Are we the only living thing in the entire universe? The observable universe is about 90,000,000,000 light years in diameter. There are at least 1,000,000,000 galaxies each with 100,000,000,000 to 1,000,000,000,000 stars. Recently we have learned that planets are very common too and there are probably trillions and trillions of habitable planets in the universe. Which means there should be lot of opportunities for life to develop and exist, right? But where is it? Shouldn’t the universe be teeming with spaceships? Let’s take a step back.
Milky Way:
Even if there are alien civilizations in other galaxies, there is no way we will ever know about them. Basically everything outside of our direct galactic neighborhood, the so called ‘local group’ is pretty much out of our reach forever, because of the expansion of the universe. Even if we had really fast spaceships it would literally take billions of years to reach these places, traveling through the emptiest areas in the universe. So let’s focus on the Milky Way. The Milky Way is our own galaxy; it consists of up top 4 hundred billions stars. There are about 20 billion sun-like stars in the Milky Way and estimates suggest that a fifth of them have an earth-sized planet in its habitable zone, the area with conditions that enable life to exist. If only .1% of those planets harbored life, there would be 1 million planets with life in the Milky Way.
Civilizations:
The Milky Way is about 13 billion years old. In the beginning, it would not have been a good place for life because things exploded a lot, but after 1 to 2 billion years, the first habitable planets were born. Earth is only 4 billion years old, so there have been probably been trillions of chances for life to develop on other planets in the past. If only a single one of them had developed into a space travelling super civilization we would have noticed by now. What would such a civilization look like? There are three categories. A-type civilization would be able to access the whole energy available on its planet. In case you are wondering, we are actually around .73% on the scale and we should reach type 1 sometime in the couple hundred of years. Type 2 will be a civilization capable of harnessing all of the energy of its home star. Type 3 is the civilization that basically controls its whole galaxy and its energy, an alien race this advanced would probably be godlike to us. If we were to build generations of spaceships that could sustain a population for around one thousand years, we could colonize the galaxy in 2 million years. Sounds like a long time but remember, the Milky Way is huge. So, if it takes couple of million years to colonize the entire galaxy and there are possibly millions if not billions of planets that sustain life in the Milky Way and these other life forms have had considerably more time than we’ve had, then where are all the aliens? This is the Fermi Paradox and nobody has an answer to it but we do have some ideas.
Filters:
Let’s talk about Filters. A Filter in this context represents a barrier that is really hard for life to overcome. They come in various degrees of scary. One: there are great Filters and we’ve passed them. Maybe it is way harder for complex life to develop than we think. Maybe in the past the universe was way more hostile, and only recently things have cooled down to make complex life possible this would also mean that we may be unique, or at least one of the first, if not the first civilization. Two- there are great Filters and they are ahead of us. This one would be really bad. Maybe life on our level exists everywhere in the universe. But it gets destroyed when it reaches a certain point, a point that lies ahead of us. For example, awesome technology exists, but when activated it destroys the planet. If this is true then we are close to the end than to the beginning of human existence. Or maybe there is an ancient type 3 civilization that monitors the universe and once the civilization is advanced enough it gets eliminated in an instant. Maybe there is something out there that it would be better not to discover. One final thought, maybe we are alone. Right now, we have no evidence that there’s any life besides us. If we let life on this planet die, perhaps there will be no life left in the universe. Life would be gone, maybe forever. If this is the case, we just have to venture to the stars and become the first type 3 civilization to keep the delicate flame of life existing and to spread it until the universe breathes its final breath.
Transcripted By Benazir Elahee Munni
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