It all started while Enrico Fermi was having lunch. Fermi was an Italian guy who was both one of the best theoretical and experimental physicists (most people prefer one over the other) alive at that time. In fact, he had invented the world’s first nuclear reactor 8 years prior and had won the Nobel Prize in 1938, so we can assume whatever he was talking about at lunch was being taken seriously by his fellow physicists. He wanted to know where everybody was. He realized that, taking the size of the Universe into account, there were probably several civilizations out there. If there was a single one with technology sophisticated enough, it could rapidly colonize our entire galaxy within a few million years (less than a blink of an eye in the cosmological scale). So, why don’t we see anybody?
This seemingly innocuous question has been keeping scientists intrigued for a few decades now and, so far, we don’t have any satisfactory answer for why we don’t see little green men wandering around us. In a matter of fact, even the Greeks were kind of startled by this. Metrodorus, disciple of Epicurus, once said: “To consider the Earth as the only populated world in infinite space is as absurd as to assert that in an entire field sown with millet only one grain will grow.”.
In 1961, the American astronomer Frank Drake decided to create an equation to quantify the probability of contacting with extraterrestrial intelligence. The original Drake equation was as follows:
You don’t have to worry about the mathematical jargon, just bear this in mind: according to this equation, the number of civilizations we ought to communicate with is astonishingly huge. Carl Sagan estimated there should be one million civilizations! One million! But where the hell are they?! No scientist has the same answer to this question, some say we are the only ones in the entire Universe, others say we don’t even share the same means of communication as the other civilizations or that we were already contacted by them in the past.
All of those ideas are nothing but mere hypotheses based solely in the only life we know of: life on Earth. Therefore, we cannot conclude anything by having such little information of the Universe we live in. Detecting extraterrestrial intelligence would, undoubtedly, be the greatest event in Human history, but, the absence of such communication, would never prove there aren’t any extraterrestrial civilizations out there. We should seek to reach the little green men that may well be living in our very own galaxy, or prepare for an eternity of solitude.