The earth has lived in the universe for hundreds of millions of years, while human beings have only lived on the earth for tens of millions of years. Since ancient times, people have looked up at the starry sky and thought about several questions: where do we come from, where are we going, and where is our destination?
Since the first batch of African ancients went out of Africa and went to various continents, their first consideration was how to survive. When they solved the problem of food, clothing, housing and transportation and entered the industrial age, they began to think about a question: how big is the universe? So they invented the astronomical telescope and began to observe the vast universe outside the earth.
Because of insufficient observation, they invented the detector and flew to the moon, but when they looked at the earth on the moon, their world view changed greatly: it turned out that in the universe, human beings were not even bugs. Entering the atomic age and the information age, they studied the structure of the universe and found that the sun was formed by the continuous collapse of many energies and atoms. In China's fairy tales, our Houyi was very competent, shooting off nine redundant suns, leaving only one sun, making the earth have sunrises and sunsets every day all year round, forming an eternal era.
What exactly is a constant era? When our planet moves steadily around one of the suns, it is the eternal era; When one or two other suns run within a certain distance, its gravity will take the planet away from the sun around it and make its three suns wander within the gravitational range, which is the chaotic era; After an uncertain period of time, our planet was once again captured by a sun, temporarily establishing a stable orbit, and the eternal era began again. Because we only have one sun, there is no eternal era and chaotic era, and the three-body world in science fiction is sometimes a long night and sometimes a long day.
The universe is a dark forest, and every civilization is a hunter with a gun, sneaking in the forest like a ghost, gently peeling off the branches in the way, trying not to make a sound, and even breathing carefully; He must be careful, because the forest is full of sneaky hunters like him. If he finds other life, there is only one thing he can do: shoot it. In this forest, others are hell and an eternal threat, and any life that exposes its existence will soon be destroyed. This is the basic picture of cosmic civilization, and this is the explanation of Fermi's paradox.
There is a saying in "Three-body": The dried-up fish go ashore before the dried-up sea, and they run from one dark forest to another. Here, the universe is compared to a dark forest, and every civilization may be destroyed at any time. This is a race with death, and death is only to make people walk on the road better.