and Witten reached a consensus on cooperation, and Pang Xuelin stayed in Princeton for a few more days.

In the past few days, it was mainly Witten who explained some of his ideas on M theory to Pang Xuelin, and Pang Xuelin established a mathematical structure model of this theory through the method of Ponzi geometry.

Although Pang Xuelin has seen the relevant concepts and ideas of M theory in the real world, he is not a theoretical physicist after all, and his accumulation in physics is far less profound than that of Witten.

Moreover, there must be some differences between the M theory, which has been re-established through Ponzi geometry, and the M theory in the real world.

Therefore, in the past few days, Pang Xuelin has also taken out the relevant concepts of M theory in the real world and discussed it with Edward Witten.

In this way, Witten was pleasantly surprised.

Because many of the ideas put forward by Pang Xuelin coincided with what he had thought of, some of which even Witten himself had never thought of.

After a few days of discussion, the two sorted out their respective division of labor.

Witten was mainly responsible for the theoretical work, he proposed a new idea, and then Pang Xuelin established the corresponding mathematical structure through Ponzi geometry, and then used the mathematical calculation results to reverse whether the theory was valid.

Since Pang Xuelin also had to participate in media activities and go to various universities to give presentations, the two had to agree to communicate by email once a week.

Fortunately, NSFnet, the backbone of the Internet between universities, has been established in the United States, and the use of e-mail has become common in academia.

Therefore, Pang Xuelin does not have to worry about how to contact Witten in a short time.

The question is, how should Pang Xuelin contact him after returning to China?

It was not until April 20, 1994 that China's Internet was fully connected to the Internet through the 64K private line of Sprint in the United States.

Although China completed the first national e-mail as early as 1986, only a small number of domestic computers can be connected to foreign countries, most of which are limited to a few units such as the Institute of Computer Science of the Chinese Academy of Sciences, and whether it can complete the e-mail sending and receiving with Princeton University is also a problem.

"Pang, if you don't stay at Princeton for half a year, within half a year, we will definitely be able to produce results!"

In the café, Edward Witten, who was sitting opposite Pang Xuelin, suggested.

Pang Xuelin shook his head and said with a wry smile: "This is not good, there are still a lot of things in my country?" In addition, I came to the United States with my sister this time, and I couldn't stay in the United States by myself and let her go back alone. ”

Although it is interesting to co-create M Theory with Witten, Pang Xuelin has not forgotten his mission to enter this world.

My most important job is to improve the level of education in the poor areas of the country.

Therefore, it is simply impossible for him to stay abroad for a long time.

Witten frowned, suddenly raised his head and said, "Otherwise, since you can't stay in the United States for a long time, then why don't I go to China, and I will find a teaching position in Shuimu or Peking University, so that we can guarantee the progress of the research?" ”

"Are you sure you want to go to China?"

Pang Xuelin was slightly stunned and said with some surprise.

Witten smiled: "Where to go is not research, I have a hunch that with your joining, our new theory will definitely shock the world!" ”

Pang Xuelin laughed and said, "Okay, then let's say okay, when I finish my trip in the United States, let's go back to China together!" ”

"Then it's decided!"

Witten raised the coffee cup and touched Pang Xuelin lightly, and the two looked at each other and smiled.

……

After having dinner with Witten, Pang Xuelin returned to the hotel room and directly found Xie Yongxin, president of the Chinese Mathematical Society, and told him Witten's idea of going to China.

"What, Edward Witten is going to China?"

Xie Yongxin stood up from the sofa all of a sudden, and said a little incredulously.

Pang Xuelin said with a smile: "Yes, there is a topic, he needs to cooperate with me in research, and I can't stay abroad for a long time, so I have to let him come to China, which he took the initiative to propose." I am not familiar with the key domestic scientific research units, and I don't know which unit to contact. ”

Xie Yongxin looked at Pang Xuelin a little sluggishly, and it took a long time to come to his senses.

In later generations, it is not uncommon for Fields Medal winners or Nobel laureates to work in China, but in this era, a Philippine Medal bigwig, and also a top theoretical physicist, is almost the only one to work in China.

Xie Yongxin was curious: "Mr. Pang, what kind of topic are Professor Witten and you cooperating on?" ”

Pang Xuelin said: "It is mainly in superstring theory. ”

Xie Yongxin nodded and said, "If Professor Witten wants to go to China, I believe that no matter which unit should welcome it, the key is Mr. Pang, where are you going to work next?" If you have decided on a unit, then I think Professor Witten will definitely go to the same unit as you. ”

"I ...... myself"

Pang Xuelin lowered his head and pondered.

Pang Xuelin knows very well that after he returns to China, it is basically unlikely that he will return to Lingziding Village to continue to serve as his primary school teacher.

Even if he had the will, the state would not have allowed it.

A mathematician at the level of a Philippine award bigwig, and then serving as a rural teacher, can be laughed to death in the world.

Then finding a suitable school or scientific research unit to attach to it has become a problem that Pang Xuelin needs to consider urgently.

Pang Xuelin pondered for a moment, raised his head and said, "President Xie, I'm going to go to Tsinghua University." ”

"Go to Tsinghua University, why? Peking University is the best majoring in mathematics and physics. ”

Xie Yongxin was slightly stunned.

Traditionally, whether it is mathematics or physics, Peking University is better than Tsinghua University in this era.

Originally, Peking University and Tsinghua University were both comprehensive universities, but in 1958, the colleges and universities were adjusted, and the science departments of the capital universities, mainly Tsinghua University, Peking University, and Yenching University, were adjusted to Peking University; The Department of Engineering was adjusted to Tsinghua University.

Therefore, in the 40 years from 1960 to 2000, Peking University was the university with the highest comprehensive level of liberal arts and sciences in China, while Tsinghua University was the university with the highest comprehensive level of engineering.

Pang Xuelin said with a smile: "It's because Peking University's mathematics and physics majors are strong enough, we didn't have a good time in the past, so it's better to go to Tsinghua University to be comfortable." ”

Having said that, Pang Xuelin knows very well that the reason why he chose Tsinghua University is only because of Tsinghua's engineering background, which is more suitable for him to play his skills in the future.

In this regard, Xie Yongxin can only sigh that he is talented and humane.

With Pang Xuelin's current academic status, in the domestic academic community, although it is not crushed, ordinary people really have nothing to do with him.

Xie Yongxin said with a smile: "That's okay, I happen to be familiar with Luan Jingtong from Tsinghua University, do you want me to say hello to you in advance." ”

"Okay, President Xie, then I'll trouble you."