news

한어Русский языкEnglishFrançaisIndonesianSanskrit日本語DeutschPortuguêsΕλληνικάespañolItalianoSuomalainenLatina

This afternoon, among all the topics related to the Olympics, this one trended:

Nobel Prize winner in Physics Tsung-Dao Lee passed away at the age of 98.

For a time, domestic and foreign media outlets published articles to commemorate this legend in the field of physics.

Below the article, you can also see many netizens expressing their spontaneous condolences.

Anyone who knows a little about physics should know that both Tsung-Dao Lee and another physicist, Chen-Ning Yang,They are both textbook-level characters.

He won the Nobel Prize in Physics at the age of 31, proposed the theory of parity non-conservation, was the youngest full professor in Columbia University's 200-year history, proposed the creation of a junior class, and trained a group of physics talents for China. . . .

These achievements and contributions may only be written down as a few words, but they together make up Li Zhengdao's more than 60 years of physics career.

In 1926, Tsung-Dao Lee was born into a scholarly family in Shanghai. He showed extraordinary talent in mathematics and physics when he was young.

But the first half of Li Zhengdao's academic journey was not particularly smooth. It can even be said thatVery bumpy.

Due to the domestic situation at the time, Li Zhengdao did not complete elementary school and middle school. During this period, he moved to several places for refuge. Later, he was admitted to the Department of Electrical Engineering of Zhejiang University in Guiyang.

But at Zhejiang University, Li Zhengdao almost joined the Youth Expeditionary Force, but his teacher Shu Xingbei (one of the few physicists in China who studied quantum mechanics and relativity at the time) stopped him and said, "There are so many young people in China, anyone can join the army, except you, Tsung-Dao Lee."

Later, with the recommendation of Shu Xingbei, Li Zhengdao went to Southwest Associated University, where he met another mentor, Wu Dayou.

In 1946, Wu Dayou took Li Zhengdao to the United States. Li Zhengdao, who had not even graduated from college, relied on himself to obtain admission and scholarship to the University of Chicago.

That year, Tsung-Dao Lee was only 20 years old, but the next year he became a doctoral student under the "godfather" of physics, Fermi. He became acquainted with Chen-Ning Yang during his studies at the University of Chicago.

After graduating from his doctorate, Tsung-Dao Lee followed in the footsteps of Chen-Ning Yang and came to work at the Institute for Advanced Study in Princeton.

Thus began their brief but well-known period of academic collaboration.

Although he was a rookie, in the autumn of the year he took office, Tsung-Dao Lee and Chen-Ning Yang published an article on statistical mechanics, which even attracted Einstein.

It is said that at that time, Einstein personally expressed his interest in the research they were doing and talked to them for a long time.

Facts also prove thatThe old man's vision is indeed sharp.

Back in 1956, after a period of in-depth research, Yang Zhenning and Li Zhengdao published a paper in the American "Physical Review" and proposed the "Parity is not conserved" hypothesis.

At first glance, this term may not be clear to most people, but in the field of theoretical physics, it can be regarded as aChallenging cognitionThe law of.

You know, before this, scientists have always believed in "parity conservation". That is to say, the properties of a particle are the same whether it is its mirror image or itself.

The focus of Li and Yang's paper is to "bombard" this law.It is said that in the environment of weak interactions, the motion laws of particles and their mirror images are not necessarily exactly the same.

It's like your left hand and right hand, left foot and right foot, the movement mechanisms are different.

So at the beginning, many scientists were reluctant to believe this hypothesis. Even though Li and Yang presented evidence of "θ-τ" particles (all the characteristics are the same, but the decay mode is different), there are still many people who think this is an exception.

It was not until the following year that physicist Chien-Shiung Wu directly reproduced the “parity violation” using cobalt-60.The hypothesis has completely become an ironclad law.

According to Fermi, with the law of parity non-conservation, if aliens come, we can explain to them the left and right of human beings.

We can let it do a uranium-239 beta decay experiment, and then we can agree with the aliens that the spin direction of the emitted electrons is called "left".

By the way, Feynman also said that if it understands what we mean and extends the wrong hand when shaking hands, then we have to be careful because it may be made of antimatter.

Li Zhengdao and Yang Zhenning also won the Nobel Prize in Physics that year. At that time, Li Zhengdao was only 31 years old.He became the youngest Nobel Prize winner since World War II.

Nowadays, it is estimated that many people work for two to three years after graduating with a PhD. The value of this Nobel Prize naturally does not need to be boasted.

However, during his collaboration with Yang Zhenning, there was always a dispute over the ranking, and the subsequent Nobel Prize further fueled the fire.Parting ways。

As for who is right in this matter, from the current perspective, there is no need to argue.

Just like what Tsung-Dao Lee said in Broken Parity,Parity violation was the result of a generation of people in physics, and they were just two of many players.

Of course, that is what we say, but Li Zhengdao’s contribution to the academic world is real and cannot be ignored.

In addition to the Nobel Prize, there are also a large number of awards and honors of various sizes, including the Albert Einstein Award, the Galileo Medal, the New York Academy of Sciences Award, and so on.

If we say that the first half of Li Zhengdao's life was his personalPhysics researchThe highlights of his life can be seen in the following passages.EducationIn.

After the 1970s, Tsung-Dao Lee returned to China many times to give lectures and tried various ways to give back to domestic academic research.

He proposed to set up a junior class at USTC, suggested establishing a postdoctoral system, pushed for the establishment of the National Natural Science Foundation, and also presided over the China-US Joint Graduate Entrance Examination Program in Physics (CUSPEA).

Take the USTC Junior Class for example, how many talents have been cultivated. Data shows that USTC Junior Class has produced 5 academicians, and about 90% of the alumni have entered domestic and foreign educational and research institutions. (2018 data)

There is also the CUSPEA exam. Before this project came into being, if you wanted to study abroad, you could only rely on your family background, except for government-sponsored programs. TOEFL and IELTS were not available in China.

With CUSPEA, if you want to study abroad, you can take the exam and then pass the interview to study abroad smoothly.

In the eyes of Chinese students at that time, this path could even be called the "only way" to study abroad.

Moreover, even when he was far beyond the retirement age, Tsung-Dao Lee still couldn't sit still.

Around 2010, the old man, who was already in his eighties, was still active in the academic field and published seven papers in two years.

In 2014, when the Tsung-Dao Lee Library was established at Shanghai Jiao Tong University, Lee delivered a speech via video link and donated all the scientific literature and research manuscripts he had collected throughout his life, including the original Nobel Prize medal.

It was not until recent years that news about Tsung-Dao Lee gradually became less and less.

Therefore, whether in academic achievements or in education, Tsung-Dao Lee can be regarded as an outstanding scientist and a competent teacher.

Of course, this article I wrote is just a slice of Li Zhengdao's life.Like many great men in history, the page we casually turn over in a book may be the story of their magnificent life.

Anyway, RIP.

Written by: Song Qi & Xixi

edit: Jiang Jiang & Noodles

Art editor: Xuanxuan

Image, source：

Wikipedia, Feynman Lectures

Modern Physics Knowledge Magazine, Tsung-Dao Lee's Educational Journey

Sanlian Life Weekly, Tsung-Dao Lee and CUSPEA: Hope opportunities will come to more young people

Chinese Academy of Sciences, Tsung-Dao Lee: Studying is my lifelong pursuit

Tsung-Dao Lee, Broken Parity