Wie großartig ist Yang Zhenning tatsächlich?

Mr. Yang Zhenning, an academician of the Chinese Academy of Sciences, a Nobel laureate in Physics, and a theoretical physicist, passed away on October 18, 2025, at the age of 103.

Mr. Yang Zhenning was born on October 1, 1922, in Sanhe Town, Hefei, Anhui. His ancestral home is Fengyang, Anhui. His father, Yang Wuzhi, was a famous mathematician who studied in the United States in his early years and later served as a professor in the Department of Mathematics at Tsinghua University.

Since childhood, Yang Zhenning has shown extraordinary learning talent. When he was four years old, his mother began to teach him to read Chinese characters, and he mastered 3,000 Chinese characters in just over a year. During his childhood, Yang Zhenning achieved excellent results in both mathematics and Chinese.

In 1933, Yang Zhenning entered Beiping Chongde Middle School. It was in the small library of this middle school that he first came into contact with 20th - century physics. By reading the Chinese translation of James Jeans' The Mysterious Universe, Yang Zhenning developed a strong interest in special relativity, general relativity, and quantum mechanics. This accidental reading experience became an important enlightenment for him to embark on the path of physics.

In 1937, the Anti - Japanese War broke out. Yang Zhenning and his family endured a long and difficult journey of fleeing from war and arrived in Kunming in the spring of 1938. Due to the special situation during the war, the Ministry of Education allowed students who had not graduated from middle school to take the college entrance examination with equivalent educational qualifications. Against this background, 16 - year - old Yang Zhenning became one of the first freshmen at the National Southwestern Associated University.

Initially, following his father's advice, Yang Zhenning chose the Department of Chemistry. However, when he self - studied high - school physics textbooks in preparation for the entrance examination, he found that he was more enthusiastic about physics.

Shortly after the start of the semester, he obtained the consent of Professor Wu Youxun, the dean of the School of Science, and transferred to the Department of Physics.

A

Yang Zhenning's great life began from then on.

In 1942, Yang Zhenning obtained a bachelor's degree in science from the National Southwestern Associated University with an English thesis titled Group Theory and the Vibrations of Polyatomic Molecules. His supervisor was Professor Wu Dayou, a famous physicist. Subsequently, he entered the graduate school of the National Southwestern Associated University for further studies and conducted research on statistical physics under the guidance of Professor Wang Zhuxi. In 1944, he obtained a master's degree in science from the graduate school of Tsinghua University with his thesis An Inquiry into the Statistical Theory of Superlattices.

In 1945, Yang Zhenning won the Boxer Indemnity Scholarship to study in the United States and entered the University of Chicago to pursue a doctoral degree. Here, he was deeply influenced by physics masters such as Fermi. Under the guidance of his supervisor, Teller, he obtained a doctorate in physics in 1948.

In 1949, Yang Zhenning entered the Institute for Advanced Study in Princeton for post - doctoral research and began to collaborate with Li Zhengdao. This collaboration would leave a glorious mark in the history of physics.

Yang Zhenning's research in the field of physics covers multiple branches, including statistical mechanics, condensed matter physics, particle physics, and field theory. His work not only promoted the development of theoretical physics but also made a milestone - like contribution to the basic theoretical system of modern physics.

In 1944, Onsager published the exact solution of the two - dimensional Ising model on a square lattice, which was used to study the interaction of atomic magnetic moments in magnetic materials. Although Onsager's solution was complete, it did not directly give an important physical quantity: the spontaneous magnetization.

What is spontaneous magnetization? When a piece of iron is at a low enough temperature without an external magnetic field, the small magnets inside the iron will spontaneously align in an orderly manner, forming an overall magnetism. This phenomenon is called spontaneous magnetization. The spontaneous magnetization is a physical quantity that measures the strength of this overall magnetism.

In 1952, Yang Zhenning successfully extracted the exact formula for the spontaneous magnetization from Onsager's complex mathematical expression. Although it may not sound like much, it was extremely difficult mathematically. Since Onsager's solution involved complex integrals and infinite series, it was very difficult to extract the spontaneous magnetization from it.

After the publication of the paper, it attracted the attention of a physics giant - Einstein. He immediately sent his assistant, Kaufman, to invite Yang Zhenning to meet him.

Yang Zhenning was very honest. When recalling this meeting, he said that because he was too nervous and Einstein used a lot of German that he didn't understand, he actually "didn't gain much wisdom."

In addition, Yang Zhenning and his collaborators conducted a series of studies on the dilute Bose - gas many - body system and obtained the square - root correction term for the ground - state energy correction. This result was later confirmed by experiments.

B

Yang Zhenning's contributions in his life are far more than this.

In the 1960s, Yang Zhenning discovered the famous Yang - Baxter equation. The Yang - Baxter equation describes the consistency condition that must be satisfied during the scattering process of three particles in a quantum system.

Although the Yang - Baxter equation was discovered more than 60 years ago, it still provides a theoretical basis for the design of modern quantum computers. The reason why quantum computers can process a large amount of information simultaneously is that the interaction between quantum bits follows this special consistency law. Today's quantum encryption technology and future quantum computers all rely on the guidance of this equation.

The team of Bo Peng from the Pacific Northwest National Laboratory of the US Department of Energy constructed a quantum circuit with fewer layers by applying the Yang - Baxter equation, effectively reducing the noise problem of quantum computers without sacrificing accuracy.

In addition, this equation also plays an important role in statistical physics, helping scientists predict the collective behavior of a large number of particles. For example, it can explain why water freezes at a specific temperature and why magnets have north and south poles. It can be said that the Yang - Baxter equation is like a universal key in the quantum field.

In 1961, he and Byers applied the gauge - transformation technique to the condensed - matter system and theoretically explained the phenomenon of flux quantization in superconductors discovered by the Fairbank experimental group. In 1962, Yang Zhenning proposed the concept of non - diagonal long - range order, which provided an important theoretical framework for understanding macroscopic quantum phenomena such as superfluidity and superconductivity. These physical methods have been widely applied in the study of many problems in condensed matter physics.

However, Yang Zhenning's most well - known achievement is his groundbreaking work in particle physics. In 1956, Yang Zhenning and Li Zhengdao jointly proposed the theory of parity non - conservation in weak interactions. Before this, physicists generally believed that parity was conserved in all fundamental interactions, which was regarded as one of the basic symmetries of nature.

Parity is a concept in physics that describes spatial - reflection symmetry. Simply put, it is mirror symmetry.

This is a counter - intuitive study. In general perception, when a person stands in front of a mirror and raises their left hand, the person in the mirror raises their right hand, which is parity conservation. However, parity non - conservation means that something different happens in the mirror.

This study is one of the important bases for exploring the origin of the universe.

In the early stage of the Big Bang, an equal amount of matter and antimatter should have been produced. However, when they meet, they will annihilate into energy. Due to parity non - conservation, there is a slight difference in the decay behavior of matter and antimatter, which ultimately leads to a small "excess" of matter, forming today's stars, planets, and even humans. This entire process is called the "baryon - number origin."

Yang Zhenning and Li Zhengdao boldly proposed through in - depth theoretical analysis that parity might not be conserved in weak interactions. This hypothesis was later confirmed by Wu Jianxiong's experiment.

Due to this pioneering contribution, Yang Zhenning and Li Zhengdao jointly won the Nobel Prize in Physics in 1957. The award was entirely given to Yang Zhenning and Li Zhengdao to recognize their "penetrating research on the so - called parity law, especially the research leading to important discoveries regarding elementary particles."

However, many physicists believe that Yang Zhenning's greater contribution is the Yang - Mills gauge theory that he jointly proposed with Robert Mills in 1954. This theory is the foundation of modern gauge - field theory and the standard model of particle physics. It provides a unified theoretical framework for understanding the interactions between elementary particles.

The core idea of gauge - field theory is that the fundamental interactions in nature can be described by gauge symmetry. This symmetry requires that physical laws remain unchanged under a certain transformation, which is called a gauge transformation.

For example, we can measure temperature in Celsius or Fahrenheit. Although the numbers are different, water boils at 100 degrees Celsius and 212 degrees Fahrenheit, and this physical fact remains unchanged. A gauge transformation is similar to the conversion between Celsius and Fahrenheit, and gauge symmetry requires that physical laws should maintain the same form regardless of which "thermometer" is used.

In the microscopic world of particles, this symmetry is even more profound. It tells us that the electromagnetic interaction between electrons and protons, the strong interaction between quarks, and the weak interaction that causes radioactive decay can all be described by the same set of mathematical frameworks.

This is like discovering a universal "language" that can explain the unified laws behind seemingly completely different natural phenomena. It is this unity that enables scientists to predict the existence of new particles and finally discover them in experiments.

The influence of the Yang - Mills theory is far - reaching. It not only laid the foundation for the establishment of the standard model but also inspired the development of the electro - weak unification theory and quantum chromodynamics. As many as seven scientists have won the Nobel Prize for discovering new particles based on this theory, which is sufficient to illustrate its importance.

It can be said that without the Yang - Mills theory, there would be no modern particle physics.

Yang Zhenning's scientific achievements have been widely recognized by the international academic community. In addition to the Nobel Prize in Physics, he has also won the Fermi Award, the Wolf Prize, the National Medal of Science of the United States, and many other important awards. He is a member of many academic institutions, including the Chinese Academy of Sciences, the National Academy of Sciences of the United States, the Royal Society of the United Kingdom, and the Academia Sinica in Taiwan.

It is worth mentioning Yang Zhenning's contribution to the development of science in China. In 1971, Yang Zhenning became the first Chinese - American scientist to visit China after the relaxation of Sino - US relations. This visit was of great political and cultural significance at that time. Since then, he has visited China many times and actively promoted Sino - US scientific and cultural exchanges, making important contributions to the establishment of diplomatic relations and scientific cooperation between the two countries.

C

In 2015, Yang Zhenning resolutely gave up his US citizenship and returned to China to settle at Tsinghua University. He not only served as a professor at the Institute for Advanced Study at Tsinghua University but also held the position of honorary dean of the institute. He also personally taught physics courses to undergraduates, demonstrating his enthusiasm for education.

In 2016, Yang Zhenning changed his status from a foreign academician to an academician of the Chinese Academy of Sciences.

Yang Zhenning has raised more than 100 million yuan for the Institute for Advanced Study at Tsinghua University and has dedicated himself to attracting and cultivating top - notch scientific talents in China. His return to China is not only a personal choice but also reflects his deep patriotism.

As a great physicist who has spanned the centuries, Yang Zhenning has witnessed and participated in the development of modern physics. His scientific achievements have not only promoted human understanding of nature but also laid the foundation for the development of subsequent science and technology.

Yang Zhenning's life was a life dedicated to science, a life in pursuit of truth, and a life with a deep concern for his motherland.

In academic research, Yang Zhenning always maintained a rigorous scientific attitude and a keen physical intuition. He was good at grasping the essential problems from complex physical phenomena and conducting strict theoretical analysis using mathematical tools. His research methods and scientific thinking have influenced generations of physicists and pointed the way for the development of theoretical physics.

Yang Zhenning is not only an outstanding scientist but also an excellent educator. He has trained many excellent students and successors, and these talents have achieved important results in their respective research fields. He emphasizes the importance of basic - science education and advocates cultivating students' innovative thinking and independent research ability.

Looking back on Yang Zhenning's life, we see a true scientific giant. His scientific achievements will be forever recorded in the annals of human civilization, and his spiritual character will continue to inspire future generations.

Mr. Yang Zhenning's passing is a great loss to the Chinese scientific community and the international physics community. What he left us is not only a rich scientific heritage but also a precious spiritual wealth. He used his whole life to interpret what scientific spirit, patriotism, and the value of life are. His name will shine in the scientific sky forever, along with those of great scientists such as Newton and Einstein.

This article is from the WeChat public account "Zimubang" (ID: wujicaijing), written by Miao Zheng, and is published by 36Kr with permission.