One day, in the year 1950, a few physicists were gathered together enjoying their lunch and making casual conversation. At some point, their conversation arrived on the debate of extraterrestrial life in our galaxy; are we alone in our galaxy? They listed all of the facts as they knew them. 1) Our Milky Way Galaxy is approximately 13 billion years old, 2) Earth is only 4.6 billion years old, therefore, there was approximately 8 billion years for life to develop in other parts of the galaxy before Earth even existed. Given the relatively short amount of time it would take for life to arise and evolve into a highly intelligent species within those 8 billion years before earth, they arrived at the conclusion that it is extremely probable that there is other intelligent life in our galaxy that has existed long before us.
One physicist at the table was taking all of this conversation in, but he became puzzled. He thought about the history that humanity has of exploring and conquering our world to expand our empires and answer our own scientific questions. And we continue to show much interest in exploring beyond our world as well. In fact, given the capability, it would seem that we would travel and explore the whole galaxy, regardless of how long it would take. He thought that if this was the case for us, other intelligent life must also share this curious and exploratory nature. It’s estimated that a single intelligent species could conquer the whole galaxy in as little as 10 million years. So if it is highly probable that intelligent life exists outside of earth and has possibly existed for billions of years before earth, then why is there no observable evidence for the existence of intelligent life outside of Earth? Why have we not seen them or any evidence of them at all yet? This is the question that the physicist, by the name of Enrico Fermi, asked his colleagues this day in 1950. If life is so probable, then where are they? This question would come to be known as Fermi’s Paradox.
Before I go any further in discussing Fermi’s Paradox, I want to simply preface that I will not be making any scientific claims using Fermi’s Paradox, as I don’t believe that was Fermi’s intention when he posed this question. My goal for the remainder of this post will be to briefly and objectively discuss the implications of Fermi’s Paradox from a variety of angles, following logical lines of thought to examine some ways we can answer the question. I am not a physicist, so I will not be approaching this scientifically, but rather from a philosophical perspective as a thought exercise to see what Fermi’s Paradox could mean in the debate of the existence of extraterrestrial life.
This may seem like such a simple question and really it is. I think it’s a question that everyone has asked at one point when they are discussing the possibility of intelligent life in our galaxy and even our universe. I think that if asked, the majority of people would say that they believe we are not alone in the universe. After all, that seems to be the most logical answer based on the current data we have about life and the probability of it forming somewhere else in our massive universe. Even when you ask specifically about life in our own galaxy, which itself contains billions of solar systems with many earth-like planets that could harbor life, most people would say that they think there is intelligent life in our galaxy. This, again, seems to be the logical choice as shown by the numbers that I talked about at the beginning of this post. It seems much more likely that we are not alone than it does that we are alone.
However, with our natural drive to explore and learn, it also makes sense that if there was other intelligent life in our galaxy, we would have seen signs of it by now. So which is it? Is there intelligent life or are we alone? If the former is true, then that life must not care about learning more about our universe. This would suggest that they do not have an interest in learning, or even really advancing as a society. And depending on how you define “intelligent life”, this very likely would no longer fit the criteria. The only other option, if we are not alone, seems to be that the extraterrestrial life is less evolved as a species than humans, meaning they formed after humans. In order for this to be true, humanity would have to be the first intelligent species in our galaxy; however, when we think about how long our galaxy existed before earth, this seems like a very naive belief. On the other hand, if the latter is true and we are alone in the galaxy, chances go up that we are also completely alone in our entire universe. We would then be either a highly unlikely cosmic mistake, or we must be something special that was created intentionally. Both options carry heavy weight in terms of what they would mean for humanity.
Through the years, physicists have tried to come up with a solution to reconcile Fermi’s Paradox, but have every time fallen short of a satisfactory answer. We have come up with equations that estimate the probability of discoverable life in our galaxy and the results usually yield hopeful results, and yet Fermi’s Paradox still remains. Is there other intelligent life in our universe? Perhaps the answer is that we will never know. Or maybe, 10 million years from now, humans will spread out across our entire galaxy and only then will we truly know the answer to the question of intelligent life in our galaxy. But for now the question remains in the back of all of our minds: “If they’re out there, where are they?”