I don't know how long it took, Pang Xuelin opened his eyes a little dazed, and the first thing that caught his eye was a snow-white ceiling.

The windows were filled with moonlight, and compared with the softer artificial light source in the dungeon, the natural light in front of him was dark and dark, which made Pang Xuelin a little unaccustomed, but he had a sense of intimacy for no reason.

Pang Xuelin turned over and picked up the time on the bedside table, which was shown as November 6, 2019, 19:30 p.m.

Pang Xuelin remembers that he entered the Wandering Earth World at 00:00 on November 5, 2019, and he spent 22 years in the Wandering Earth World, but only 19 hours passed in the real world.

In a flash in the pan, the vicissitudes of life.

Pang Xuelin has never felt so much that time is such a terrifying existence.

Thinking of Yao Bingxia, Pang Xuelin's heart was still throbbing for a while.

Although he knew that once he returned to the real world, sooner or later he would still be separated from Yao Bingxia, but at this moment, he was still a little difficult to accept.

"In the future, in the dimensional world, you must never fall in love again!"

After being stunned for a while, Pang Xuelin felt his stomach gurgle for a while.

Although the system once said that after entering the plane world adventure, you can reduce the body's metabolism and ensure the supply of nutrients.

But the food in the stomach will still be digested, and you will still be hungry.

Pang Xuelin picked up his mobile phone, changed his clothes, and then went out to find something to eat.

Tonight is a rare full moon night, the bright moon hangs high in the air, the night wind blows the fallen leaves rustling all over the ground, it is late autumn, and there is a chill in the air, but Pang Xuelin feels an unprecedented sense of intimacy.

Recalling the world of the Wandering Earth that has long been unrecognizable, this calm and serene world in front of me is the real golden age!

Pang Xuelin stood at the entrance of the building, closed his eyes and enjoyed the beauty of the real world for a while, when he was suddenly patted on the shoulder, and a crisp voice suddenly interrupted his thinking.

"Junior brother, what are you doing standing here?"

Pang Xuelin opened his eyes, and what greeted him was a beautiful girl, with a delicate face and a well-proportioned figure, and the tone seemed to be very familiar with him.

Pang Xuelin frowned, there seemed to be such a person in his memory, but he had been in the wandering earth world for more than twenty years, and he had long forgotten many characters in reality, and he couldn't remember what this girl's name was.

"Oh, it's okay, I'm going out for dinner, let's go first!"

Pang Xuelin barely showed a smile, and then without saying a word, he walked directly past Qi Xin.

"Hey, what's wrong with this guy?"

Qi Xin turned around and looked at Pang Xuelin's back with some confusion, always feeling that Pang Xuelin was acting strangely.

When he came to the restaurant, all kinds of dazzling food almost dazzled Pang Xuelin, the Wandering Earth World as a whole was in a state of material shortage, even with Pang Xuelin's status, it was not that he could eat whatever he wanted.

Returning to the real world is like going back to heaven.

Pang Xuelin took a full two servings of various fruits and vegetables and meat, and it took half an hour to fill his stomach.

After eating, Pang Xuelin walked around the campus for a while.

Along the way, from time to time, you can see young students fighting, couples hiding in the corners whispering, night runners walking forward, and old professors taking leisurely walks...... Life is easy and comfortable.

Pang Xuelin secretly sighed in his heart, what a beautiful era!

After walking around the campus for more than an hour, Pang Xuelin slowly sorted out his memories in the real world and familiarized himself with the campus of Jiang University before returning to his residence.

Subsequently, Pang Xuelin took out his mobile phone and first called his grandparents and parents, for them, Pang Xuelin had not seen him for a few days, but for Pang Xuelin, he had not seen his relatives for more than 20 years.

Then, Pang Xuelin began to find some characters in the mobile phone address book that he had no impression.

He didn't return to China for a long time, and there were not many people in the address book, but Pang Xuelin saw a lot of familiar names.

Pang Xuelin, who is a big man like Yau Chengtong, Tao Zhexuan, Deligne, and Faltins, will naturally not forget, these people were all added to the address book by Pang Xuelin after the BSD conjecture report meeting.

Liu Tingbo also had the impression that he seemed to be the dean of the School of Mathematics of Jiang University.

It's just that who is this Qi Xin?

Pang Xuelin was slightly stunned, and the figure of the beautiful girl he had seen downstairs before suddenly appeared in his mind.

He pondered for a moment, flipped out WeChat, opened the circle of friends, and really found Qi Xin's selfie inside.

Then Pang Xuelin entered Qi Xin's circle of friends according to this account, and accidentally found a photo of himself and her in it.

In the photo, Qi Xin stood in front of him, posing with a cute scissor hand, while he stood behind him, smiling a little awkwardly.

The accompanying text is: On the first day of returning to school, I met the legendary professor Pang Xuelin, hehe, more approachable than I imagined, today thanks to his help to carry my more than 100 pounds of box to the eighth floor, otherwise I would have been a tragedy.

The dusty memories were slowly awakened, and all kinds of things about Qi Xin resurfaced in Pang Xuelin's mind.

"My relationship with her seems to be a little ambiguous, but I didn't pierce the last layer of window paper......"

Pang Xuelin's face showed a faint nostalgia and sadness.

After experiencing that sad relationship with Yao Bingxia in the wandering earth world, Pang Xuelin had no idea of falling in love in a short period of time.

"So how do you get along with her next?"

"Forget it, I don't want to think so much, let's take one step at a time!"

……

Pang Xuelin shook his head, put down his phone, and began to think about the next work plan.

Now, only by devoting oneself to one's work can one suppress the guilt and pain in his heart towards Yao Bingxia.

In the wandering earth world, he completed the construction of the Ponzi geometric theory system, and used this theory to give a general solution to the system of nonlinear partial differential equations in a general sense.

The exact solution of a nonlinear partial differential equation is for the numerical solution of such equations, and the general solution is the form in which the solution of the equation is obtained by some method, and the special solution is obtained after a specific initial boundary value condition is given.

However, at present, only simple hyperbolic equations, ellipses and other equations in the mathematical world can obtain such general and special solutions.

Most systems of nonlinear partial differential equations cannot be solved exactly, so Ponzi geometry is to systems of nonlinear partial differential equations what group theory is to solving equations.

But in the field of number theory, the value of Ponzi geometry has not yet been developed.

You must know that you came up with the Ponzi geometry theory in order to solve the ABC conjecture, who would have thought that in the wandering earth world, this theory unexpectedly played an unexpected role in solving nonlinear partial differential equations.

Over the years, I have been working mainly on the scientific committee in the Wandering Earth World, and I have no time to think about the ABC conjecture.

Now, it's time to think about addressing this.

Pang Xuelin thought for a moment, took out the manuscript paper, and entered the work state again.