Are We Alone ?

Our Universe is very vast and mysterious. We don't know whether we humans are the only living species out there or there are also other living organisms out there to whom we call 'aliens'.

“Where is everybody ?” This question was asked by a physicist , Enrico Fermi in 1950.

Probability for Fermi Paradox :

• Recently, we have discovered that there are trillions and trillions of stars and planets around our home galaxy, the Milky Way. So, there is a strong possibility that there will be many living species like us. But, even if that is true, we will never know about that due to our reach because if we have let's say a very advanced spaceship traveling at the speed of light, then too it will take billions of years to reach that part of the universe.

• To know whether life exists outside of our home galaxy is beyond our reach. So if we calculate the probability of the existence of life in our galaxy, then :

1. The Milky way consists of 400 Billion stars, from which 20 Billion are like the sun and an estimate suggests that 1/5th of them ,i.e, 4 Billion are Earth-sized and have their habitable zone(Not too hot and not too cold).

2. If we assume that only 0.1% of those planets have life on them, then we are left with 4 Million such planets.

3. Out of these 4 Million habitats, if we assume that there are only 1% of advanced living lives just like humans, then there would be 40,000 civilizations like us.

4. If we consider that only 1% of such civilizations are capable of traveling through space and explore like us, then there are 400 such civilizations.

• But we have no evidence of their existence. This is the basis of FERMI PARADOX. So, why can't we find them? Here are some possibilities which may be true :

1. We are alone :Maybe there are very complex requirements of any living species to exist on any planet. And out of this GREAT FILTER, Earth is the only favorable habitat that is fulfilling all the complex requirements and so we exist. You can imagine a Great filter as follows :

Till now, we have no evidence of other civilizations who have passed as many filters like that of earth. But, what if we discover other civilizations or aliens in the future. It would be a nightmare for us. The number of planets passing through or surviving the great filter is decreasing in every next filter. So if we discover aliens, then it would be concluded that we are not the 'fittest civilization' among all and there is a strong possibility that we may get eliminated or extinct in the very next filter! So our end will be nearby in such a case.

• Other possibilities :

1. Maybe we lack advanced technology to explore or increase our range in space exploration. If they exist, then why don't they reach us.

2. It might be true that our existence is too small for them just like a grain of sand in the desert.

3. What if their planet is millions of light-years away from us, due to which light of their planet will take a huge time to reach us.

4. Or else their life-span/era is already extinct but the light from their planet(from a time when they were existing) is still traveling in space and it may never reach us because the universe is expanding at an accelerating rate.

• So, Are we alone? No-one knows. None of us knows the direction of our existence. But there is a possibility that your wildest imagination can be true. This is what makes the universe interesting, dark, and sometimes scary too!