There are more than 100 million planets in the Milky Way. Why haven't humans discovered aliens yet?

Some scholars once thought that human beings were actually aliens' immigrants. In ancient times, aliens from another galaxy came to the solar system. At that time, many aliens went to the earth to mine, but they failed halfway. Their temporary base, Planet X, also exploded about 700,000 years ago and the starship was destroyed. These aliens could not return to their home planet, and finally chose to stay on the earth. After generations of reproduction and evolution, it has become a modern human being, which is one of the reasons why human beings are still incompatible with the earth in many aspects.

Although this statement seems absurd, there are still many people who believe in the existence of aliens, and alien civilization has been lurking in the universe. Since modern times, especially in recent years, human science and technology have developed faster and faster. Some scientists have done statistics, and there are at least hundreds of millions of planets in the universe with alien life, but we haven't found it yet. According to what we know today, it is very inaccurate for us to easily deny the existence of alien life.

So, how did this data come about? Take the Milky Way as an example. There are at least 654.38+00 billion stars in the Milky Way, but in the universe, there are about 654.38+00 billion stars similar to the Milky Way. Even if the probability of life is 654.38+0/654.38+0,000,000,000,000,000, there are at least hundreds of millions of planets with life. How should humans look for it? In fact, as early as 200 years ago, human beings had tried to contact with alien civilizations, and in the 1970s, human beings officially sent radio waves to the universe. If a planet with alien civilization is within 70 light-years from the Earth, it is very likely that they have received the signal sent by human beings and have returned to the Earth, but they have not returned to the Earth.