"Corpse" said: The four directions up and down the universe, the ancient and the present known as the universe. In a very ancient era, human beings began to have a huge interest in the time and space in which they grew, and with the development of modern human science, the exploration of the universe has become more frequent. However, the more profoundly we explore the universe, the more we discover the shallowness of our understanding of the world.
In ancient times, many of us thought that the world was the earth, or even a certain place on the earth, which led to the European geocentric theory and heliocentric theory. However, with the deepening of our exploration, we have discovered more and more the vastness and mystery of the universe, such as the size of the universe, which we now generally think of as a existence with a diameter of 160 billion light-years, such a large diameter, I am afraid that we humans will spend our lives and it will be difficult to walk on one of them in one hundred billionth.
This is the scale of cosmic space, as for the scale of cosmic time, it is now generally believed that the age of the universe is 13.82 billion years, as for the negative number of the timeline, does the universe exist? No one can say anything about such a question now. It is precisely because of the vastness of the universe that many of us are wondering whether such a large universe is only a highly intelligent creature like human beings? Is there only one living planet like Earth?
Even people without any scientific experience, just by intuition, will not be like this. Because infinite space and time mean infinite possibilities, then the probability and quantity of life in the universe should also be close to infinity. In the vast universe, there cannot be only one "lone traveler" for human beings. However, despite the repeated occurrence of "alien" incidents, very few have really definitive evidence.
Since 1949, the mainland's science and technology have developed rapidly, especially aerospace science, which has advanced by leaps and bounds like rockets. This has also led to the rapid development of Chinese exploration in space, and Yang Liwei is a witness to this huge progress. He went into space in 2003 and gave us a lot of more direct experiences about space. Yang Liwei once heard a "knock on the door" on the spaceship, and the truth was revealed 17 years later, thanks to his timely return.
Yang Liwei was originally an Air Force pilot and successfully flew in the Air Force for 1350 hours. It is precisely because he has a very rich flight experience and has experienced many unexpected events in flight, so he was selected as a reserve astronaut in 1997 and began to prepare for space navigation Chinese. In July 2003, after a long period of training, he was identified as a third-level astronaut and prepared for the "flying" mission.
At 9 o'clock on October 15, under the attention of everyone at home and abroad, the former pilot, as an astronaut, represented Chinese in the Shenzhou 5 spacecraft carried by the Long March 2 to charge into space, which was the first time that the Chinese embarked on a space journey, which invigorated countless Chinese and made countless foreigners feel sincere admiration for the progress of China, a rising star in aerospace.
However, behind the success there were countless hardships and accidents, which were not known to most people at that time. Yang Liwei once encountered a very strange encounter in space: he heard a knock at the door inside the spacecraft. At that time, as the first Chinese to enter space, all kinds of domestic information on space were scarce, and foreign information was the "secret" of others, so he could only rely on his own temporary decisions on emergencies in space.
He, who had a very high psychological quality, was still a mental shock when he heard this knocking on the door: What is the situation? He had two options, either to go and see who was knocking on the door, or to go straight back to Earth. Considering that the space environment is extremely complex, and this knock on the door is from outside the spacecraft, he immediately chose to return after reacting to the ground command center.
It is certain that there were no astronauts from other countries near Yang Liwei's spacecraft at that time, so who was "knocking" on the outside of the spacecraft? Could it be aliens? After Yang Liwei returned to the trip, he specifically reflected to the relevant personnel on this matter, and everyone was nervous about this matter, and even did not let this news spread everywhere. After spending a lot of time and energy studying for 17 years, a scholar finally came out and pointed out the truth of the "knocking" outside the spacecraft: it was the problem of the spacecraft.
There are many cosmic rays in space, and the destructive effect on various materials is relatively large. At the same time, because there is no air here, the spacecraft must maintain a certain air pressure, so the spacecraft also has to withstand a huge air pressure squeeze. In addition, the temperature difference between day and night here is huge, the material is extremely expanded when the temperature is high, and the material is extremely contracted when the temperature is low, so the material of the spacecraft is under great pressure during the voyage.
The "knocking sound" of the spacecraft is that the spacecraft material is deforming, and the sharp deformation makes the spacecraft make a sound. Fortunately, Yang Liwei returned in time, but the consequences were unimaginable, because the United States had a similar accident on the Apollo 13 in 1970, and the spacecraft exploded. Although the knock on the door proved that it was not an alien, people's exploration of aliens did not stop there, and I hope that more discoveries will be made in the future!