Why we aren’t alone in the universe — but might as well be

Are we alone in the universe? The question has tugged at humanity ever since we discovered the enormity of the cosmos.

In 1950, Enrico Fermi postulated his famous paradox: If life is common enough in the universe to give rise to us, then where is everybody? Recently, a philosopher has advanced a proposal to resolve this paradox: We are not alone in the universe, and there are many alien civilizations out there. But they wisely choose to keep to themselves. 

Fermi’s paradox relies on an idea called the cosmological principle, which is a general attitude in astronomy and cosmology that we do not occupy a privileged position in the universe. We live on just another planet orbiting just another star in just another galaxy. But by that logic, life — and even intelligent life — should be common. After all, there’s nothing remarkable or special about our status in the universe, including our own existence. 

But if life is common, then the galaxy should be swimming with intelligent civilizations. We arose to intelligence only a couple hundred thousand years ago, while the Milky Way Galaxy has been around for roughly 9 billion years. There should be ample evidence everywhere of intelligent alien activity. 

But the galaxy is silent. We see no evidence despite decades of searching. So where is everybody?

Scientists and philosophers have come up with many ways to tackle this apparent paradox. Perhaps there is some great filter that prevents intelligent civilizations from spreading across the galaxy. Or perhaps we are much rarer than we think. 

Related: What happens if we detect alien life?

Reasons not to expand

Adding to this discussion is philosopher Wolfhart Totschnig, who recently published an argument that claims to resolve the paradox in a different way. In his perspective, intelligent life is indeed common throughout the universe, but also that we are incredibly unlikely to find any evidence for it. 

The work appears in Acta Astronautica.

His argument relies on rebutting one of the foundational assumptions of Fermi’s paradox: The assumption that an intelligent species will spread itself as far and wide as possible. At first glance, this is a solid line of thinking, since biological organisms tend to do just that — they reproduce and spread to fill every available niche. Intelligent civilizations should follow that fundamental biological principle and, once given the opportunity to colonize the stars, should do so as quickly as possible. 

But Totschnig argues that this expansion is not a necessity. Intelligent civilizations have something that simple organisms lack: culture. And in fact, the cultural evolution of our species far outpaces biological evolution. We have acquired new traits, learned new skills, and filled new ecological niches — not through genetic adaptations but through aspects of our culture like stories, clothing, and housing. 

Totschnig argues that any intelligent species will recognize that spreading across the galaxy as quickly as possible is generally a bad idea. The ability to reproduce would easily outstrip the ability to populate new worlds and gather the necessary resources. There are only so many planets that offer the right conditions for life, and so conflict is inevitable and unavoidable.

What’s more, intelligent life will only become more dangerous to itself with time. We’ve barely left planet Earth and already we have the capability with nuclear weapons to render our entire planet uninhabitable. What might a civilization thousands of years more advanced than us be capable of? 

Advanced civilizations will see the risks of self-annihilation posed by rampant expansion and develop cultural tools to prohibit that expansion. Already we see such tendencies on Earth. Generally the wealthier and more prosperous a country becomes, the lower its birth rate. Continued expansion and rapid population growth are not necessities, and cultural factors and influences exert their own pressures to reduce the spread of populations.

All in

Totschnig further argues that it is not sufficient for only a fraction of civilizations to inhibit their growth. That’s because if any proportion of them, however small, ignores these cultural inhibitions and spreads as relentlessly as possible, they will simply overwhelm all the other galactic civilizations and make themselves noticeable. Instead, Totschnig argues that essentially all civilizations develop the necessary cultural and political forces to slow their growth and limit their presence to only a small fraction of the galaxy.

This resolves the Fermi paradox because it allows for intelligent life to be as common as we naively expect it to be, but also for that intelligent life to not leave behind any artifacts or evidence for its existence. It means that intelligent life is out there, with hundreds or even thousands of civilizations occupying our galaxy at any one time, but they are relatively mute and undetectable to each other. 

So, in essence we are not alone in the universe, but we might as well be.

Related: The Drake equation: What are the odds that aliens exist?