The entire human development process can be summarized into three words, that is, "going out".
The reason why human civilization can continue to improve is because humans always try to expand their activity areas. Now, humans have basically traveled all over the earth, so we have turned our attention to the farther universe. If you want to "go out", you must have corresponding means of transportation. To leave the mountain village and go to the city, we need a carriage, and to shuttle between provinces and cities, cars are essential. If you want to cross the ocean and travel back and forth between countries, you have to rely on airplanes. Then, if we want to leave the solar system and look at the outer space, what should we rely on? Spaceship, so what is the power of the spaceship? Chemical combustion? This certainly won't work.
We can now leave the earth and go to the universe, but we can't go too far, precisely because the human aerospace industry is still in the chemical fuel stage.
The energy that chemical fuel can produce is extremely limited, so to get rid of the earth's gravity, you need to carry a large amount of fuel, so there are very few things that can be transported to the sky, so even the fuel used to slow down when the spacecraft returns, so we can only return to the free fall , so that the return capsule is violently rubbed with the atmosphere. This method is actually dangerous. It can be seen that it is simply impossible to use chemical fuel to leave the solar system. To leave the solar system, we must rely on new energy. As of now, there is only one new energy that can lead humans out of the solar system, controllable nuclear fusion .
In science fiction works, there seem to be many future powers that can be applied to spacecraft, such as curvature flight, antimatter engine, etc., but these distances are too far away, and the only thing that can be seen and touched is controllable nuclear fusion.
Humans used the principle of nuclear fusion to create hydrogen bomb . The energy that nuclear reaction can release is undoubtedly amazing, but it is not that simple to make it controllable. In terms of technical difficulty, controlled nuclear fusion and controlled nuclear fission are not at the same level, because the temperature required for nuclear fusion is too high. The sun is a huge fusion reactor, but the sun is a star, and its huge mass gives it huge pressure, so it only takes 15 million degrees to trigger hydrogen nuclear fusion. It is impossible to simulate the huge internal pressure of the sun on the earth.
We cannot simulate the huge pressure inside the sun, so we can only work hard on the temperature.
You may know that to detonate a hydrogen bomb, you must use atomic bomb as the guide, because only the high temperature of hundreds of millions of degrees generated by the atomic bomb explosion can successfully trigger nuclear fusion. It is easy to detonate a hydrogen bomb, but it is difficult to slowly release the energy of nuclear fusion. It is not difficult to create a high temperature of 50 million to 100 million degrees, but it is not so simple to keep the temperature within a stable range. Even if it is maintained, no known substance can withstand such a high temperature. Therefore, it is not possible to let the fusion reaction substances come into contact with any substance, and they must be constrained by magnetic field and inertia. When it comes to magnetic field constraints, humans still have a certain foundation.
As early as the 1950s, humans created an magnetic constrained device called the tokamak device.
Tokamak device is an annular vacuum chamber where a coil is wound around the vacuum chamber. After powering up, the coil will generate a huge spiral magnetic field, heat and facilitate fusion reactions, and can also constrain high-temperature plasma to prevent it from contacting any substance. At present, the research on controlled nuclear fusion magnetic constraints conducted by humans are based on the Tokamak device. Although some companies have taken other ways and claimed to have made certain progress, since the specific principles have not been announced, we cannot judge whether it is true or not.Compared with magnetic constraints, the progress in the direction of inertial constraints is relatively slow, but some people believe that inertial constraints are more suitable for future spacecraft.
The fuel required for controlled nuclear fusion is extremely easy to obtain. The principle is that light atoms will lose mass during the process of fusion into heavy atoms, and the mass of these lost mass will be released in the form of energy.
According to the mass-energy equation of , it can be seen that slight mass loss can generate huge energy, so it only takes a small amount of fuel to meet long-term interstellar navigation, which is the best choice for spacecraft. More importantly, relying on controlled nuclear fusion, we can achieve 1% light speed flight, and there is room for improvement. If we calculate based on the radius of the solar system of one light year, we can fly out in just 100 years, and we can reach the Proxima , the closest to the solar system, in 400 years. There is no doubt that the application potential of controlled nuclear fusion is unlimited, so even if a lot of manpower and material resources are consumed, the enthusiasm of various countries for research on controlled nuclear fusion has not diminished at all.
