There are many science fiction movies, books, and video games about aliens. We dream about a universe full of species and spaceships interacting with each other. The universe is so big that there should be thousands of civilizations in the universe. However, we do not see any concrete proof of intelligence living in space. Where are the aliens? This is the Fermi Paradox, the high probability of the existence of aliens and the emptiness of the space.
There are 20,000,000,000 stars in our galaxy that have a size similar to the Milky Way. 20% of them have a planet with a size similar to the Earth that is located in a habitable zone, not too far from its sun and not too close. These planets have the capability to develop life. There should be 1,000,000 planets with life in the Milky Way.
Many of those planets had a lot more time than the Earth to develop their life. The Milky Way is thirteen billion years old. The formation of the planets and the solar systems took two billion years. That lives those planets with 11 billion years to develop intelligent life until it becomes a super civilization with the power of traveling through the universe. Our planet is only 4 billion years old.
To become a super civilization, inhabitants of a planet would have to fully control all resources from its planet. Humanity is trying to achieve this with our every time more advanced technology. Then, they would have to control all the energy from its sun. That amount of energy would allow them to travel to very far places and populate the planets controlling the galaxy and its resources.
Due to these factors, there should be millions of planets in the universe with intelligent life, and spaceships traveling all directions. Nobody knows why the universe is so empty, but there are theories that try to explain this problem.
Theory one: It is more difficult than we think for life to start on a planet. For example, maybe there must be very specific chemicals that have to be combined in a very specific way to start live. Maybe the universe was more chaotic than we think, and the Earth is one of the first planets to finish its development. In this case, we would be the first or the only civilization in the universe. Maybe our existence is a miracle that has very few probabilities to occur.
Theory two: There are some obstacles that destroy every civilization when it is developing. Climate change and nuclear war would be the causes of the destruction of all civilizations. Another more imaginative obstacle would be a galactic empire that destroys every planet when its inhabitants reach a high level of intelligence. In either case, we would be very close to being destroyed or to destroy ourselves.
What do you think? Are we alone in the universe or is there some kind of intelligent life somewhere? Will we destroy ourselves living the universe dead and dark? In my opinion, we may do it someday.