In the next two months, in addition to teaching at the School of Mathematics of Peking University, Pang Xuelin also went to Wang Miao's nano center from time to time to learn about the manufacturing process and process of "flying blade" materials.

Of course, he can only look at the flowers and see a rough idea.

However, according to the process flow and technical data given by the system, Pang Xuelin finally figured out the principle of the "flying blade" material and the entire manufacturing process.

Unlike traditional carbon fiber materials, flying blade materials are made of carbon nanotubes.

Carbon nanotubes are considered to be one of the strongest materials found so far, with a Young's modulus of more than 1TPa, a tensile strength of more than 100 GPa (specific strength of up to 62.5 GPa/(g/cm3)), and more than 10 times the strength of T1000 carbon fiber.

You must know that the specific strength of macroscopic materials is far lower than 7.5GPa/(g/cm3), such as steel wire rope is 0.05~0.33GPa/(g/cm3), carbon fiber is 0.5~3.5GPa/(g/cm3), and polymer fiber is 0.28~4.14GPa/(g/cm3), so you can imagine how terrifying the strength of carbon nanotubes is.

However, when a single carbon nanotube material with excellent mechanical properties is prepared into a macroscopic material, its performance is often much lower than the theoretical value.

The main reason is that the carbon nanotubes forming fibers are all short in length, and the units overlap each other with van der Waals force, which is easy to slip under the action of tensile force, and cannot make full use of the intrinsic high strength of carbon nanotubes.

In addition, structural defects and stray orientation within carbon nanotubes can lead to a decrease in fiber strength.

Wang Miao used the preparation method of reaction black box to controllably prepare meter-level continuous ultra-long carbon nanotube bundles with definite composition, perfect structure and parallel arrangement, which had consistent orientation and mechanical properties close to the theoretical limit.

It is not only the best material for manufacturing space elevators, but also has bright application prospects in large aircraft, heavy launch vehicles, space stations, spaceships, super buildings and other fields.

The only regret is that even if this material is prepared in a black box, the annual production is extremely limited.

According to Wang Miao's estimates, the preparation cost of this material is almost equivalent to the same weight of gold.

Pang Xuelin couldn't help but be secretly speechless.

But he doesn't care, anyway, when he returns to the real world, the cost of flying blade materials will be left to his father to have a headache.

In the past two months, in addition to getting the flying blade materials, Pang Xuelin also held a BSD conjecture report meeting at the School of Mathematics of Peking University, which was attended by the world's top mathematicians.

Of course, Pang Xuelin didn't know anyone.

Therefore, Pang Xuelin was not stunned at the report meeting, and he regarded it as a rehearsal for the report meeting after returning to the real world.

In addition to some small flaws in the speech, Pang Xuelin answered the questions raised by the participating mathematicians one by one, and the proof of the BSD conjecture was officially recognized by the international mathematical community.

The advantage after this report meeting is that Pang Xuelin's status in the School of Mathematics of Peking University has been further improved, and several bigwigs of the Academy of Mathematics have also chatted with him, preparing to be elected as a candidate for academician of the Chinese Academy of Sciences of the Chinese Mathematical Society this year.

Pang Xuelin doesn't care about this, anyway, he has to go back after staying in the Three-Body World for a year or two, and these titles are the same with or without.

In the past two months, the friendship between Pang Xuelin, Wang Miao and Ding Yi has been further improved, and he even went to Wang Miao's house to eat a few times, and he gradually became familiar with Wang Miao's wife and children.

However, Pang Xuelin did not take the initiative to contact the important characters who will appear in the second and third parts of the novel, such as Luo Ji, although they are next door to Peking University, if Pang Xuelin takes the initiative to find them, he will definitely be able to find each other, but Pang Xuelin has no idea of meeting him.

On the one hand, when Luo Ji went to worship Yang Dong (Ye Wenjie's daughter) this summer, he met Ye Wenjie in front of the tombstone.

Ye Wenjie told him about two fundamental axioms of cosmic sociology:

Survival is the first need of civilization.

Civilization continues to grow and expand, but the total amount of matter in the universe remains the same.

In addition, the two concepts of chain of suspicion and technological explosion were also given, which laid the foundation for Luo Ji's later discovery of the law of the dark forest in the universe.

Pang Xuelin is sure that Luo Ji's every move is currently under the supervision of Zhizi.

And he put a set for the Three-Body Civilization and ETO, he didn't dare to guarantee whether the Three-Body Man was monitoring him, so going to Luo Ji at this time was purely looking for death.

But what Pang Xuelin didn't expect was that he didn't take the initiative to find the plot characters, but some plot characters took the initiative to appear in front of him.

That afternoon, Pang Xuelin had just finished teaching an abstract algebra lesson to undergraduates when his mobile phone rang.

Pang Xuelin looked at it and showed that it was Wang Miao calling.

He hurriedly pressed answer, and Wang Miao's hearty laughter came from the other end of the phone: "Xiao Pang, when you come to the house for dinner in the evening, your sister made a few good dishes." Dashi will come over then! “

"Okay, Brother Wang."

Pang Xuelin readily agreed.

and Wang Miao, Da Shi, Ding Yi and a few of them get together from time to time, which has almost become a fixed subject after he returns to China.

Among the four of them, Dashi's wife died early, Ding Yi has always been alone after Yang Dong's death, not to mention Pang Xuelin, Wang Miao has a family and a mouth, and she has a good life.

Therefore, they would go to Wang Miao's house from time to time to eat, and Wang Miao's wife Li Yao also recognized a sister and brother with him after knowing that Pang Xuelin was an orphan and did not have any relatives.

Several times during dinners, Li Yao also urged Pang Xuelin to hurry up and find a girlfriend to introduce Pang Xuelin to someone.

Pang Xuelin naturally declined, he didn't stay in this world for long, and finding a girlfriend would only delay the other party.

In the evening, Pang Xuelin drove to the downstairs of Wang Miao's house, picked up a small toy bought for Wang Miao's son from the passenger seat, entered the unit building, and knocked on Wang Miao's door.

After a while, the door opened.

To Pang Xuelin's surprise, it was not Wang Miao's wife Li Yao who opened the door, let alone Wang Miao or their son Wang Xiyu, but an extremely beautiful girl that Pang Xuelin had never seen.

Pang Xuelin has not seen beautiful women, but the girl in front of him, among all the women he has seen, ranks at least in the top three in terms of appearance and temperament.

It was even slightly higher than the Jiang University counselor Qi Xin he saw before he entered the Three-Body World.

The girl is wearing a white dress, her temperament is quiet and elegant, and when she smiles on her face, it seems that the whole world has become sunny.

"Hello, this is Wang ...... Professor Wang's house, right? ”

Pang Xuelin suspected that he had gone to the wrong room.

The girl nodded and said, "You are Professor Pang, come in!" ”

Pang Xuelin followed into the house, and Li Yao's voice came from the kitchen: "Little brother, you are here." ”

Immediately afterwards, Li Yao walked out of the kitchen with a plate of dishes, and said with a smile: "Little brother, let me introduce you, this is Zhuang Yan, the daughter of a colleague of mine, studying Chinese painting at the Central Academy of Fine Arts, Xiao Zhuang, this is Dr. Pang Xuelin I told you, the genius mathematician who solved the BSD conjecture!" ”

Pang Xuelin only felt a buzzing in his brain, Zhuang ...... Zhuang Yan? CAFA students?

The name is right, the school is right, and even the appearance is right!

No, Sister Li Yao, are you sure you want to introduce me to this heroine of "Dark Forest", Miss Zhuang Yan, who is responsible for the appearance in the trilogy?!