On the possibility of human beings doing interplanetary navigation

In science fiction movies, we often see a variety of spaceships carrying humans swimming in the ocean of stars. But all fantasies—even science fantasies—are just fantasy. At least for the foreseeable future, this ability to fly freely between the stars is not something that we humans can have. There are many problems that we need to solve.

The first problem to solve for long-distance navigation is the distant distance. In the 茫茫 universe, the commonly used meters, kilometers and other length units can only be regarded as a drop in the ocean. The distance from the Earth to the Sun alone is 150 million kilometers. Therefore, people often use light years and second gaps to measure the distance in the universe. A light year is about 690 billion petabytes, and the one-second gap is equal to 3.85 light years. But the unit of length in light years is still too small. Because we have observed the farthest celestial body from the Earth, we have 14 billion light years away. If you convert to a kilometer, you need to use 9.6 trillion by 14 billion, in kilometers, and the result is a long list of dizzying numbers. Therefore, the distant distance has become the first obstacle for human beings to achieve space navigation.

The second problem is speed. Liquid and oxygen are commonly used in the fuels of spacecraft. The fastest speed can reach the third universe. This speed is enough to complete the flight within the Milky Way. But if you want to fly out of the galaxy and explore a broader space, you need to reach the fourth cosmic speed. If you calculate according to the maximum speed of the existing spacecraft, it will take 9 months to fly to Mars and 7 years to Saturn. Scientists are trying to design a light-speed spacecraft, but it takes more than a year for such a spacecraft to fly to the nearest star, the neighboring star of Centaurus. According to the general theory of relativity proposed by Einstein: the speed of light is the limit of speed in the universe, and it can be infinitely close, but it cannot be surpassed. Therefore, there are still many technical problems that need to be solved to create a light speed spacecraft. Moreover, even if we have a light speed spacecraft, it is impossible to fly between galaxies that are tens of hundreds of light years away. From some perspectives, flying between the stars is just an impossible dream for human beings. This may mean you may be disappointed, but this is the law of nature.

The third problem is the high risk and the strong loneliness of the astronauts. In the universe, any star is using its own gravitation to change the surrounding environment. A gravitational celestial body can even change time and space. The temperature in the universe can range from a few hundred to several tens of millions of degrees, down to near absolute zero. There are also four wandering meteors, as long as a fist-sized meteor hits the spacecraft bulkhead, at high speeds, local pressure can reach tens of thousands of megapascals, which is enough to cause the ship to die. All of this is threatening the safety of astronauts.

The time of a long journey is very boring. The earth is just a shadow, and the audio phone will take more than ten minutes to receive the information on the earth. In the case of weightlessness and low pressure, the blood may boil and the heart may stop beating in an instant. Some astronauts once said; 'If you keep two people in the same cabin for a month, you can satisfy all the conditions of the killing. '

With the continuous advancement of science and technology, the deep seas of the mountains have bowed their heads, and the lightning and thunder are no longer mysterious. Humans have turned their eyes to space. However, there is still a long way to go before human beings can explore more far-reaching space. Perhaps this is a eternal dream for mankind.

The second middle school of Duyun, Guizhou, the second day: exhibition Yang Lan