“Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.” - Arthur C. Clarke

Are we alone in the universe? This question has perplexed humanity since we’ve discovered our place among the stars, on a lonely planet in a seemingly infinite, boundless expanse. Through the improbability, we are here now, alive and looking to the stars for answers. Surely there must be others like us out there? There are up to 500 billion planets in our galaxy alone, and almost 10 billion of them are similar to our own. And most of them are much older than the Earth, surely there must be living beings like us who have developed far more advanced technology… But so far, there’s nothing. In a universe that should be bursting with life, we haven’t found an iota of evidence that suggests that life exists beyond our planet. No remains of previous civilizations, no signs of alien technology, not a single whisper from the cold, dark vastness of space. So, where are they?

The Great Filter is one possible answer to this question. We can visualize a species’ journey as steps on a ladder. For us, our journey began when we were single cell lifeforms swimming around in primordial soup. Through millions and billions of years of evolution, we managed to become more complex, multicellular lifeforms, and eventually become the dominant, intelligent species of our own planet, which is where we are today. In the future we might learn to harness the potential of our own planet, and eventually the sun itself… Providing us with the necessary energy needed to finally reach other stars and become an interplanetary species. This is the template on how a species would grow and spread itself throughout the universe, all these steps that a species takes that takes them higher and further in an interplanetary scale. But because our planet seems to be the only one so far to harbor life, there must be some important things else we are yet to figure out. This fact suggests that there is a bottleneck, a great wall that’s nigh impossible to pass through somewhere in life’s journey, an evolutionary leap that no species have succeeded in making. That bottleneck is what we call the Great Filter.  

And so finally the question is raised, are we just incredibly special and lucky? Is the emergence of life a statistical impossibility before we beat the odds? Are we the first ones out there, and therefore alone in this stage of our existence? For the continued survival of our species and civilization, this would be the preferred scenario. It would mean that we have overcome the impossible, the Great Filter is safely behind us… That the countless worlds scattered throughout the universe are simply empty, just waiting for humanity to finally discover them and fill them up with life.

This is why if at some point we discover that life exists somewhere else in the universe, say some microbial life forms or cute alien dogs, it’s incredibly bad for us. If we find advanced civilizations or the remains of one, it’s far far worse. For it would mean that life isn’t as incredibly rare as we thought, that we were not the first and definitely not the last “advanced” civilization to exist in this universe. That the intimidating Great Filter is something we have yet to experience.

If the Great Filter does truly lie in front of us, then we may just as well be doomed. Somewhere in our future, there lies a challenge so great that no other species have triumphed over it. Something so dangerous, deadly and inescapable that it left us as only the next young, wide-eyed new species unawaringly marching forward towards our own inevitable destruction. If the Great Filter is yet to be faced by humanity, I hope that we somehow rise to the occasion and overcome the impossible challenge in front of us.