When humans look up into the night sky and think about the vast cosmos, it’s hard not to wonder what else might be out there. Indeed, we can’t be the only life in the universe, right? Countless sightings of UFOs and descriptions of encounters with aliens have led to an overwhelming sense that there must be some life from beyond the stars interacting with humans regularly.
However, when you turn your telescope to the sky, you’ll see no evidence of advanced life forms anywhere else in the galaxy. We see no Dyson Spheres, no great alien superstructures blocking the light from distant stars. The vast, unknowable cosmos seems empty, aside from our blue home. Where is everyone? Today, we’re talking about the Fermi Paradox.
The Fermi Paradox, named for its inventor, famed astrophysicist Enrico Fermi, holds that two things are true: there is no evidence of alien life, and there is a high likelihood that there is alien life.
Fermi concluded that the vast number of stars in the observable universe, and the likelihood that at least some of those stars have Earth-like planets, and at least some of those Earth-like planets could have seen evolution like our own; that it’s very strange that we don’t see evidence of other intelligent species in the stars.
Fermi’s confusion compounds the fact that the sun is relatively young, and the advent of intelligent life on Earth is a very new development. Some sun-like stars have existed for billions of years, and it’s distinctly possible that intelligent life could have evolved on planets around those stars while the Earth was still cosmic dust.
This is all to say that, if the experience of humans on Earth is remotely familiar in the galaxy, there has been plenty of time for an advanced species to travel across the entire Milky Way and visit the Earth. But, there’s no evidence that this has ever occurred. So, what gives?
One possibility is that life is exceedingly rare. The evolution of complex life may occur so infrequently that humanity is the first intelligent species to create vessels capable of space travel. Maybe we are alone in the universe.
Since our sample size for intelligent life is “one,” it’s hard to make any definitive conclusions regarding this hypothesis. Maybe there is intelligent life elsewhere, but advanced species are unconcerned with expanding into space.
Another proposed solution to the Fermi Paradox theory is that something prevents life from attaining an advanced proficiency with technology.
This theory, called The Great Filter, holds that something must keep life from ever getting to the point where it can spread across the stars.
Perhaps space travel between star systems is even more complicated than we’ve predicted. Or, maybe most intelligent species accidentally destroy themselves with nuclear war or biological accidents before they can master space travel.
Whatever the case may be, the paradox stands. The universe should be teeming with life if our experience isn’t completely abnormal. Where are all the aliens? Why do we seem to be so crushingly alone in the vast cosmos?