The universe is vast, and whether human beings are alone is a question that everyone wants to know. Nowadays, scientists have been looking for alien creatures that are similar to human beings or even more intelligent than human beings, which are often referred to as aliens. If there were really aliens in the universe, where would they be? Why hasn't anyone seen aliens in person yet?

Physicist "Enrique Fermi" proposed a "Fermi Paradox" in 1950, arguing that there may be alien life or alien intelligence in the universe, and this alien life may have advanced technology that humans can't imagine , can travel between the "galaxies" and "interstellar", they may have lived in other galaxies for millions of years. However, so far, the human search for extraterrestrial creatures has not been successful, so what are our chances of finding alien civilizations in the universe?

Since the universe is very old and has many stars, there should be other life outside the earth, unless the origin of life on earth is an unusual process, which may also be called the rare earth hypothesis. People assume that the Earth does not have a unique place in our solar system, and there should be other technological civilizations in our galaxy. Because the width of the galaxy is about 100,000 light-years, it takes up to 1 million years for a sub-light speed spacecraft to travel such a distance, so we can think that the planets they inhabit are too far away to be impossible at the current level of human beings on Earth. find them.

But if it is calculated in another way, for example, it only takes 1 million years for humans to fly to various galaxies in the Milky Way, then aliens can come to Earth as long as they evolve 1 million years earlier than humans. Of course, another theory also exists, it may be that they have not found us, or they have been monitoring humans on Earth. In short, before humans have discovered alien civilizations, the Fermi Paradox will always exist.

Among them, the "Drake equation" is closely related to the "Fermi paradox", and so far, most of the parameters of this equation are still unknown. The Drake equation only deals with the Milky Way, the Milky Way is a barred spiral galaxy, depending on its type, about two-thirds of the existing galaxies in the universe are constructed, as we know the universe now, there are about one hundred billion For a galaxy similar to the Milky Way, the final value from the Drake equation must be multiplied by a relative factor for the entire universe.

According to the results calculated by the Drake formula, there are as many as tens of thousands of planets in the Milky Way alone, and 200 planets may have alien life. Such calculations remain highly imprecise due to insufficient knowledge of other galaxies. In addition, the Drake equation refers not only to the theoretical number of civilizations, but also to the possibility of establishing contact with them. The nearest galaxy to us is the Andromeda galaxy, but it is more than two million light-years away from us. Distance, so we can't contact each other, and we can't know if there is an alien civilization more advanced than us.

There is a paper saying that cellular life in space is very rare, because even the earth and planets are very rare, due to many impossible coincidences, life on earth developed, which would not exist in other planets . These coincidences include the presence of the moon and the position of the Earth in the solar system, which provides the planet with temperatures suitable for life. In this logical interpretation, the parameters of the so-called Drake equation say so. In the galaxy we are in, there is only the existence of human civilization on Earth, so the Fermi Paradox is no longer a paradox, because a basic hypothesis that is more convincing to many scientists has been rejected.

However, there are also scientists who believe that the earth does exist like a planet, especially as more and more exoplanets are discovered, and the fact that interstellar colonization is impossible. The prerequisite for the Fermi Paradox is the ability to colonize the interstellar civilization, but this cannot be achieved in principle, because with this prerequisite, it is possible to have some technological civilization societies. But they can't affect each other, probably because the space is too far apart.

According to Stephen Hawking, the source of life on Earth is likely to be in outer space. He also believes that human beings, like intelligence, will eventually reach their limits and become unstable. These organisms will unintentionally self-destruct, which may be Caused by man-made viruses, nuclear war, or the uncontrollable greenhouse effect. If life on Earth really originated from outer space, then alien civilizations have existed for longer than humans, and they may have inadvertently perished themselves as early as tens of thousands of years ago. After all, there is no absolute definition of life.

There have been several attempts to define life, but none of them are accurate or satisfactory. From this, one can also draw the conclusion that there is no fixed boundary between life and death, even if there is similar life on earth, does this life originate on earth and spread in space, or is it in another place independent of earth A place is born, these still need stronger evidence to clarify. Do you think that humans and the earth are unique in the universe?