Chapter 156 The Academician's Test

time flies.

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

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

"How are you getting ready?"

Lu Zhou: "It's almost there... I hope the professor will show mercy."

Academician Lu: "Almost? That's fine, I'll just test you with two random questions."

As he spoke, he opened the drawer, pulled out a piece of A4 paper, and placed it on the table.

"Here is the pen, use it to write?"

Lu Zhou took the pen and paper, glanced at the title above, and twitched his brows severely.

There are two questions agreed upon, but three questions are clearly written on the paper.

Besides, it was agreed to take the exam casually, and none of the questions seemed easy...

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

"How come?" Lu Zhou smiled, looked at the question, with a thoughtful expression on his face, "It just looks a bit difficult."

Academician Lu smiled and said nothing. He crossed his legs and waited for him to write.

Not easy?

If it's easy, what's the point of passing the exam?

How can I say that he is also an academician, can the postgraduates brought by academicians be the same as the postgraduates taught by ordinary professors?

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

If you can solve two of the three questions, you are qualified. If you can solve three of the three questions, you can say that you are excellent.

The four doctoral students he brought himself were all at the level of being able to solve three questions. Although the examination topics are different, the levels are similar.

While Academician Lu was waiting for Lu Zhou to start writing, Lu Zhou quickly passed all three questions, and then looked at the first question, which was also the easiest question for him.

The first question examines group theory.

However, what is investigated is not the group theory in mathematics, but the application of group theory in quantum mechanics.

Since the mathematical branch of "group theory" was created independently by mathematicians long before the emergence of "quantum mechanics", it is not jointly founded by physicists and mathematicians like "calculus". Therefore, group theory is an "exotic product" for physicists, which is difficult to learn and difficult to use.

However, for Lu Zhou, who was born in mathematics and then entered mathematics and physics, it is not so difficult to deal with it.

[Group Theoretic Explanation of Accidental Degeneracy of Energy Levels of Hydrogen Atoms]

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

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

Closing his eyes, Lu Zhou recalled the quantum mechanics knowledge he had learned before, and recalled everything about hydrogen atoms in his mind.

Then, model it mathematically...

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

【Let the Hamiltonian of the hydrogen atom be H=P/2μ-Ze/r...】

[In the case of the Coulomb potential, there is a Runge-Lenz vector in the system, which is recorded as M’=……]

[The eigenvalue C=... of the group Casimir operator]

【…】

Seeing the speed at which Lu Zhou was doing the questions, Academician Lu raised his eyebrows slightly.

He originally thought that Lu Zhou would have to spend at least 20 minutes thinking about this question, but he didn't expect that he had already started writing.

Moreover, the train of thought is completely correct.

Originally, he planned to speak up when Lu Zhou couldn't figure it out, but now it seems that there is no need.

[For the energy level E(n+1) and the quantum number (n, 1), the degree of degeneracy is Σ2(l+1)=n...]

Seeing the answer, Academician Lu nodded silently in his heart.

First question, correct!

Lu Zhou didn't pay attention to the expression on Academician Lu's face, and continued to focus on the next question.

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

This kind of pure theoretical knowledge is not difficult for Lu Zhou. In the state of concentration guided by drugs, he will basically not forget what he has seen.

For him, compared to the first question, which requires a little thought, this is a bonus question.

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

Seeing that Lu Zhou had done this question, Academician Lu had a gratified smile on his face.

Yes, he really didn't miss it.

This kid is a good seed for studying theoretical physics. With the talent he has shown now, he is even more likely to inherit his mantle than the four doctoral students he brought.

If it wasn't for the fact that the school had already formulated a talent training plan for him to reach a higher platform, he even thought about letting him directly blog here.

Of course, that's what he was thinking about, and he also supported going to a higher platform to absorb scientific research nutrients.

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

However, when he saw the third question, he froze for a moment.

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

The so-called string theory mainly tries to solve the contradiction between the seemingly incompatible two major physical theories, that is, quantum mechanics and general relativity, and intends to create a "theory of everything" that describes the entire universe, which is the legendary "theory of everything". Grand Unified Theory".

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

Venecino, who works at CERN, originally wanted to find a mathematical formula to describe the strong force in the nucleus. As a result, he found the 200-year-old Euler's formula in an old mathematics book and wrote Surprisingly, it was found that this formula could successfully describe the strong force he wanted to solve.

This sounds like a plot in a martial arts novel, but the fact is such a coincidence.

Under such a coincidence, the prototype of string theory was born.

Including the later Bose string theory, superstring theory, and the M-theory of "unifying the rivers and lakes" proposed by the famous Edward Witten, are all developed on this basis.

Establishing a "grand unified formula" to describe everything in the universe is almost the ultimate goal of theoretical physics.

However, what is more embarrassing is that the development of string theory in China is in a very embarrassing situation.

Condensed matter physics itself stands on the opposite side of theoretical physics, and the theoretical physics community seems to be reluctant to accept this "mathematical freak".

Even the master of theoretical physics in China, Mr. Yang Lao, one of the most influential physicists in the world today, has expressed his disapproval of string theory. On the contrary, the domestic mathematics community is open to string theory. For example, Mr. Qiu has "liked" string theory across borders.

However, what puzzled Lu Zhou was that the third question was not about the knowledge of string theory, but about his own views on string theory.

view?

Thoughts on the theory? Or a view on theory development?

Is this a subjective question?

The pen tip stayed on the paper for a long time, and Lu Zhou, who passed all the way to the last level, was a little lost for a while.