by Abhinav Sukla, Student Editor

The Fermi Paradox refers to a simple question that has eluded us all for decades: If aliens exist, then why haven’t we seen any yet? Billions of Earth-like planets exist in the Milky Way alone, and if life is a fraction as common as we believe it to be, our galaxy should be filled with alien civilizations in various points of development. Obviously, this is not the case, so the question the Fermi Paradox poses is “what went wrong?” Most people agree that there are only two likely answers. Either the development of life is significantly rarer than we previously believed, and we are truly the only intelligent beings thus far in our local pocket of the universe’s history, or there is some sort of “Great Filter” that kills off the majority of species. I’m going to explore both of these possibilities and then share my thoughts on them.

Although we are aware of most of our evolutionary history, the likelihoods of some of these processes occurring remains unknown. For example, abiogenesis, or the process of life emerging from non life like we believe it did on Earth, might be exceedingly uncommon. It is possible that the factors that allowed for this have only lined up once, and it happened here on earth. Other stages of our evolution also have the potential to be far rarer than expected. The evolution of eukaryotes(cells with nuclei), which are essential to multicellular life, only happened once on Earth. Multicellularity arose precious few times as well. And, of course, out of the millions of species that roamed Earth, intelligent life only appeared in one of them(us). If these processes are exceedingly rare on their own, and Earth has the optimal environment to encourage them, other planets that might have less ideal conditions than ours could be incapable of developing intelligent life, as multiple processes could keep their native species locked in an inferior stage of development. The evolutionary argument is widely regarded as the most likely explanation for the Fermi Paradox, but others propose a more ominous one: the Great Filter. 

Some experts posit that throughout a species’ development, it encounters several “filters” or major obstacles that prevent it from progressing to the next stage of life. The Great Filter refers to the largest of these filters, the one that typically holds a species back. This filter may be something behind us, such as the attainment of intelligence or abiogenesis, which shines a brighter prospect on our future. However, it could just as well be something that lies ahead of us, whether it be nuclear war, AI, or environmental catastrophe. If it lies ahead, some argue, it could be the answer to why there are no visible spacefaring civilizations in our universe. Perhaps none of them were able to break past this filter, and they were forever doomed to the confines of their planet or even extinguished entirely. 

Now that I’ve laid out the two main theories, I want to talk about what I think. Of course, there is some overlap in both, but most supporters of the Great Filter seem to think it lies ahead of us, so I think it’s safe to consider these separate arguments. I personally believe the evolutionary perspective is far more logical and likely. In my opinion, it is a mistake to believe that we would possess even an inkling of an idea of the motivations and psychology of an alien species. There is no guarantee that a species with our intelligence level will develop the exact same technologies on the same level. One species might shut down the idea of nuclear weapons before they ever come to fruition. Another might do the same with AI. A third could recognize the collapse of its environment due to industry and rush to fix the problem. Others might never explore these possibilities at all. Because civilizations could take such different developmental paths, I find it unlikely that there is a single universal filter that wipes out nearly all of them. On the flip side, the evolutionary argument shows us just how much we don’t know about our own ascension to intelligence. Without thorough simulations to ascertain the exact probabilities of abiogenesis or other processes, any one of them could be the secret to the Fermi Paradox. Regardless of which viewpoint you support, however, one thing is true: For now, we are alone in this universe.