Today’s earth has only human intelligence civilization, but the earth has a long life history of 4 billion years. In such a long time, is it true that only human civilization has ever appeared on the earth? You know, it’s only a few million years since humans evolved from the ancient ape.
Millions of time has created today’s human science and technology civilization, so the life history of 4 billion is thousands of times of human evolution time. If there is a cycle of civilization every few hundred million years, there may be more than ten civilizations on earth. Of course, this is just a kind of random conjecture. Whether prehistoric civilization existed or not has not been confirmed yet.
After human beings walk out of the earth, there should be many interstellar civilizations that are much stronger than human beings from the perspective of the vastness and time of the universe. The universe should be very lively, but the real result is that we see a quiet and lonely space.
Since there are many intelligent civilizations in the universe, which are very lively, why are they so lonely now? Some people speculate that the universe in the past may indeed be very lively. There are many intelligent civilizations, but these intelligent civilizations have disappeared in all kinds of disasters.
If the alien civilization in the universe can not develop forever, and will disappear in the process of civilization development, then human beings may also have such a day in the future. So a friend put forward such a question: if human beings disappear one day, will the newly born civilization know that human beings once existed?
Countless years after the extinction of mankind, a new intelligent civilization has emerged on the earth. In the eyes of the new intelligent civilization, we are prehistoric civilization. Can they know that human beings once existed? Perhaps the new wisdom civilization will also guess that there may have been other wisdom civilizations in the long life history of the earth.
How can we prove that human beings once existed? At this time, we need to find all traces of human existence. Some people may say that time is a merciless knife, it will erase all traces of human existence, is this really the case?
There is nothing wrong with the fact that time can erase the traces of civilization, and as time goes on, the cleaner it will be. However, no matter how powerful the years are, it is impossible for a human civilization to completely erase the traces of science and technology. There will always be some clues.
If human civilization is extinct before entering the era of science and technology, then after hundreds of millions of years, nothing will be left and all traces will be erased. But as early as hundreds of years ago, human beings embarked on the road of scientific development. The emergence of science and technology will make many things unusual.
If a new intelligent civilization is born after tens of millions of years after the disappearance of human beings, then the traces of human existence can be easily found. We all know that 65 million years ago, before the birth of mankind, there was also a glorious era of hegemony. At that time, dinosaurs were dominating the earth. They spread all over the earth, and the number of races was also very large, accounting for more than 80% of the earth’s creatures at that time.
Later, an asteroid with a diameter of 10 kilometers hit the earth, causing ecological upheaval, which led to the extinction of dinosaurs on the earth. Now 65 million years later, scientists found a large number of dinosaur fossils all over the world, only to know the glorious age of dinosaurs.
In 65 million years, although years have erased the traces of dinosaurs, those fossils can not be erased. Through dinosaur fossils, scientists can see the prosperity of dinosaurs at that time. In the same way, human beings are now the overlord of the earth, and they are all over the world, and the number is also very large.
If human beings disappear because of a disaster, many human fossils can be preserved after tens of millions of years. The newly born wisdom civilization, through these human fossils, will know that before they appeared, there was a brilliant human civilization on the earth.
But what if the emergence of the new wisdom civilization is hundreds of millions of years later? Will there be traces of human existence? If the time span reaches hundreds of millions of years, the fossil traces of human existence may also be erased by time. Even if some remains are left, they are probably deep underground, and are not easy to be discovered by new civilizations.
If the time reaches hundreds of millions of years, the only traces that can prove the existence of human beings on earth may be nuclear reactors. As we all know, with the development of human science and technology, the most powerful energy source is nuclear energy, and the raw material of nuclear energy is uranium. As long as we use uranium, it will leave a long trail.
The reason is that the half-life of uranium is very long, basically hundreds of millions of years or more. In Africa, scientists once discovered a natural nuclear reactor. At that time, scientists mistakenly thought that it was evidence of the existence of a prehistoric civilization. However, later studies found that it was a natural nuclear reactor, which had existed for 2 billion years.
The reason why scientists can find this natural nuclear fusion reactor is based on the half-life of uranium. It can be seen that as long as uranium has been used, it will leave long traces. However, there is a huge gap between natural nuclear reactors and man-made reactors in terms of energy level, so after the disappearance of human beings, the used nuclear reactors will still leave very obvious traces even after hundreds of millions of years.
As long as the new intelligent civilization can discover the nuclear reactors used by human beings, it can prove that human beings once existed through the half-life of uranium. In addition to the traces of human civilization on earth, there will also be traces of human exploration in space and other planets.
Compared with the environment of the earth, the space environment and the environment of some other planets are more conducive to the long-term preservation of traces. Space is an environment close to vacuum, and human science and technology products can be preserved for a long time after they arrive in space. If the new intelligent civilization also enters the era of science and technology and goes out of the earth, it will be able to see the space garbage and know the glory of mankind.
In addition, our probe to other planets, the use of energy also has nuclear energy, such as Mars probe curiosity, its energy is nuclear energy. As we have said before, nuclear energy can leave traces even after hundreds of millions of years. Therefore, once a new intelligent civilization starts to explore Mars, it may also be able to find traces of human existence on Mars.
The stronger the scientific and technological strength of civilization, the longer the things left will be preserved. If we reach the second level of civilization, we will have the strength to build the Dyson sphere. This kind of magnificent man-made building enveloping the stars will leave very obvious traces even if the civilization has disappeared for hundreds of millions of years.
And there may be many traces of such a powerful civilization in the universe. As we said earlier, the reason why human beings can’t find alien civilization may be that alien civilization has disappeared. If an interstellar civilization is extinct due to disaster, there will be many traces of civilization in the parent galaxy where they live. As long as we can find such traces, it is of great significance to human beings.
Of course, to search for the remains of alien civilization, we need to go to other galaxies, and to achieve this ability, our spacecraft must at least achieve sub light speed. This speed is still too far away for human beings, and we don’t know when human beings will have the hope to realize the interstellar navigation.