Time passed by quickly.
On April 20th, Professor Lu Shenjian returned to Jin Ling University from Shanghai for a meeting. After the meeting, he asked Lu Zhou to go to his office.
When Lu Zhou walked in, the old man looked at him and smiled.
"How's the preparation going?"
Lu Zhou, "It's almost done … Professor, please go easy on me."
Professor Lu Shenjian, "Almost done? Okay then, I'll just test you with two questions. "
He opened his drawer and took out a piece of A4 paper. He then placed it on the table.
"The pen is here, do you want to write?"
Lu Zhou took the pen and paper and looked at the questions. His eyebrows twitched.
There were two questions, but there were three on the paper.
Furthermore, he had said that he would take the test as he wished, but none of the questions seemed easy …
Professor Lu Shenjian smiled and asked, "What, you don't understand?"
"Of course not," said Lu Zhou as he smiled and looked at the questions. He then said, "It looks a bit difficult."
Professor Lu Shenjian smiled and did not say anything. He crossed his legs and waited for Lu Zhou to start writing.
Not easy?
If it was easy, then what was the point of the exam?
He was an academician. How could a graduate student taught by an academician be the same as a graduate student taught by an ordinary professor?
These questions weren't meant for graduate students. Instead, they were meant to test the interviewees' professional knowledge when he was recruiting PhD students.
If one could solve two out of three questions, then they would pass. If one could solve three out of three questions, then they would be considered excellent.
The four doctoral students that he had mentored could all solve three questions. Although the questions were different, the level was about the same.
While Professor Lu Shenjian was waiting for Lu Zhou to start writing, Lu Zhou had already finished all three questions. He then looked at the first question, which was the easiest question for him.
The first question was about group theory.
However, it was not about group theory. It was about the application of group theory in quantum mechanics.
The "group theory" branch of mathematics was created by mathematicians before the emergence of "quantum mechanics", unlike "calculus", which was created by physicists and mathematicians. Therefore, group theory was an "imported product" for physicists. It was difficult to learn and difficult to use.
However, for Lu Zhou, who was "born in mathematics", it wasn't that difficult to deal with.
[Group Theory Explanation of Accidental Degeneracy of Hydrogen Energy Levels]
The question was short, but it contained a lot of information.
The phenomenon that the degeneracy of hydrogen is higher than that of ordinary atoms is called "accidental degeneracy". However, the phenomenon of accidental degeneracy could not be explained by traditional quantum mechanics. It was not until the introduction of group theory that this phenomenon was theoretically explained.
Lu Zhou closed his eyes and recalled the quantum mechanics knowledge he had learned before. He recalled everything about hydrogen atoms.
Then, he would build a mathematical model …
Opening his eyes, Lu Zhou took a deep breath, picked up the pen, and wrote on the paper.
[Let the hydrogen atom Hamiltonian be H. In the case of Coulomb potential, there is a Runge-Lenz vector in the system, recorded as M '= …]
[The eigenvalue of the group Casimir operator C = …]
[…]
When Professor Lu Zhou saw how fast Lu Zhou was answering the question, he raised his eyebrows.
He originally thought that Lu Zhou would take at least twenty minutes to think about this question. He didn't expect Lu Zhou to already start writing.
Also, the idea was completely correct.
Originally, he wanted to remind Lu Zhou when he couldn't think of an answer, but now it seemed like there was no need.
[For the energy level E (n + 1) and quantum number (n, 1), the degeneracy is Σ2 (l + 1) = n2 …]
When Professor Lu Zhou saw the answer, he nodded in his heart.
First question, correct!
Lu Zhou didn't notice the expression on Professor Lu's face. He continued to focus on the next question.
The second question was about the Dirac hole theory in quantum field theory. It examined the understanding of the Dirac equation and some theoretical knowledge about field theory.
This kind of pure theoretical knowledge wasn't difficult for Lu Zhou. Under the guidance of the drug, he basically wouldn't forget what he read.
For him, compared to the first question, which required him to think for a while, this was a free point question.
Without stopping, Lu Zhou quickly started writing and used argumentative language to answer the various theoretical questions raised in the question.
When Professor Lu Zhou saw that Lu Zhou answered this question, he had a smile on his face.
Not bad, he was right.
This kid was a good candidate for theoretical physics research. With his current talent, he had a higher chance of inheriting his legacy than his four PhD students.
If it wasn't for the fact that the school had developed a talent training plan for Lu Zhou, Professor Lu would have even thought about letting Lu Zhou do his PhD here.
Of course, he was just thinking about it. He supported Lu Zhou going to a higher platform for scientific research.
After solving the second question, Lu Zhou continued to look at the third question.
However, when he saw the third question, he was stunned.
The third question was about "string theory".
The so-called string theory was mainly an attempt to solve the contradiction between the two main physics theories that were incompatible on the surface, namely, quantum mechanics and general relativity. It wanted to create a "theory of everything" that described the entire universe, which was the legendary "Grand Unified Theory".
Speaking of which, the discovery of this theory had a lot to do with mathematics.
Venecino, who worked at CERN, originally wanted to find a mathematical formula that described the strong force in the nucleus of an atom. As a result, he found the 200-year-old Euler formula in an old mathematics book. He was surprised to find that this formula could successfully describe the strong force he was trying to solve.
This sounded like a plot from a martial arts novel, but it was a coincidence.
Because of this coincidence, the prototype of string theory was born.
Later, the Bosch string theory, superstring theory, and the famous M-theory proposed by Witten were all developed from this foundation.
Establishing a "Grand Unified Formula" to describe everything in the universe was the ultimate goal of theoretical physics.
However, the awkward thing was that the development of string theory in China was in a very awkward situation.
Condensed matter physics itself stood on the opposite side of theoretical physics, and the theoretical physics community didn't seem to be willing to accept this "mathematics freak".
Even Mr. Yang, one of the most influential physicists in the world and a leading figure in theoretical physics, expressed his disapproval of string theory. On the contrary, the Chinese mathematics community had an open attitude towards string theory. For example, Mr. Qiu had once "liked" string theory.
However, what Lu Zhou didn't understand was that the third question didn't test his knowledge of string theory. Instead, it asked him about his opinion of string theory.
Opinion?
Opinion on theory? Or opinion on theory development?
Is this a subjective question?
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