Great Country Academician

Looking at the clock hanging on the blackboard, there are still a few minutes before the end of the open class.

Xu Chuan thought for a while and said, "There is still a little time before the end of get out of class. If there are students who don't understand what was just said in class, they can ask questions now."

It was said that many students in the audience were eager to try, but they hesitated when they saw that the people around them didn't respond.

Of course, there must be people who know how to seize opportunities. A big man with a Nobel Prize + Philippine Award will answer his doubts in person. Such an opportunity may be rarely encountered once in a lifetime.

Xu Chuan stretched out his hand to signal a student to ask a question, and the selected student stood up reflexively.

"Professor." The student who was called didn't seem to expect that he would be so lucky. After he stood up, hundreds of people in the audience were watching him, and he stuttered immediately.

Xu Chuan smiled and didn't make a sound, but quietly waited for the other party to come over.

After taking a few deep breaths, the lucky guy was relieved, and then said: "Well, that, I remember that you just mentioned in class that you can understand the eigenvectors and eigenvalues ​​of square matrices from the perspective of algebraic geometry, I would like to ask Take a look at this."

"That's an interesting question."

Xu Chuan smiled and said, picked up the chalk from the table again, turned around and wrote on the blackboard behind him: "The eigenvectors and eigenvalues ​​of a square matrix are defined as follows from an algebraic point of view:

"Assuming n-order matrix A, if there is a number λ and n-dimensional non-zero column vector x→, so that the following formula is established: Ax→=λx→, then λ is called the eigenvalue of the matrix, and the non-zero column vector x→ is called a matrix, The eigenvector corresponding to the eigenvalue λ."

"To understand the eigenvectors and eigenvalues ​​of a square matrix from a geometric point of view, the matrix is ​​regarded as a coordinate system transformation, such as Ax→=λx→, which means that after the coordinate system transformation, the eigenvector becomes the original λ times, and the extension of the direction does not change, the direction is the same or opposite"

"At this time, the eigenvectors can be understood as those vectors that are unchanged in the direction of the extension line under the transformation of the coordinate system, but will be extended by λ times, the magnification of this length."

"In addition, it is worth noting that the eigenvector and the eigenvalue have a corresponding relationship. An eigenvector corresponds to an eigenvalue.

When solving the eigenvectors and eigenvalues ​​of a matrix, the eigenvalues ​​are generally obtained first, and then the eigenvalues ​​are substituted into the equation Ax→=λx→ to obtain the eigenvectors. "

In front of the blackboard, Xu Chuan wrote the last stroke, turned his head to look at the student who was still standing, and asked with a smile, "Do you understand?"

The student who asked the question nodded abruptly, and said excitedly, "Understood! Thank you, professor."

Xu Chuan smiled, and then selected students to answer their doubts.

With the leadership of the first student, the students who were hesitant before mustered up the courage to raise their hands, but at this moment, considering the hundreds of hands raised in the entire lecture hall, the probability of being selected is too small.

After answering a few questions, Xu Chuan smiled and said, "The last question is up to you. That student who wears glasses, what doubts do you have?"

"Professor, can you tell me how you solved Hodge's conjecture?"

The student wearing glasses stood up excitedly and asked, but he didn't mention the doubts in class, but asked a question about other aspects.

Hearing this question, Xu Chuan was slightly stunned. He didn't expect that this student would ask such a question, but it was not something that couldn't be answered.

With a smile, he said with some nostalgia: "The solution to Hodge's conjecture is the inspiration I got from Professor Mirzakhani. At the beginning, Professor Mirzakhani left me a manuscript. By studying that manuscript, I Unexpectedly, some solutions to Hodge's conjecture were obtained."

"As for the specific process"

After a pause, Xu Chuan continued to laugh and said, "This can't be explained in just one or two sentences, and it's too early to say these things for you guys now."

"Based on your current foundation, most of you may not even be able to fully understand the true meaning of the Hodge conjecture. As for my proof paper, let alone think about it, even if I explain it here today. I am afraid that more than 99% of the people present will not understand the report."

"For this kind of top-level conjecture in the current mathematics world, I suggest that you take it step by step, lay the most basic things first, try to break through your own boundaries, and then move towards your goals and ideals step by step. struggle."

"As for now, it's still too early for you."

Xu Chuan didn't talk much about how he solved Hodge's conjecture. As he said, he didn't despise or look down on him, but it was really too early for the students sitting in this classroom to say these things.

Not everyone is a genius like Tao Terence or Schultz, who can have extremely high attainments in mathematics at the undergraduate or graduate level.

As soon as he finished speaking, someone asked: "Professor, can you tell me what you are studying after returning to China? Physics, mathematics, or astronomy? I think many people are very interested in your research direction, including We're also curious."

Xu Chuan thought for a while and said with a smile: "NS equations and particle physics, I'm mainly studying these things during this time."

He didn't reveal his real research in this class, but just found a reason to perfunctory. Some things can be announced after completion, but they still need to be kept secret during the process.

"Ring ring ring ring."

When the bell rang for the end of get out of class, Xu Chuan put away the textbooks he brought, and slipped away without even turning off the projection equipment.

There are so many students here, if they get blocked, they won't be able to leave for a while.

After all, it was the first time the class started, and these students were quite enthusiastic, so before they could react, it was the best plan to do thirty-six tricks.

When there are more classes in the future, the students will get used to it, and they will no longer have to worry about being stuck in the crowd.

There is still a big difference between college students and those fanatical star-chasing fans. The former will still feel embarrassed, but as for the latter, I won’t say much.

What happened to sneaking into one's idol's house to steal underwear, personal items, and rushing on stage.

After a stroll, Xu Chuan came all the way to Chen Zhengping's office.

He knocked on the door, and there was a voice from inside. He pushed open the door and walked in. To his surprise, his tutor Chen Zhengping was not the only one in the office, and Liu Gaojun, the principal of Nantah University, was also here.

"Teacher, principal." Xu Chuan greeted with a smile.

"Professor Xu is here, sit down quickly." President Liu greeted with a smile: "It's the first time to teach at Nantah University, how do you feel?"

Xu Chuan said with a smile: "Very good, the students are very serious and enthusiastic."

"Hahahahaha, you are the only one with this charm." Liu Gaojun laughed and said, "If there is anything you are not satisfied with, or if you have any suggestions for teaching in class, you can ask me, and the school will Try to find a solution."

Xu Chuan nodded and said with a smile, "Of course."

On the side, Chen Zhengping interjected and asked, "The data analysis you sent to my mailbox two days ago is the experimental data of the ALICE detector?"

"Well, during the years before and during the Chinese New Year, I analyzed the experimental data of the ALICE detector. Thanks to your help, my mentor, I found some abnormal signals and data from it."

"It has been sent to Weiteng and CERN. I hope they can do a few sets of collision experiments to see if they can verify the analysis results."

Chen Zhengping pondered for a while, and then said: "Do you think that is the performance of inert neutrinos?"

As soon as Xu Chuan sent the analysis data and Daritz diagram to his mailbox, he had read it.

Although he was amazed at the speed with which his student was doing research, he still carefully studied and analyzed these Daritz diagrams.

Judging from the image, there may indeed be a new particle in the data analyzed by Xu Chuan, and the probability is not small.

But it is only possible, and even if there is a particle, it is not necessarily a sterile neutrino.

Although the focus of his research has now been on material physics, he was born in high-energy physics and condensed matter physics.

Moreover, the research on high-energy physics and particle physics has never stopped. Every year, I go to CERN to participate in research and data analysis, and I also keep an eye on the cutting-edge information in these two fields.

The sterile neutrino, which is not a particle in the Standard Model.

In the current theory of physics, inert neutrinos are a kind of dark matter, but no trace of dark matter has been found in the physics world. All theories are based on the movement of celestial bodies, the phenomenon of Newton’s universal gravitation, gravitational lens effect, The formation of the large-scale structure of the universe and the observation results of the microwave background radiation have been established.

For Chen Zhengping, although he believes in the existence of dark matter, he does not believe that it can be observed with today's technology.

Unless all aspects of the Large Intense Particle Collider are upgraded on a large scale, it is almost impossible to detect the existence of dark matter based on the current level of collision energy and the observation level of detectors.

Therefore, even if there is a new particle or some undiscovered phenomenon in the experimental data of the ALICE detector this time, Chen Zhengping does not think it is an inert neutrino.

In the office, Xu Chuan nodded and said, "Yes, I think it is very likely that it is an inert neutrino."

Chen Zhengping asked: "Have you considered the probability that this is an antineutrino?"

Judging from Xu Chuan's analysis results, he feels that this may be an unknown neutrino or antineutrino particle.

The so-called antineutrino particles are not antimatter, but another state of neutrinos.

Neutrinos spin in the opposite direction of motion, while antineutrinos spin in the same direction as their motion.

The nature of their interaction with matter is different, neutrinos only have left-handedness, and antineutrinos only have right-handedness.

It is the hypothesis of the existence of neutrinos put forward by Pauli, an Austrian physicist. In 1965, two physicists, Curwin and Rhines, used the beta decay of nuclear reactor products to produce antineutrinos and observe them.

So in theory, it is also possible to produce it in a large-scale strong particle collider.

Xu Chuan said: "I have considered it, but theoretically speaking, the probability of it being an unknown neutrino or antineutrino is much lower than the probability of being an inert neutrino."

Hearing this, Chen Zhengping asked quickly with interest: "How do you say?"

He still has some understanding of this student. If there is not enough evidence, this student will not say such things easily.

Since he said that the probability of being an inert neutrino is higher, he must have some evidence in his hands.

If it is really possible to confirm that traces of inert neutrinos have been found in the experimental data of the ALICE detector, it will be a super single-quantity nuclear bomb for the entire physics world, even the entire scientific world, and even the entire society!

After all, the inert neutrino is one of the warm dark matter particles that constitute the dark matter according to the current theory.

If it is confirmed, then the discovery of dark matter will become the most sensational news in the world of physics and even science this year.

Xu Chuan pondered for a while, and after sorting out his thoughts, he said, "From the Daritz diagram I made, we can clearly see the energy level trajectory of this new particle, which presents a ︺-shaped arc. , which is quite different from all regular particles."

"Even the kinetic energy trajectories of neutrinos and antineutrinos on the Daritz diagram do not appear this way, so it is likely to be a new type of particle, and its performance characteristics are not included in the conventional Standard Model in the particle."

"Secondly, I don't know if you have noticed, mentor, that on all the Daritz diagrams, the data representing this unknown new type of particle is all intermittent."

"This means that the experimental data observed by the ALICE detector is actually not perfect. What it can detect and record is only a part of the resonance state structure that this unknown particle can exhibit."

"Inert neutrinos are theoretically part of the warm dark matter in dark matter. In theory, warm dark matter does not participate in the strong interaction, otherwise the process of primary nucleosynthesis will be disturbed, and the abundance of light elements will occur. changes that would result in inconsistencies with current observations."

"In large strong particle colliders, the existence of primordial nuclei can be ubiquitous. In this case, only when inert neutrinos synthesize warm dark matter, the remaining abundance obtained from the thermal decoupling mechanism can be detected. Observed by ALICE probe. From this point of view, there is no doubt that it meets the requirements."

"In addition, Weakly Interacting Massive Particle (WIMP) is one of the most widely discussed candidates for dark matter, it refers to a certain kind of stable particle whose mass and interaction strength are near the electroweak scale, obtained through thermal decoupling mechanism Known remaining abundance"

"In the standard model of particle physics known to mankind, there is no particle that satisfies these properties at the same time, which means that this property must be a new physical particle beyond the standard model"

"From the above points of view, the probability that this new type of particle is an inert neutrino is quite high."