I rely on talking to brush the copy

Outside the window came the sound of cicadas, the hot sun cast bright spots of light on the ground, the fan above the head squeaked and turned, and the warm heat wave blew the textbooks on the desk.

The summer of 1991 was also particularly hot.

Le Jing sat in the first row, very close to the old man who was standing on the podium and giving a lecture. The distance between the two was no more than one meter.

This was a solid state physics class at Tsinghua Graduate School. There were only about thirty people sitting in the huge lecture hall. Le Jing came to take the class.

The old woman on the stage was very old, with all her hair white. Because of long-term desk work, her back was a little hunched, but her eyes were still clear and moving, and her voice was still full of energy.

The classroom was very hot, and there was no fan on the podium. The old woman was sweating profusely, but she still tried to stand up straight and teach them in a loud voice.

Once, a student couldn't stand her standing for hours in class at such an old age, so he brought a stool for her to sit down, but she declined.

At that time, the old lady waved her hand, with a smile on her face that was unique to old-fashioned scholars. "When I was in school, the teacher stood in class. What does it look like to sit in class?"

At that time, Le Jing was sitting in the last row, looking at her quietly.

The old man standing on the stage was 79 years old, with white hair like snow. His name was Li Shuran. She was Li Jingran's sister, but not Li Jingran's sister.

And his name in this life was Chang Jingchen, a student who came to take classes for free.

He came to take classes for free two months ago.

In fact, he had mastered all the content of Li Shuran's lecture.

For this, we must thank the black technology from the future.

In the distant 26th century, brain-implanted learning chips have become popular. This means that people in the future do not need to study and memorize knowledge in class, but only need to implant relevant chips in the hippocampus area of ​​the brain, and people can read relevant knowledge.

If the human brain is regarded as a computer host, the learning chip is equivalent to a built-in storage card, which undoubtedly greatly shortens the learning time of future people.

But this does not mean that future people do not need to learn. They just remember this knowledge, and if they cannot understand it, they cannot use it. Just like a person who does not seek to understand it well, even if he memorizes the entire encyclopedia, he will only become an empty-brained endorsement machine.

So the role of the learning chip is to shorten the process of human brain memory. And its amazing function is that it is a permanent memory, which means that future people will never forget the knowledge in their brains.

Therefore, even if the system has implanted the learning chip into Le Jing's brain, and he has the knowledge of related subjects in his brain, he still needs to learn and understand so that he can use the knowledge.

And human energy is limited after all, and Le Jing cannot learn the knowledge of all subjects. Although he has a high IQ, he is not an omnipotent superman. So after careful consideration, Le Jing set his research direction as the development of rocket engines for manned spacecraft.

Fortunately, Le Jing is not stupid and can work hard, so after two years of systematic study, he has initially mastered the relevant theoretical knowledge.

Logically speaking, Le Jing's field of study had nothing to do with the materials science courses taught by Li Shuran. But he still came to attend classes on time every week.

As for the reason, Le Jing thought, he probably just wanted to see an old friend.

Even though he knew that this Li Shuran was not the Li Shuran in his memory, he still wanted to come and see.

He wanted to see with his own eyes what kind of person his once shy little sister had become.

Thinking about Li Shuran's life experience, Le Jing couldn't help but feel a lot of emotion.

Although he died, he left Li Shuran a lot of royalties as a legacy, and the copyright of his book would also be inherited by Li Shuran, and the royalties from the future reprints of the book would also be given to Li Shuran.

In other words, even if Li Shuran didn't work or get married, she could live a rich and stable life relying only on his legacy.

But Li Shuran didn't.

She studied hard. Then, seven years after his death, when she was 21 years old, she was admitted to the Department of Physics at Tsinghua University, and three years later, she went to study abroad at Princeton University in the United States.

She was 24 years old at the time, and her graduate and doctoral research direction was materials science in physics.

When the People's Republic of China was founded, she was 37 years old. At that time, she was already a doctoral student and assistant professor of materials science at Princeton University. Her mentor had planned to recommend her to be a lecturer. She was also married in the United States. Her husband was a classmate with the same ideals as her, and they had two lovely children.

Almost without any hesitation, she and her husband returned to China with their children. They abandoned all the favorable treatment in the United States and returned to the then impoverished New China to start from scratch.

In the 1950s and 1960s, the country began to secretly conduct nuclear bomb research. At that time, there was a lack of top physics talents and many important equipment in the country. Researchers could only use an abacus for calculations.

After careful consideration, Li Shuran resolutely chose to change her career and transferred from the Institute of Materials Science to the Institute of Atomic Energy. At the age of 48, she started to learn the relevant theoretical knowledge of controlled nuclear fusion from scratch. Li Shuran's choice was not uncommon at the time. Many of her colleagues changed their careers for the needs of the country. Because the needs of the country are their majors.

Later, she went to the northwest. I stayed there for nearly ten years.

After the two bombs came out one after another, Li Shuran, who was already 55 years old at the time, did not sit idle. She regrouped and re-entered the field of materials science that she loved, and made outstanding contributions to the subsequent launch of Dongfanghong-1.

Now, Li Shuran is 79 years old. This age should be the age for her to enjoy her grandchildren and family happiness, but if Li Shuran did this, she would not be Li Shuran who started studying nuclear physics at the age of 48.

The old lady has a dream in her mind, or it can be said to be an obsession - manned space flight.

The Soviets and Americans can do it, why can't the Chinese do it? One day, the Chinese will also be able to step into the stars of the universe.

So for more than ten years, the old lady has been conducting research on manned space flight.

In the little spare time left, she will return to her alma mater, Tsinghua University, to teach graduate students, hoping to cultivate more pillars for the motherland.

But the old lady probably doesn't know that Le Jing is actually her colleague.

The ding-ling-ling bell interrupted Le Jing's thoughts. Li Shuran put down her textbook and smiled kindly, "Classmates, get out of class is over. See you next week."

Le Jing took a deep look at the smiling old lady on the podium and suddenly smiled.

He thought, he no longer needs to come.

His little sister has become an amazing person. She has not wasted her life. She has been living a shining and hard life.

He put away his textbook, put on his schoolbag, and whispered to her like any ordinary student, "Goodbye, teacher."

Li Shuran was stunned for a few seconds, and when she saw the boy's light and gentle smile, a familiar feeling suddenly emerged in her heart.

"Wait a minute..." She couldn't help but ask, "Classmate, I've seen you a lot recently. Are you also a student of Tsinghua University?"

Le Jing shook his head, "No, I'm a student of USTC."

Li Shuran said earnestly, "My courses are quite advanced and not suitable for undergraduates. I recommend you to listen to the relevant courses taught by Professor Cheng Fang of your school."

Le Jing was startled, knowing that she had misunderstood, but he didn't explain.

After thinking for a while, he finally asked the last question: "Have you been doing well these years? Are you happy?"

This sentence was quite incoherent, and the question asked by the boy was also quite strange. Li Shuran stared at the boy's clear and gentle eyes like spring water. For some reason, her nose suddenly felt sour. This feeling came inexplicably, driving Li Shuran to give a serious and honest answer to the boy's question:

"I am doing well. I have lived a good life." With inexplicable urgency, she said to the boy in a hurry: "I have devoted all my life to the most magnificent cause in the world, and I have also witnessed the rise of this country with my own eyes. I am more convinced that this country will have a bright and brilliant future. In the future, I will continue to fight for the future and happiness of this country and nation. So I am very happy."

The boy smiled and nodded, and the look he gave her was gentle and warm, so familiar, just like a beautiful woman in the past.

Li Shuran seemed to have traveled through decades of vicissitudes and returned to that cool and gloomy autumn, and met the boy again.

August 24, 1926, she will always remember that day.

That morning, her brother, who had been bedridden for a long time, suddenly got up, put on new clothes, and said he was going out to visit friends.

At that time, her brother's health was already very bad, and he spent more than half of his time sleeping every day.

But that day, her brother was in a very good spirit, talked to her a lot, and laughed happily.

She was really happy at that time. She thought her brother was going to get better.

Before leaving, her brother smiled and told her, "I'm going out. After I leave, you go to my study. I left a letter for you on the desk."

At that time, she felt uneasy and asked with a forced smile: "Is there anything that brother can't say directly? Why do you still write to me?"

Her brother rubbed her head hard. She couldn't see her brother's expression clearly. She only heard him chuckle and answer: "Because my brother is very shy, there are some things that can only be told to you in the letter."

She was still too young at that time.

She ignored all the signs of danger and naively thought that her brother would recover soon and they would continue their warm and ordinary happy life belonging to mortals.

Then she watched her brother's back go away step by step. At that time, she suddenly felt a great sense of uneasiness, as if her brother was going to walk out of her world step by step.

She couldn't help shouting: "Brother, come back early, I'll wait for you at home."

Her brother didn't answer her, but turned sideways, with a gentle smile on his lips, waved to her, and then left without looking back, hurriedly and firmly, as if he was going to the battlefield of iron and fire.

... It seemed that he was telling her with his back that there was no need to chase.

This was the last time she saw her brother clean and refreshing, with a gentle smile.

From then on, she would always dream of her brother's bloody body and rotten body in her dreams at midnight.

The suicide note on the desk also became her inner demon. Every time she thought of it, she was always heartbroken and had difficulty falling asleep.

The unknown boy from another school turned and left. Looking at his back, Li Shuran suddenly felt a familiar panic and fear in her heart for some reason.

She asked loudly, "What's your name?!"

The boy paused, turned sideways, and smiled gently, "My name is Chang Jingchen."

He waved at her and said, "Goodbye, teacher."

Chang Jingchen...ah.

Li Shuran didn’t know what kind of answer she was expecting. She smiled bitterly and shook her head, waved back at the boy, and whispered to the boy and the determined figure in her memory: "...Goodbye."

The author has something to say:

I will recognize my sister!

I promise!

Sorry, I’m stuck today and updated half an hour late. I wanted to add more... but it’s too late today. I promise to add more tomorrow! ! ! If I don’t add more, I’ll be a dog!

Also, the prototype of Li Shuran’s experience after returning to China is Mr. Wang Chengshu. This female gentleman changed her career twice for the needs of the country. She re-learned nuclear physics related knowledge when she was over 50 years old. She is a very great person. Interested friends can Baidu the old gentleman’s life. The old gentleman lived a long life and died at the age of 82.

ps It seems that people who do physics are very long-lived 23333