Answer: Extraterrestrial Life

The Fermi paradox is named after Italian physicist Enrico Fermi. Although Fermi is best known for his very influential contributions to the field of nuclear physics (and is frequently referred to as the architect of the nuclear age), the Fermi paradox has nothing to do with nuclear physics and everything to do with the search for extraterrestrial life.

Specifically, the paradox is the apparent contradiction between the lack of evidence for any extraterrestrial life and the high probability estimates (such as those outlined by the Drake equation) for the existence of extraterrestrial civilizations. The paradox’s argument, put together by Fermi and fellow physicist Michael Hart is such: there are billions of stars like our Sun, there is a high probability that some of these stars will have Earth-like planets, Earth-like planets have the potential to develop life, life can evolve to the point that it begins traveling the cosmos, and even factoring in the current level of envisioned interstellar travel, the Milky Way galaxy could be completely traversed in about a million years. So why have we never encountered any evidence of alien life? Or, to simplify it even further, Fermi himself once distilled the entire paradox down to the simple question: “Where is everybody?”

Naturally, there has been more than a bit of discussion devoted to answering that simple question. Where, indeed, is everyone? There are a wide variety of explanations for the Fermi paradox. There’s the Rare Earth hypothesis: the argument that the conditions necessary for evolution and biological complexity are exceedingly rare in the universe. Then there’s the idea that no other intelligent species have arisen in the first place or, that if they have, they lack the advanced technology to broadcast their presence to the universe or begin traveling through it.

Rather grimly, there’s an argument that it is the destiny of intelligent creatures to eventually destroy themselves, so, long before a species is advanced enough to traverse a galaxy, they’ve likely done themselves in with war or environmental contamination. Building on the grimness, there is a sister theory to the aforementioned argument that much like we’ve wiped out other species in our domination of planet Earth, other alien species could be doing the same thing on a galactic level (decreasing the number of civilizations that could reach out to us in the process).

Just those few theories barely begin to scratch the surface of the arguments as to why we haven’t encountered intelligent life (let alone any life) in the universe so far, but one thing certainly stands: over sixty years after Enrico Fermi posed the question “Where is everybody?”, we still don’t have a good answer for him.