However, 380,000 years after the Big Bang, the universe gradually "cleared up" and photons were able to travel through the universe. Later, hydrogen collapsed into the first generation of stars under the action of gravity. After a long time, the first generation of stars ushered in the end of life, so in the supernova explosion, the heavy elements in the core area of the star were spread into space.

The sun was born in the debris nebula after the supernova explosion of the first generation of stars, so the sun contains 2% heavy elements, and other heavy elements in the solar system constitute planets and life, so the astronomical community thinks that heavy elements are the "mother of life"

There is nothing special about the solar system itself, because a large number of second-generation stars in the universe contain heavy elements, and most of them have one or two planets, so the planet earth in the livable zone must exist in the universe, and the process similar to the origin of life on earth also exists in the universe with a high probability.

Based on the vastness of the universe and the numerous stars, the scientific community generally believes that the earth and human beings are not special in the universe.

Then, under special circumstances, today, tens of billions of years after the birth of the universe, why isn't there a civilization whose sphere of influence is all over the universe?

The answer lies in the laws of the universe itself.

"The speed of information transmission cannot exceed the speed of light" in the law of the universe determines that no civilization can expand excessively, because the result of expansion is that information lags behind. Imagine a civilization with a territory of thousands of light years, and the communication speed between them is still slow at the speed of light. How can we further expand?

Therefore, the law of the universe itself is the biggest constraint on the expansion and development of cosmic civilization. No matter the electromagnetic waves that humans are using now, or neutrinos and gravitational waves that are still in the sci-fi stage, the transmission speed of these communication media cannot exceed the speed of light. So in the universe hundreds of thousands of light years away, there is not much room for the development of intelligent civilization.

Humans have not discovered alien civilization, which is only temporary.