Chapter 91

John continued, "your father's algorithm is indeed the most outstanding work of mankind, but it is far from powerful enough. Therefore, we can't make the nuclear fusion device smaller. Every reactor is like a mountain. It's too rough. "

Zhang Yuan looked at these turbulence, some bright, some dark, and others rotating, and fell into meditation.

Whether convinced or not, John's complaint is true.

He had a small ambition in his heart, which took root like a seed.

"What my father did, maybe... I can do it too!"

Turbulence is the last mountain in classical physics. About 400 years ago, Navier Stokes equation, that is, N-S equation, has theoretically described the physics of fluid. It is difficult to find the exact solution of this equation, so scientists usually use some simplified theoretical models or resort to numerical simulation to predict the motion of the fluid.

However, it is too inaccurate to use a simplified model to simulate plasma turbulence. If these plasmas are not well constrained, they will cause great damage to the fusion engine.

With the vigorous development of Informatics, there are some looseness in the turbulence problem, but only some looseness, which can simulate more accurately, but can not deeply understand its real essence.

John sighed: "we may never find an accurate mathematical solution to the turbulence problem. Perhaps the complete accuracy is hidden in the more microscopic probability superposition state. We don't know it at all with our ability."

John Wilson is a typical representative of pessimists.

He believes that the upper limit of human science and technology is likely to be like this at present. With human intelligence, we can only turn around in such a small circle.

Although there are still some minor things to be polished, it is impossible to really realize qualitative change.

Therefore, this group of pessimistic scientists want to board the spacecraft and see the world three thousand years later.

This statement is not unreasonable. It took 400 years to completely solve a turbulence problem.

In cutting-edge physics, in addition to the vigorous vitality of condensed matter, everything else has been gradually depressed. High energy physics is plagued by the "energy level desert". Other disciplines, such as chemistry and semiconductors, use some approximate theories. The key is that these approximate theories can indeed solve some problems.

As for mathematics, it is also slowly going downhill.

Riemann conjectures that it will stand for 400 years; Goldbach guessed, 600 years.

The "great unification of mathematics" program is still only a framework, and it is still tens of billions of light-years away from completion.

The new civilization school believes that the present 23rd century, together with the 24th and 25th centuries, is likely to be the last golden age of mankind. Next, the overall human intelligence cannot continue to develop.

Once the development of science and technology stagnates, human civilization is likely to have the phenomenon of historical reincarnation like the ancient Xia state. Using academic words, that is, falling into the "mediocre trap", it is difficult to make great historical progress.

Zhang Yuan actually quite agrees with some views of the new civilization school, but he is neither pessimistic nor optimistic about this issue.

In fact, he doesn't believe that human beings will fall into predictable traps, and it's hard to imagine what the future world will be like. Maybe there will be some technologies to transform intelligence.

In addition, he is more inclined to engineering and technology. Technology and science are still very different. There is still a lot of room for the improvement of human applied technology.

"Zhang, you are too optimistic."

John shrugged his shoulders and said helplessly, "in history, there are many phenomena, such as Latin America, middle-income trap and so on. Even if some countries know it clearly, they still can't cross it, because many things in a country can't be done when leaders realize it. It depends on the strength of the whole. "

"But the collective power of mankind is not as powerful as you think."

"Yes, you're right." "But we have to be optimistic, don't we? Pessimism can't solve any problems. "

After saying goodbye to the sentimental senior brother John, Zhang Yuan returned to his laboratory seat and began to read the literature.

Accidentally turned to a book.

"100000 unsolved mysteries"

From astronomy to geography, from mathematics to physics, there are too many problems that can't be solved. For example, "3x + 1" conjecture, happy ending problem, Gaussian circle problem, Erdos Graham ternary problem... Any one is as difficult as Li guess.

I don't know why. Looking at countless problems, Zhang Yuan always has a slight sense of anger in his heart.

Perhaps, as a member of scientific research workers, I am annoyed by my instinct that I can't completely penetrate nature.

Zhang Yuan secretly squeezed his fist.

At this moment, he finally made up his mind to solve a world-famous problem.

It doesn't matter gain or loss, just follow your heart.

"Turbulence problem!"

"Try it!"

It takes a lot of courage.

It may take a lot of time, nothing can be done, and the sunk cost is huge. Only a young man like him can move forward bravely with his warm blood.

After making up his mind, Zhang Yuan took a long breath and slowly sank his mind.

From the perspective of pure mathematics, there is basically no great possibility.

Zhang Yuan doesn't feel that he can write a more accurate and effective equation than the N-S equation.

"Maybe we can create some informatics methods to solve this problem."

The first method is the famous "spectral method of wavelet transform" used by my father. It is also the best algorithm in engineering application at present. It successfully solves the problem of multi-scale turbulence simulation of engine internal flow in time and space.

In essence, the signal transmission process in neurons is used for reference to describe the burst mechanism of turbulence in pipes.

The second method is the direct numerical solution method.

The isotropic turbulence in a three-dimensional periodic cube is simulated by solving the "N-S equation" of incompressible fluid. However, this method requires high computational force and is suitable for calculating simple turbulent motion with low Reynolds number, such as channel or circular tube turbulence.

Of course, there is a third "RNG" κ-ε Model, the fourth "spalart allmaras turbulence model", the fifth method "internal and external iterative method", and so on.

Human creativity is infinite, but there are only so many meaningful and valuable algorithms.

"Are you looking at turbulence? This thing is not generally complex! "

Zhao Qingfeng glanced at his screen and said with great interest: "I have also studied this content. The core reason is that the problem itself is too difficult. There are no very suitable mathematical tools for the three difficulties: strong nonlinearity, infinite dimensional system and chaotic system."

"So if you want to do it, I don't have any good suggestions for you."

"I know. Just look around." Zhang Yuanlian hurried.

Elder martial brother Zhao smiled and sighed that it was nice to be young. If it were him, he would be far away from this problem.

However, he didn't care too much. There were many things. As long as he understood them, he would retreat.