We all grew up watching E.T. the Extra-Terrestrial and I am certain a few of us cried as well when E.T went back. Then comes our not-so-friendly Alien series that some of us might be scared to watch. Despite all the fiction and some questionable YouTube videos, we have never found a single proof of life beyond Earth. There are about 300 million habitable planets in our galaxy alone, where life could develop and exist. So where is everybody? Shouldn’t our space be teaming with life just like Star Wars? The Fermi Paradox attempts to answer this.
Scientists estimate that the first planets formed around 12 to 10 billion years ago. Our Earth came into exitance only 4.5 billion years ago. This gives other habitable planets plenty of time to develop and evolve life. But we haven’t encountered any evidence of extraterrestrial civilization. What would a civilization from another planet even look like?
The Kardashev scale, originally designed by the Russian astrophysicist Nikolai Kardashev, attempts to answers this question. This scale is a measure of determining a race’s technological advancement. It is based on the level of energy that a specific civilization can utilize. There are three categories:
A type 1 civilization
This is the level of a planetary civilization that can harness all the power available on its planet. We are currently a type 0.7 civilization. According to the physicist Freeman Dyson as cited by Dr. Michio Kaku, it would take us about 200 years to reach type 1.
A type 2 civilization
This type of civilization can harness all the energy from its home star. This seems like science fiction, but it’s not impossible according to scientists who claim that structures such as the Dyson Sphere could one day make this possible.
A type 3 civilization
This god-like civilization would be capable of using all the energy available in its galaxy. They will be at the pinnacle of knowledge and evolution – controlling the whole universe.
Though it seems impossible at this point, it would take millions if not billions of years to colonize our galaxy. It seems like a long time, but remember that the milky way is huge. If it takes millions of years to colonize our galaxy and there are 300 million habitable planets, where are all the aliens? Why does space seem empty and dead? This is known as the Fermi Paradox.
We have no answer to the Fermi Paradox – only educated theories. One of such theories is known as “The Great Filter.”
A great filter is a natural or artificial barrier that makes it nearly impossible for life to exist. It can be a comet or an asteroid collision, nuclear war, gamma-ray bursts or some phenomena that we don’t know of. But whatever it is, it prevents civilizations from moving forward on the Kardashev scale by eliminating them.
Now the question at hand is whether we are ahead of the Great filter or behind it. If we have passed the filter, that would mean that we are unique. It is extremely rare for life to come to our level, and we will probably be one of the first – if not the first – to be a type 2 or 3 civilization. That is the reason any other life form hasn’t contacted us.
If this is true, then what was our great filter? Maybe it was the initialization of life itself that was the hardest task, because we still haven’t figured out how life began on our planet. Or perhaps it was the changing of simple prokaryote cell to the eukaryote cell, which took almost two billion years, but we don’t know for sure.
The next option and a rather terrifying one is that we are behind the filter and will have to face it at some point in the future. Maybe life on other planets did evolve to the point where we are or perhaps even further. But the great filter prevented it from going further, and we are no exception. Our fate will be the same as other civilizations who have come before us – destruction. This destruction might be at the hands of the universe or maybe our own doing.
On the other hand, some explanations keep the idea of type 2 or 3 civilizations existing alive. One of such explanations suggests that we are so behind on the evolutionary scale that type 2 and 3 civilizations don’t find any practical use in communicating with us. They must be so advanced that they might not even know we exist, or our methods of communication might be far outdated for them. We might be like the bacteria in their universe.
Another one suggests that the advanced extraterrestrial life is so intellectually superior that the concept of colonization seems pointless to them. With all the energy they utilize, they have created a safe space for themselves in their part of the galaxy and seem to be at peace without any outer intervention.
Then there are some theories that sound absurd but hold the same probability of being true as any other. One of such theories suggests an advanced alien civilization that keeps a check on the whole galaxy. And once a civilization reaches a certain technological point, they destroy it. They act as the great filter for other civilizations because they don’t want any competition in their throne for galactic advancement or see them as a virus spreading in the galaxy. Perhaps that is something we better not discover.
Another one points in the direction of our limited minds. It states that our minds and knowledge might be too limited even to understand what extraterrestrial civilizations are or what they are trying to do. We don’t comprehend their methods or existence or motives. Them contacting us will be like explaining the internet to ants. So they don’t even bother explaining.
Then there is one last possibility. Maybe we are alone in the universe. We have no proof that there is life besides us – we may be completely alone. If this thought sends a chill down your spine, you are in the right mind.
If we don’t save this planet, life may cease to exist in the universe. In that case, we must keep our heads high, venture to become a type 3 civilization and – by taking inspiration from Martin Rees’s words, “The absence of evidence is not evidence of absence” – keep looking for our neighbours.