Chapter 605: Why Do Nucleons Stick Together?
Translator: Henyee Translations Editor: Henyee Translations
The cla.s.s seemed to have just begun.
Lu Zhou gently pushed open the back door and looked at the middle-aged professor facing the cla.s.s. Lu Zhou didn’t interrupt the students who were listening to the lecture, nor did he interrupt the students with their heads on their desks. He found a low-key spot and sat down.
Inspiration didn’t just come by itself, he had to go search for it.
A quote by Fermi resonated with Lu Zhou, which was that thinking about easy problems would depend on one’s understanding of esoteric problems.
This seemed to apply to both mathematics and physics.
When Lu Zhou was in Princeton, whenever he encountered a problem he couldn’t understand, he would take time to lecture some undergraduate students, or he would go to other professors’ cla.s.srooms to find inspiration.
Like when he was studying the Goldbach’s conjecture, Professor Fefferman’s number theory lecture gave him a lot of inspiration. This wasn’t because Fefferman’s lecture content was deep and complex; it was the opposite. Fefferman’s lectures were all easy material…
When the professor on stage finished writing on the blackboard and cleared his throat, he began to speak.
“Quantum mechanics is a very difficult field. If you really go deep into the field, its content will subvert your understanding of the micro-universe, physics itself, and even philosophy. Even though I sound boring, I don’t recommend you guys to sleep in the first lecture…”
There was laughter in the cla.s.sroom, and Lu Zhou, who was sitting in the back row, couldn’t help but smile.
It seemed like this professor was a young scholar. At the very least, he didn’t read verbatim off a PowerPoint presentation.
However, his voice wasn’t quite loud enough.
Because the guy sleeping next to Lu Zhou didn’t wake up.
The professor glanced at the students and shrugged. He then continued to speak, “We all know the STAR-2 demonstration reactor in Haizhou was successfully ignited under the command of Professor Lu from our school. Our country’s controllable fusion reactor technology is at the forefront of the world, and we are the only country that has a commercial reactor.”
Lu Zhou, who was sitting in the back row, was a little embarra.s.sed.
Why is a quantum mechanics professor talking about me?
It’s not like this is a plasma physics cla.s.s.
However, the professor on stage was quite enthusiastic, and the students in the lecture hall were also interested. The guy that was sleeping next to Lu Zhou woke up and looked at the professor with a muddled look on his face.
Suddenly, Lu Zhou noticed that the teacher’s name and phone number were written on the t.i.tle page of the quantum mechanics textbook, which was under the student’s arm.
Zhang Zhiongqing?
I haven’t heard of him before…
“According to the public data, the STAR-2 demonstration reactor, or the Pangu reactor, has an internal nuclear core temperature of 130 degrees, nearly nine times the temperature of the sun’s core!”
The students in the cla.s.sroom were amazed, and Professor Zhang, who was standing on the lecture stage, knew that he had successfully captured the students’ attention. So, he immediately followed up with more information.
“Normal temperatures can’t stand a temperature like this. So, our country’s STAR-2 demonstration reactor uses magnetic confinement to constrain the deuterium-tritium mixture, confining it in a magnetic cage.
“Then the question comes, my students, what temperature is required for fusion reaction? In other words, why is fusion reaction not carried out at room temperature?”
The cla.s.sroom went quiet.
The guy sitting next to Lu Zhou snorted.
“No sh*t…”
Lu Zhou raised his eyebrows with interest. He was about to ask him for his opinion but the student spoke first, “If it’s carried out at room temperature, then it can’t be nuclear fusion.”
Lu Zhou: “…”
“Is there a student that can stand up and tell us the answer?”
Professor Zhang’s eyes swept across the room. When no one raised their hand, he said, “You’ll receive bonus marks if you answer this question.”
There was a commotion in the cla.s.sroom.
Half of the students in the cla.s.sroom raised their hands.
The professor nodded at a gla.s.ses-wearing female genius student who was sitting in the front row. She quickly said, “I know! It’s because the nucleus is positively charged, so there is a Coulomb repulsion force between the nuclei. Only when the two nuclei are close enough can the strong interaction force overcome the Coulomb repulsion and polymerize the two nuclei. Looking at it from a macroscopic scale, one would have to increase the heat in the system and accelerate the thermal motion of the molecules in the system to create enough kinetic energy to cause a fusion reaction.”
“Good answer.” The professor wrote down her name and cleared his throat. He then smiled and asked, “Then the next question is, why does the strong interaction only happen at short distances?”
“Because of… the short-range force?”
“That’s a high school textbook explanation, it’s not quite what I’m looking for.” Professor Zhang smiled and gestured the student to sit down. He then said, “You guys are already university students, so you should know the ‘why’, in addition to the ‘what’.
“Quantum field theory tells us that the interaction between particles is not an action at a distance effect, but is actually carried out by using a boson as a medium. For example, electromagnetic waves are photons, and strong interaction is a gluon or a meson, weak interactions are the W and Z bosons… Some people might ask, what does this have to do with the range of the force we are talking about?”
Professor Zhang turned toward the blackboard and began to write.
“When scattering occurs between two resolvable fermions (p+k→p’+k’), under the Berne approximation, we can conclude that the scattering cross-section and the interaction have a relations.h.i.+p…”
[
= -iV(q)(2π)δ(Ep’-Ep) , (q = p’-p)]
[…]
Who am I?
Where am I?
The student sitting next to Lu Zhou was muddled. He looked at the blackboard and thought he was dreaming.
“F*ck me, isn’t this supposed to be nuclear fusion… What day is it?”
It had only been two seconds, and he felt like he had missed an entire lecture.
He wasn’t the only one who felt this way.
Less than half of the cla.s.s was able to understand what Professor Zhang wrote on the blackboard.
Lu Zhou looked at the muddled guy next to him and smiled as he asked quietly, “Do you want to know?”
“I do… You understand?” The muddled guy looked at Lu Zhou. Maybe because he just woke up, he didn’t recognize Lu Zhou.
Lu Zhou smiled and said, “If you want, then I’ll teach you.”
Professor Zhang stopped writing and turned around. He then looked at the muddled students and smiled.
It’s normal to be confused.
Quantum mechanics is the hard part of physics.
Especially when it comes to the calculations, one would have to have a certain mathematics background.
He could write down a conclusion with no problem, but if someone made him calculate a quantum mechanics problem on the spot, he might not be able to do it in one lecture’s time.
“The calculation process for this part is very complex.” Professor Zhang threw the chalk on the desk and smiled with his hands behind his back. He said, “Whoever can finish the rest of the equation, I’ll give them full marks for the non-exam grades, and they won’t have to come for my cla.s.ses in the future.”
The cla.s.sroom was dead silent.
The students looked at each other.
Even the graduate students that came here for fun, were muddled.
Professor Zhang smiled and shook his head. He was about to give this problem as a challenging homework task, but then, he heard someone speak from the back of the cla.s.sroom.
“Can I use the blackboard?”
Zhang Zhiongqing: “… ???”