Yang in 2005
|Born||1 October 1922|
Chih-Li Tu ()
(m. 1950; her death 2003)
Weng Fan () (m. 2004)
|Doctoral advisor||Edward Teller|
|Other academic advisors||Enrico Fermi|
|Doctoral students||Bill Sutherland|
Yang Chen-Ning or Yang Zhenning (Chinese: ; born October 1, 1922) is a Chinese theoretical physicist who made significant contributions to statistical mechanics, integrable systems, gauge theory, and both particle physics and condensed matter physics. He and Tsung-Dao Lee received the 1957 Nobel Prize in Physics for their work on parity nonconservation of weak interaction. The two proposed that one of the basic quantum-mechanics laws, the conservation of parity, is violated in the so-called weak nuclear reactions, those nuclear processes that result in the emission of beta or alpha particles. Yang is also well known for his collaboration with Robert Mills in developing non-Abelian gauge theory, widely known as the Yang-Mills theory.
Yang was born in Hefei, Anhui, China; his father, Yang Wuzhi (; 1896-1973), was a mathematician, and his mother, Luo Meng-hua (), was a housewife. Yang attended elementary school and high school in Beijing, and in the autumn of 1937 his family moved to Hefei after the Japanese invaded China. In 1938 they moved to Kunming, Yunnan, where National Southwestern Associated University (Lianda), was located. In the same year, as a second year student, Yang passed the entrance examination and studied at Lianda. He received his bachelor's degree in 1942, with his thesis on the application of group theory to molecular spectra, under the supervision of Ta-You Wu. He continued to study graduate courses there for two years under the supervision of Wang Zhuxi, working on statistical mechanics. In 1944 he received his master's degree from Tsinghua University, which had moved to Kunming during the Sino-Japanese War (1937-1945). Yang was then awarded a scholarship from the Boxer Indemnity Scholarship Program, set up by the United States government using part of the money China had been forced to pay following the Boxer Rebellion. His departure for the United States was delayed for one year, during which time he taught in a middle school as a teacher and studied field theory.
From 1946, Yang studied with Edward Teller (1908-2003) at the University of Chicago, where he received his doctorate in 1948. He remained at the University of Chicago for a year as an assistant to Enrico Fermi. In 1949 he was invited to do his research at the Institute for Advanced Study in Princeton, New Jersey, where he began a period of fruitful collaboration with Tsung-Dao Lee. He was made a permanent member of the Institute in 1952, and full professor in 1955. In 1963, Princeton University Press published his textbook, Elementary Particles. In 1965 he moved to Stony Brook University, where he was named the Albert Einstein Professor of Physics and the first director of the newly founded Institute for Theoretical Physics. Today this institute is known as the C. N. Yang Institute for Theoretical Physics.
He retired from Stony Brook University in 1999, assuming the title Emeritus Professor. In 2010, Stony Brook University honored Yang's contributions to the university by naming its newest dormitory building C. N. Yang Hall.
He has been elected a Fellow of the American Physical Society, the Chinese Academy of Sciences, the Academia Sinica, the Russian Academy of Sciences, and the Royal Society. He was awarded honorary doctorate degrees by Princeton University (1958), Moscow State University (1992), and the Chinese University of Hong Kong (1997).
Yang visited the Chinese mainland in 1971 for the first time after the thaw in China-US relations, and has subsequently made great efforts to help the Chinese physics community rebuild the research atmosphere which was destroyed by the radical political movements during the Cultural Revolution. After retiring from Stony Brook he returned as an honorary director of Tsinghua University, Beijing, where he is the Huang Jibei-Lu Kaiqun Professor at the Center for Advanced Study (CASTU). He also is one of the two Shaw Prize Founding Members and is a Distinguished Professor-at-Large at the Chinese University of Hong Kong.
Yang married Chih-li Tu (Chinese: ; pinyin: ), a teacher, in 1950 and has two sons and a daughter with her: Franklin Jr., Gilbert and Eulee. His father-in-law was a Kuomintang General Du Yuming. Some scholars suspect that Du was promoted to a high-ranking position in Chinese People's Political Consultative Conference in order to convince Yang to return to China after seeking refuge in the US. Tu died in October 2003, but in December 2004 the then 82-year-old Yang made a controversial big news to the Chinese by marrying the then 28-year-old Weng Fan (Chinese: ; pinyin: ) who looks very like young Tu in appearance.
Yang became a U.S. citizen in 1964. He now resides in China, and he was granted permanent residency in mainland China in 2004. He renounced his U.S. citizenship as of Sep 30, 2015 and reclaimed his Chinese citizenship.
At The University of Chicago, Yang first spent twenty months working in an accelerator lab, but he later found he was not as good as an experimentalist and switched back to theory. His doctoral thesis was about angular distribution in nucleon reactions. Later he worked on particle phenomenology; a well known work was the Fermi-Yang model treating pion meson as a bound nucleon-antinucleon pair. In 1956, he and Tsung Dao (T.D.) Lee proposed that in the weak interaction the parity symmetry was not conserved, Chien-shiung Wu's team at the National Bureau of Standards in Washington experimentally verified the theory. Yang and Lee received the 1957 Nobel Prize in Physics for their parity violation theory. Yang has also worked on neutrino theory with Tsung Dao (T.D.) Lee, 1957, 1959, CT nonconservation (with Tsung Dao (T.D.) Lee and R. Oheme, 1957), electromagnetic interaction of vector mesons (with Tsung Dao (T.D.) Lee, 1962), CP nonconservation (with Wu Tai-tsun, 1964).
Yang is also well known for his collaboration with Robert Mills in developing non-Abelian gauge theory, widely known as the Yang-Mills theory. Subsequently, in the last three decades, many other prominent scientists have developed key breakthroughs to what is now known as gauge theory. In the 1970s Yang worked on the topological properties of gauge theory, collaborating with Wu Tai-tsun to elucidate the Wu-Yang monopole. Unlike the Dirac monopole, it has no singular Dirac string.
Yang has had a great interest in statistical mechanics since his undergraduate time. In the 1950s and 1960s, he collaborated with Tsung Dao (T.D.) Lee and Kerson Huang, etc. and studied statistical mechanics and condensed matter theory. He studied theory of phase transition and elucidated the Lee-Yang circle theorem, properties of quantum boson liquid, two dimensional Ising model, flux quantization in superconductors (with N. Byers, 1961), and proposed the concept of Off-Diagonal Long-Range Order (ODLRO, 1962). In 1967, he found a consistent condition for a one dimensional factorized scattering many body system, the equation was later named the Yang-Baxter equation, it plays an important role in integrable models and has influenced several branches of physics and mathematics.
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His birth date was erroneously recorded as September 22, 1922 in his 1945 passport. He has since used this incorrect date on all subsequent official documents.
When a reporter asked him: "Do you believe there is a Creator who creates all in the universe?" Professor Chen Ning Yang (1922- ), a Chinese Nobel Prize winner in physics in 1957, answered: "I think it is hard for me to directly say 'yes' or 'no'. I can only say that when we more and more understand the wonderful structures in the nature, no matter whether we directly or indirectly ask the question, there does exist the question you ask: is there someone or God who takes charge of all? I think it is a question that will never be finally answered. (The reporter asked: 'Is it because what man knows is too limited?') On one hand, yes; on the other hand, we can have a feeling that the universe will not be created so wonderful without an ultimate goal." Professor Yang held agnosticism here.