It seems that the class has not been long since it started.

Gently pushed open the back door and glanced at the middle-aged professor with his back to the classroom board, Lu Zhou did not disturb him and other classmates who were listening to the class, and did not even disturb the buddy who was sleeping on his stomach next to the door, but just found an inconspicuous position in the back row of the lecture hall and sat down very low-key.

Inspiration doesn't come by itself, you have to find it yourself.

Lu Zhou agrees with what Fermi once said, thinking about why some obvious questions are obvious can help deepen the understanding of those profound and difficult questions.

There is a precedent for this sentence, whether it is placed in physics or mathematics.

In the past, when he was at Princeton, if he encountered a difficult problem that he couldn't solve, Lu Zhou would find time to give a few lectures to undergraduates, or occasionally go to other professors' classes to find inspiration.

For example, when he was studying Goldbach's conjecture, Professor Feverman gave him a lot of inspiration in a class on number theory. And this is not because of how profound things he talked about in class, on the contrary, what he said at the time was only very easy to understand......

After finishing the board book on the blackboard, the middle-aged professor standing on the podium cleared his throat and spoke.

"Quantum mechanics is a very esoteric subject, and if you really understand it in depth, its existence will even subvert your understanding of the microscopic world, of physics, and even of classical philosophy. While I know my voice might be good for sleeping, I don't recommend you to start sleeping from the first class......"

The classroom resounded with good-natured laughter, and Lu Zhou, who was sitting in the back row, couldn't help but laugh.

It seems that this professor is also a young scholar with a bit of teaching level, at least he didn't read the preface according to the PPT as soon as he opened the textbook.

It's just that his voice is not loud and may be a hard injury.

At least the buddy sitting next to Lu Zhou has no plans to wake up yet.

Glancing at the few who had woken up, and the few who hadn't, the middle-aged professor shrugged humorously and continued his sermon without paying attention.

"We all know that some time ago, the STAR-2 demonstration reactor in Haizhou was successfully ignited under the command of Professor Lu of our school, and our country's controllable fusion power generation technology has also been at the forefront of the world, becoming the only country to build a commercial reactor."

Hearing this, Lu Zhou, who was sitting in the back row listening to the class, was suddenly embarrassed.

How can you talk about quantum mechanics that can be related to him?

Again, this is not plasma physics.

However, the professor on the stage spoke quite energetically, and the students in the lecture hall were obviously full of interest in this topic, and even the buddy who was sleeping soundly next to Lu Zhou raised his head sleepily and looked at the podium with a confused expression.

At this time, Lu Zhou noticed the name of the teacher and the phone number written on the title page of the quantum mechanics textbook under his arm.

Zhang Zhongqing?

Haven't heard of it......

“…… According to public data, the STAR-2 demonstration reactor - or the current Pangu reactor - has a peak temperature of 130 million degrees Celsius inside the core, which is nearly 9 times the temperature of the center of the sun! ”

Looking at the students who were exclamating in the classroom, Professor Zhang, who was standing on the stage, was secretly happy in his heart, knowing that he had successfully captured the attention of the students, he immediately hit the railway while it was hot.

"At such a temperature, ordinary materials must not be able to withstand it. Therefore, our country's STAR-2 demonstration reactor adopts the method of magnetic confinement, which confines the deuterium-tritium mixture of ionization I participating in the reaction in a closed magnetic cage. ”

"So the question is, I want to ask the students, why does controlled fusion require such a high temperature to react? Or to put it another way, why can't fusion reactions be carried out at room temperature? ”

The classroom fell silent.

The buddy sitting next to Lu Zhou pursed his lips and muttered something in a low voice.

"Isn't this nonsense?"

happened to hear this complaint, Lu Zhou raised his eyebrows with interest, and was about to ask him what he thinks. But before Lu Zhou could speak, he continued.

“…… If this can be done at room temperature, not everything can be nuclear fusion. ”

Lu Zhou: "......"

"Can any of you stand up and speak?"

Glancing at the classroom where no one raised their hands, Professor Zhang, who was standing on the podium, had to add, "This question has the usual grades." ”

Whew!

Hearing that there were usual grades, more than half of the people in the classroom instantly raised their hands.

"I know!" After receiving the professor's signal, the bespectacled female student who was sitting in the first row stood up and replied quickly, "Since the nucleus is positively charged, there is a Coulomb repulsion between the nucleus. Only when the two nuclei are close enough can the strong interaction force overcome the Coulomb repulsion force and bring the two nuclei together. On the macro level, only by increasing the heat in the system and accelerating the thermal movement of the molecules in the system can the nuclei collide together with sufficient kinetic energy and a fusion reaction occurs. ”

"That's a good answer," the middle-aged professor cleared his throat and continued with a smile, "Then the question is, have you ever thought about why strong interaction forces can only occur at very short distances?" ”

"Because...... Is it a short-range force? ”

"This is the explanation of a high school physics textbook, and it is no different from saying it and not saying it," Professor Zhang smiled, motioned for the student to sit down, and continued, "You are now college students, and you should know not only the 'what', but also the 'why'." ”

"Quantum field theory tells us that interparticle interactions do not interact at a distance, but unfold through some kind of boson as a medium. For example, electromagnetism exchanges photons, strong interactions exchange gluons or mesons, and weak interactions exchange Z bosons...... Some people may ask, what does this have to do with the range of force we are talking about? ”

As he spoke, Professor Zhang turned to face the blackboard and preached as he wrote.

"Suppose the scattering (p+k→p'+k') between two resolving fermions, then under the Berne approximation, we can find that the scattering cross-section and the interaction can have the following relationship......"

【<p'|iT|p>=-iV（q）（2π）δ（Ep'-Ep），（q=p'-p）】

【……】

Who am I?

Where am I?

Looking up at the equation on the blackboard, the buddy sitting next to Lu Zhou had a confused expression, wondering if he had slept in class.

"Hold the grass? Aren't you talking about nuclear fusion...... What time is it today? ”

Even though he was just distracted for two seconds, he felt like he had missed a semester's worth of classes.

In fact, it's not just him.

The people sitting in the classroom could understand less than half of what Professor Zhang was talking about.

Glancing at the bewildered buddy next to him, Lu Zhou smiled and asked softly.

"Want to know?"

"Think...... Can you read it? The buddy glanced at Lu Zhou with a confused expression, probably because he didn't wake up, so he didn't realize who was sitting next to him.

Lu Zhou smiled and said, "If you want to, then I'll teach you." ”

Stopping the chalk in his hand, Professor Zhang turned around and looked at the confused students, the corners of his mouth curled.

It's normal not to understand.

Quantum mechanics itself is a difficult part of physics.

Especially when it comes to calculations, it is not possible to do without a certain mathematical foundation.

Speaking of himself, there is nothing wrong with making a conclusion, but if he is asked to calculate on the spot, he may not be able to calculate it before the end of class.

"The calculation process is very complicated," Professor Zhang said with a smile as he threw the chalk in his hand on the lectern table, putting his hands behind his back and smiling, "If anyone can complete the rest of the course, I will give him all the usual grades in this course, and I won't have to take this class in the future." ”

The lecture hall was as quiet as death.

The students looked at each other.

Even those graduate students who came to skip classes were also confused.

Professor Zhang smiled and shook his head, and just as he was about to lay out the question as a reflection question, a voice came from the back row of the classroom.

"Can I use the blackboard?"

Zhang Zhongqing: "......??? ”