178.

The problem of the 2000th layer is also a very classic mathematical problem, although this problem, purely in terms of the importance of the mathematical system, is not as epoch-making as calculus.

But it played a pivotal role in the history of mathematics and even physics in the 19th century.

Some even call it the most spectacular triumph of mathematical physics of the 19th century!

In fact, when Cheng Li answered the question of the 1999th floor, he had a hunch that the 2000th floor would be this problem.

Because the 1999th layer problem is a problem about partial differential equations.

This question comes from "The Analytic Theory of Heat" by the French mathematician Fourier.

The Analytic Theory of Heat is also one of the classic texts in the history of mathematics, and the final answer to the 1999th layer problem is the famous "Fourier series".

The Fourier series opened the prelude to the development of partial differential equations in the nineteenth century, and then gave birth to a new discipline called "mathematical physics".

It was also in the nineteenth century that mathematics really became the engine for the development of all other scientific disciplines, and mathematics began to develop at an astonishing rate and be applied everywhere.

Even when some mathematical theories are proposed, even the creators of the theories themselves do not know what use they can have, but after a few decades or even hundreds of years, people will find that the original mathematical theory can be applied in this place or in that place.

So some people even say that no mathematical tool is useless, and if there is, then people just don't know how to use it.

The partial differential equations represented by the Fourier series opened such an era of great application of mathematics.

After the Fourier series, on this basis, a more famous partial differential equation is one of the most classic examples of the era of such great applications of mathematics.

That is the system of electromagnetic field equations, also known as Maxwell's equations.

That's right, the question of layer 2000 is about the system of electromagnetic field equations.

At this time, suspended in front of Cheng Li's eyes, the problem of combining the light words is also very simple to display.

"Q, how do you derive the equations for electromagnetic fields?"

Cheng Lixin said: "Sure enough, this is the topic. ”

However, for Cheng Li, the last thing he is afraid of is to ask some classic questions, but he is more afraid of those more out-of-the-way and very obscure topics. Therefore, for Cheng Li who has already learned the derivation process, although it is not easy to deduce it again independently, it is still within the scope of Cheng Li's ability.

Therefore, Cheng Li just sorted out his thoughts a little in his heart, and began to write and draw on the light spot, and wrote down the derivation process of Maxwell's equations.

This is also due to the fact that after Cheng Li became a cultivator, his memory became stronger and stronger, and he even deepened his memories of the books he had read before.

Otherwise, if it was before becoming a cultivator, it would be really difficult for Cheng Li to write down such a complex derivation process directly in one go.

Cheng Li wrote, and he was extremely emotional in his heart, Maxwell's equations, that incomparable beauty.

Cheng Li hadn't felt so profound before, but at this moment, nourished by the silent information of the arithmetic tablet, Cheng Li understood Maxwell's equations more deeply than before.

This also made Cheng Li feel more and more the greatness of Maxwell's equations.

Maxwell's equations are considered to be the most spectacular triumph of mathematical physics in the 19th century, mainly because Maxwell predicted the existence of electromagnetic waves from this equation.

And later, according to Maxwell's equations, such a purely mathematical formula, one famous physical theory after another was derived.

And these physical theories, in scientific experiments decades later, or even hundreds of years later, were verified one by one, and the accuracy of Maxwell's equations was perfectly confirmed.

This made people realize for the first time that pure mathematical formulas can contain such profound objective physical laws.

It is no wonder that some people exclaim that if the truth of the universe is written in a certain language, then that language must be mathematics.

It is no wonder that Marx once said that a science can only be considered to be truly perfect when mathematics is successfully applied.

Therefore, it is only reasonable that Maxwell's equations will be used for this important level problem of the 2000th layer.

The derivation process of Maxwell's equations is still relatively complex, involving the calculation of many partial differential equations.

It took Cheng Li a full ten minutes to finally write the entire derivation process and the light curtain full.

However, the moment Cheng Li finished writing, the entire point of light floated again, and finally the two big words "correct" appeared.

Cheng Li breathed a sigh of relief at this time, he felt that he was a little out of strength, and his forehead was sweating profusely.

So he sat directly on the ground and wiped the sweat from his forehead.

Sometimes, mental activity is more tiring than physical activity, and Cheng Li feels a little dizzy. You must know that he is now a cultivator's physique.

"What time is it? ”

Cheng Li closed his eyes, and he didn't have the strength to look at the time displayed in the lower right corner of the light curtain.

"It's 9:50 a.m. ”

The figure of the little arithmetic boy "snapped", and he appeared beside Cheng Li out of thin air and replied.

"...... at 9:50"

Cheng Li recalled that he began to enter the 1001st floor at 2:26.

Then it took him 1 hour to reach the 1500th floor.

However, it took more than 6 hours to reach the 1,500th floor to the 2,000th floor.

The 500 floors behind this can be imagined.

The further back the layers, the gold content and difficulty of each layer are higher and higher than the previous layers.

At this time, Cheng Li is equivalent to doing 9 hours of high-intensity test papers in a row, and if he doesn't take a break, he has to put ordinary people aside, and it is estimated that he will be tired and hanged up a long time ago, but fortunately, Cheng Li is now a cultivator's physique, and he can barely bear it.

"You're really useless. Xiao Shutong said disdainfully.

Cheng Li replied directly after relieving himself: "It's not you who do the question, of course you don't care." ”

"Cut, I'll be good on these topics, I'm a machine spirit of the Monument!"

"Well, you have a good point, I can't contradict you. Cheng Li was speechless for a while.

"Cut, you're lucky. These 2000 layers happen to have a reward mechanism. Xiao Shutong felt that it was almost too much to flirt with Cheng Li, so he threw out the reward.

"Oh, there is a reward?" As soon as Cheng Li heard the word reward, the whole person suddenly became energetic, his head was not dizzy, and he did not feel tired, and suddenly looked at the little arithmetic boy with his eyes.

"Then this reward, do I need to choose to go to the Yin-Yang Arithmetic Inheritance in order to obtain it?"

"No, this reward is an additional reward, whether you choose the path to the Yin-Yang Arithmetic Inheritance next, or choose to continue to challenge the trial, you can get this reward!"