"By the way, Pang, it's Christmas soon, I'm going to go back to the United States, and by the way, I'll finish the submission. Would you like to come with me to Princeton? ”

Edward Witten thought for a moment and said again.

Edward Witten signed a two-year contract with Tsinghua University, and he originally thought that it would take at least one to two years to develop M theory, but he didn't expect that before this year ended, he and Pang Xuelin had already completed the creation of M theory.

However, since he has come to Tsinghua University, Edward Witten has no intention of terminating the contract with Tsinghua University early.

In the past six months, Tsinghua University has given him a very high degree of freedom, and the cooperation with Pang Xuelin is also very comfortable.

The two exchanged views on the latest advances in physics and mathematics from time to time, and both felt that they benefited each other a lot.

And under the leadership of Edward Witten, Princeton and Tsinghua University have also reached a number of cooperation agreements.

It has even directly contributed to a joint postgraduate training program between the Department of Mathematics and the Department of Physics.

At the same time, Princeton University also put forward a suggestion, hoping that Pang Xuelin could become an adjunct professor at Princeton University, and only need to stay for three months every year.

In this regard, Pang Xuelin does not have much opinion.

After all, whether it is the patent issue of sildenafil and atorvastatin, or the future wants to make a difference in the Internet field, the United States is a country that cannot be bypassed.

Spending a few months in the U.S. each year helps Pang Xuelin gain a clearer understanding of the development of the Internet and the latest economic hotspots in the world.

Pang Xuelin said: "Okay, anyway, I have to go to Princeton for two months every year, so this time I will go to the United States with you at Christmas." ”

Witten smiled: "Well, when the time comes, come to my house for Christmas, I think Jenphne will definitely welcome you." ”

Jenphne is Witten's wife, with whom she has a son and a daughter, both of whom are adults.

The eldest son, who has just graduated from college, is a programmer and is said to have entered the Microsoft job.

The youngest daughter has just been admitted to the School of Cinematic Arts at the University of Southern California.

After Witten came to China, Jenvena came to stay for half a year, and Pang Xuelin got along well with Witten.

But this time I went to the United States, but Ah Qing couldn't go.

In the first half of this year, after Ah Qing transferred to the primary school affiliated to Tsinghua University, after the school test, because the foundation was too poor, he could only enter the fourth grade.

Fortunately, this girl is also competitive, coupled with Pang Xuelin's supervision and tutoring, in half a year, Ah Qing's grades have caught up from the bottom of the class to the top five.

If nothing else, there is no problem in entering Tsinghua High School after graduating from primary school.

"Ah Qing, this time my brother goes to the United States, you have to listen to Sister Liu's words, okay, at most three months, my brother will come back from the United States!"

Pang Xuelin touched Ah Qing's head and said.

"Hmm!"

Although Ah Qing's eyes flashed with reluctance, he still nodded obediently.

Pang Xuelin smiled, looked up and said to Liu Jiahuan: "Jiahuan, during this time, I will trouble you to take care of Aqing." ”

Liu Jiahuan looked at Pang Xuelin and said with a smile: "Professor Pang, don't worry, with me, you can go to the United States with peace of mind." ”

Since that interview at the beginning of the year, Pang Xuelin has maintained a good relationship with Liu Jiahuan.

Liu Jiahuan likes Ah Qing very much, and from time to time takes advantage of the weekend time to come to see Ah Qing and take her out to play.

Therefore, this time when he went to the United States, Pang Xuelin thought about it for a long time, but decided to open his mouth to Liu Jiahuan and hand over A-Qing to her to take care of.

Liu Jiahuan agreed in one bite.

Her family is in the suburbs of the capital, she works at CCTV, rents a small suite, and feels lonely when she lives alone on weekdays.

Now that she has A-Qing's company, she feels very happy.

On December 15, 1993, Pang Xuelin and Edward Witten officially boarded a flight to New York.

After a long flight of thirteen hours, the two arrived at Newark International Airport, and as soon as they stepped out of the passenger exit, they saw a young man who looked to be in his twenties, holding a sign with their names written on it, standing at the passenger exit.

"Hey, Add, long time no see!"

Edward Witten went up and hugged the other party, then turned around and introduced: "Pong, let me introduce you, this Morse Eddy, Deligne's assistant!" ”

"Hello, Professor Pang, it's a pleasure to meet you!"

Eddie warmly shook hands with Pang Xuelin.

"Add, I'm glad to meet you too!"

After a few words of greeting, Pang Xuelin and Witten followed Eddie to the parking lot and boarded a Chevrolet SUV.

Two hours later, the car drove into the small town of Princeton, where Princeton University had arranged for him to live opposite Witten's house—a small two-story cottage with two bedrooms upstairs, a living room, a study, a kitchen, a dining room, and a fireplace downstairs, and a rent of $1,000 a month, which Princeton University paid for Pang Xuelin.

After Pang Xuelin placed the luggage, Witten came and knocked on the door, saying that Jenphne had prepared dinner for their arrival.

That evening, Pang Xuelin dined at Witten's house, a typical American meal, mashed potatoes, pan-fried steak, tuna salad, and a roast turkey.

Early the next morning, Pang Xuelin and Witten went to Deligne's office together, and then went through the relevant procedures for an adjunct professor at Princeton University.

Although he only needs to teach one undergraduate course at Princeton every year and stay at Princeton for more than three months, Pang Xuelin can still receive a salary of $5,000 a month, which is 20 times his salary in China.

It is said that bigwigs like Deligne and Wiles have an annual salary of more than $300,000.

After completing the entry procedures, because there was still a week to go before the Christmas holiday, Pang Xuelin had nothing to do for a while.

So on the third day of coming to the United States, Pang Xuelin went to the second-hand car market and spent $12,000 to buy a five-year-old second-hand Ford Tempo as a means of transportation during his stay in the United States.

He got his domestic driver's license as early as August this year, and before coming to the United States, he applied for an international driver's license translation, plus he was used to the traffic rules in the United States in his previous life, so he didn't worry about driving.

On December 19, early in the morning, Pang Xuelin got up and drove out.

This time, his destination was Cambridge, located in the Boston area of Massachusetts, northeast of New York.

It took nearly five hours for Pang Xuelin to finally arrive at Harvard University.

Parking the car in a parking lot on the campus of Harvard University, Pang Xuelin got out of the car and strolled around the campus.

He did not tell Wang Muhui in advance the news of his coming to the United States, and this time he came over as a surprise for her.