so), it is possible that it might want to consume all of the energy from it’s sun. A so called Dyson Sphere (see, or Dyson Swarm would be visible to our telescopes. And yet, we see nothing.

What happens if that species was able to keep replicating, spreading and consuming. Would they then be able to manipulate the layout of their host galaxies themselves?

It seems far fetched, yes. But, consider again the sheer vastness of space and time. If complex life is common then there has been ample time for a species to do just that. Yet, we look across the vastness of cosmological time and space and see no evidence of anything.

But they were stopped by X,Y or Z

There are a thousand+ reasons why any given civilisation might not rise to do as we have imagined.

Maybe life is rare. Very, very rare. But again, it would only have taken one species to do it. Once.

Maybe they aren’t interested in exploration, or colonisation.

Maybe there is a law between civilisations that forbids self replicating robots, or contact with other less advanced species. Like some kind of cosmological Prime Directive.

Maybe they destroyed themselves. It’s possible. We are making a good job of harming our environment. Maybe they did the same.

Maybe they were killed by X. Or Y. Or maybe Z.

The problem with the reasons that anyone can come up with is that they have to work 100% of the time, every time. If one got through, then many will have.

This is known as the Great Filter. Sounds scary? It is. (see )

Are we alone?

Are we alone in the universe?

Are we the first intelligent species to have arisen?

Is there something “out there” that is stopping species from advancing past a certain point?

Is the galaxy actually full of alien life but for some reason we just can’t see them or recognise them? Is intelligent life just vanishingly rare? So rare that we are essentially alone in the universe.

These are all questions that the Fermi Paradox raises.