By: Cole Harstone
You’ve likely found yourself, at some point in your life, wondering if we’re alone in the universe. Luckily, you’re not alone. This question has perplexed scientists for centuries, and to this day, it still remains unanswered.
The Fermi Paradox explains that our math contradicts our observations and sums up to: “where are the aliens?”. Many hypotheses have been made, and some theories have been put forward, in an attempt to answer the Fermi Paradox. Despite this, the scientific community remains divided, and the question remains unanswered. Some scientists argue that alien life must exist somewhere, due to various estimates for their probability. The lack of evidence to back up these claims, however, leads others to doubt.
Even if intelligent life exists somewhere in the universe, it’s unlikely that we are going to come into contact with them anytime soon.
The Stairway of Life
One possible answer to the Fermi paradox is something called the Great Filter. The Great Filter was proposed by Robin Hanson in the 1990’s, and it is one of the more popular answers to the Fermi Paradox. The Great Filter is, in essence, “a challenge or danger so hard to overcome, that it eliminates [most, if not all species] that encounter it”. If you imagine the development of life as a staircase, every step represents a different challenge that every species must overcome. Just to give you an idea of what these steps represent, here are a few challenges that every species needs to overcome in order to become “a truly advanced, spacefaring civilization”:
- A planet must be habitable (to see what makes a planet habitable, check here)
- Life (usually basic, uni-cellular organisms, such as bacteria) must develop from dead chemistry.
- Simple cells (prokaryotes) must evolve into more complex cells (eukaryotes).
- Cells must work together to build complex, multicellular organisms
Although those are just a few of the many conditions that need to be met, there are many, many more. So, the Great Filter proposes that there is one challenge, one step so difficult for a species to overcome, it will wipe out almost every single species that encounters it. Even if that species has managed to overcome all the previous challenges. In other words, the Great Filter is the hardest step in planetary evolution. According to this theory, this is why we can’t find any evidence of alien life. The Great Filter has wiped out virtually every very single intelligent life form.
Where Are We?
There are only two trains of thought to answer the question: where does the great filter lie in relationship to us? The first option:
The Great Filter is Behind Us.
If the Great Filter is, in fact, behind us, then we could be the first species in the entire universe to make it to this stage. This would suggest that we are currently alone. Although this is a rather daunting idea, this is the ideal outcome for the preservation of the human race. Although it’s impossible to be sure, some people speculate that this is the case. This is also why we should hope not to find alien life. “The more common life is in the universe, and the more advanced and complex it is, the more likely it becomes that a filter is in front of us”.
The Filter is Ahead of Us.
If this is the case, it doesn’t look so good for us. It would almost certainly mean the end of humanity, as it is, after all the Great Filter. If it wasn’t a challenge that was actually difficult to overcome, then its much more likely that we would be seeing signs of intelligent alien life. It also has to be something that almost every species will encounter.
Nuclear War? Killer Robots? Superbugs?
It’s hard to determine what, exactly the Great Filter could be. Regardless of whether the Great filter is behind or ahead of us, it doesn’t make it much easier to pinpoint what it is. One popular theory is that the Great Filter is climate change. Perhaps intelligent species universally end up destroying their planet due to competition for resources or using their resources in excess. Either way, it seems like this might be the path that humans are headed down. If climate change is, the Great Filter, then humanity’s days are numbered.
If you’re interested in learning more, check out this great explanation of the Great Filter.