Scholar’s Advanced Technological System

time flies.

On April 20, Academician Lu returned from Shanghai to Jinda for a meeting. After the meeting, Lu Zhou was sent to the office.

As soon as Lu Zhou entered the door, the old man came over and asked with a smile.

"How are you preparing?"

Lu Zhou: "It's almost over, I hope Professor Professor will show mercy."

Academician Lu: "Almost there? Let's do that, I'll just take your two questions."

Then, he opened the drawer, pulled out an a4 sheet of paper, and put it on the table.

"Pen is here, write it down?"

Lu Zhou took the pen and paper, glanced at the problem above, and frowned fiercely.

Say good two questions, three clearly written on the paper.

And if you say yes, you can take the test casually.

Academician Lu asked with a smile: "Why, I don't understand?"

"How come," Lu Zhou smiled, looking at the subject, a thoughtful expression appeared on his face, "It just looks like it's not easy."

Academician Lu smiled and didn't speak, raised Erlang's legs, waiting for him to write.

Not easy?

If this is easy, what else does it mean?

How can he say that he is also an academician. Can the graduate students brought by academicians be the same as graduate students brought by ordinary professors?

These questions were not originally for graduate students, but they were used to examine the professional knowledge of those interviewers when he recruited doctoral students.

If two questions can be done, then it is qualified. If three questions can be done, it can be said to be excellent.

The four PhD students he brought with him were all capable of solving three questions. Although the topics examined are different, the levels are similar.

While Academician Lu was waiting for his landing boat to write, Lu Zhou had quickly passed all three questions, and then looked at the first question, which was also the easiest question for him.

The first question is about group theory.

However, it is not the mathematical group theory that is examined, but the application of group theory in quantum mechanics.

Because the group theory of mathematics was created independently by mathematicians long before the advent of "quantum mechanics", unlike "calculus", which was co-founded by physicists and mathematicians. Therefore, group theory is an "exotic product" for physics workers. It is difficult to learn and not easy to use.

But for Lu Zhou, who was born with mathematics and reentered into mathematical physics, it was not so difficult to handle.

Group theory explanation of accidental degeneracy of hydrogen atom energy levels

The title is short, but the amount of information is not small.

The phenomenon that hydrogen atoms degenerate more than ordinary atoms is called "accidental degeneration". However, traditional quantum mechanics cannot explain the phenomenon of accidental degeneration, and it was not until the introduction of group theory that this phenomenon was theoretically explained.

Closing his eyes, Lu Zhou remembered the quantum mechanics knowledge he had learned before, and remembered everything about the hydrogen atom.

Then, mathematically build the model

Opening his eyes, Lu Zhou took a deep breath, finally took the pen and wrote on the paper.

Let the hydrogen atom Hamiltonian be hp2 / 2ze2 / r

In the case of Coulomb potential, there is a Runge Lenz vector in the system, denoted as m ’

Eigenvalues ​​of the group casimir operator c

Seeing the speed of Lu Zhou's work, Academician Lu's eyebrows were raised slightly.

He originally thought that Lu Zhou had to spend at least twenty minutes to think about this question, but he did not expect that he had already written.

Moreover, the idea is completely correct.

He originally planned to raise his mouth when Lu Zhou couldn't think of it, but now it seems that it is not necessary.

For the energy level e (n + 1) and the quantum number (n, 1), the degree of degeneracy is Σ2 (l + 1) n2

Seeing the answer, Academician Lu nodded silently.

First question, correct!

Without paying attention to the expression on Academician Lu's face, Lu Zhou continued to focus on the next question.

The second question is about Dirac's hole theory in quantum field theory. It examines the understanding of Dirac's equation and some theoretical knowledge about field theory.

This kind of pure theoretical knowledge is not difficult for Lu Zhou. Under the state of drug-guided concentration, he will not forget what he sees.

For him, compared to the first question, which takes a little while to think, this is a sub-question.

Without stopping, Lu Zhou quickly started to write, using explanatory language to answer various theoretical questions raised in the topic.

Seeing Lu Zhou's answer to this question, a smile of relief appeared on Academician Lu's face.

Yes, he did not look away.

This boy is a good seed to study theoretical physics. With the talents he now shows, he is even more hopeful to inherit his mantle than the four doctoral students he brings.

If it hadn't been for the school's talent training plan for him to go to a higher platform, he would even have thought that he would simply let him calculate on his own.

Of course, that's how he thinks about it. He goes to a higher platform to extract scientific research nutrients, and he also supports it.

After solving the second problem, Lu Zhou continued to look at the third problem.

But when he saw the third question, he froze.

The third question is a question about "string theory".

The so-called string theory is mainly trying to solve the apparently incompatible two main physical theories, namely the contradiction between quantum mechanics and general relativity, and to create a "theory of everything" that describes the entire universe, which is the legendary " Great Unification Theory. "

Speaking of which, the discovery of this theory has a lot to do with mathematics.

Vinecino, who worked at the European Nuclear Research Center, originally wanted to find a mathematical formula describing the strong force in the nucleus. As a result, he found the 200-year-old Euler formula in an old mathematics, and was surprised It was found that this formula can successfully describe the strong force of the solution he required.

It sounds a lot like the plot in martial arts, but it's just such a coincidence.

It was under this coincidence that the prototype of string theory was born.

Later, including the Bossian string theory, the superstring theory, and the m theory of "unification of rivers and lakes" proposed by the well-known Edward Witten, all developed on this basis.

It is almost the ultimate goal of theoretical physics to establish a "great unified formula" that describes everything in the universe.

However, it is more embarrassing that the development of domestic string theory is in a very awkward situation.

Condensed matter physics itself stands on the opposite side of theoretical physics. For the time being, the theoretical physics community seems unwilling to accept this "math freak."

Even including the best of domestic theoretical physics, Mr. Yang Lao, one of the most influential physicists in the world today, has expressed a point of disregard for string theory. UU Kanshu www.uukanshu.com is the domestic mathematics community, and it has an open and open attitude towards string theory. For example, Mr. Qiu Lao "crossed the line" and praised the string theory.

However, what makes Lu Zhou somewhat puzzled is that this third question examines not the knowledge of string theory, but asks his own opinions on string theory.

view?

What is your theory? Or is it a view of theoretical development?

Is this a subjective question?

The nib stopped on the paper for a long time, and the boat that passed the level to the final level was lost for a while.

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