Chen Ning Yang

Chen Ning Yang was born on October 1, 1922, in Hefei, Anhui, the eldest son of Yang Wu-zhi and Luo Meng-hua.⁠[1][2]

The Nobel Prize website spells his birthplace Hofei, Anhwei; the biography written at the time of the award and published on that website gives his parents’ names as Ke Chuan Yang and Meng Hwa Loh Yang and notes that he was also known as Frank or Franklin. The Royal Society’s record lists his parents as Luo Meng-hua and Ko-Chuen Yang, the latter described as a mathematician.⁠[3][4][5][6]

He adopted the name Frank in homage to Benjamin FranklinBenjamin FranklinBenjamin Franklin (January 17, 1706 – April 17, 1790) was a printer, publisher, scientist, diplomat, and statesman of colonial North America and the founding era of the United States, and one of the Founding Fathers of the United States. In Philadelphia he ran the Pennsylvania Gazette and published Poor Richard’s Almanack, founded the first lending library in North America, and proposed the school that later became the University of Pennsylvania; known for his electrical experiments and inventions such as the lightning rod, he served as the first Postmaster General of the United States, took part in drafting the Declaration of Independence, signed the treaty between the United States and France while in France, and signed the Treaty of Paris that ended the Revolutionary War.Open the full entry.⁠[7]

Sources differ on his date of birth: the Nobel Prize website, the American Institute of Physics’ record and the University of Chicago’s obituary give September 22, 1922; Physics Today, the account of his life issued by Tsinghua University and the chronology published by the Institute for Advanced Study at Tsinghua University, which he himself amended in 2010, give October 1; the Royal Society’s record lists both dates.⁠[3][8][9][10][2][1][6]

He was less than a year old when his father left for graduate study in the United StatesUnited StatesThe United States is a federal country in North America made up of 50 states, the District of Columbia as the seat of government, and territories such as Puerto Rico and Guam; its capital is Washington, D.C. The Continental Congress adopted the Declaration of Independence on July 4, 1776. The 2020 census (April 1, 2020) counted a resident population of 331,449,281, and the 435 seats of the House of Representatives are apportioned among the states on the basis of the census.Open the full entry in 1923, and he stayed with his mother in Hefei; in 1926 his mother began teaching him to read. In 1928 his father returned and the family went to Xiamen, where he entered the second grade of primary school and was taught English, arithmetic and Tang poetry by his father.⁠[1]

In 1929 his father was appointed professor in the mathematics department of Tsinghua University and the family moved to the university campus in Beijing, where he lived for eight years.⁠[2][1]

He entered the third grade at Chengzhi Primary School and, after graduating in 1933, boarded at Chongde Middle School. The Royal Society’s record says that he attended elementary school and high school in Beijing.⁠[1][2][6]

The chronology he revised records that in 1935, after reading The Mysterious Universe, he said to his parents that he would one day win the Nobel Prize, and that his father wrote on the back of a photograph of him that he seemed to be especially gifted. The People’s Daily article prints the inscription, in which his father also wrote that he intended to give him the courtesy name Bogui.⁠[1][11]

After the Marco Polo Bridge Incident of 1937 the family returned to Hefei, where he attended the second year of senior high school at Luzhou Middle School; Hefei was bombed in December of that year.⁠[2][1]

The family then traveled by way of Guangzhou, Hong Kong and Hanoi to Kunming, arriving in March 1938. A memorial page in the physics section of Stony Brook University’s website dates the family’s move to Kunming to 1939.⁠[1][12][13]

He first attended the eleventh grade at Kunhua Middle School and in the autumn of 1938 was admitted to National Southwest Associated University, formed by the merger of Tsinghua University, Peking University and Nankai University; he began in chemistry and then switched to physics.⁠[1][2]

His teachers there included C.Y. Chao, Y.H. Woo, Zhou Pei-yuan, Ta-You Wu and J.S. Wang, and his freshman course in Chinese literature was taught by Wen Yi-duo, Zhu Zi-qing and Wang Li.⁠[1]

In 1940 the courtyard of the family’s rented house in Kunming was hit in a Japanese air raid, and the family moved to Longyuan Village in the northwestern suburbs of Kunming.⁠[1]

Ta-You Wu introduced him to group theory. In 1942 he completed his bachelor’s thesis, “Group Theory and the Vibration of Polyatomic Molecules,” under Ta-You Wu and graduated from the physics department with a B.Sc.⁠[12][1][2][8]

The biography on the Nobel Prize website gives the title of this thesis as “Group Theory and Molecular Spectra.” The research profile of Tsung-Dao Lee published by the Lindau Nobel Laureate Meetings, for its part, calls Ta-You Wu the supervisor of his master’s thesis. CERN Courier’s obituary notes that he wrote that his taste in physics was already formed by his education in Kunming.⁠[4][5][14][15]

In 1942 he entered the graduate school of Tsinghua University, which had moved to Kunming during the war, and studied statistical mechanics under J.S. Wang; he received his M.Sc. in 1944 with the thesis “Contributions to the Statistical Theory of Order-Disorder Transformations.” The Royal Society’s record dates his M.Sc. to 1945.⁠[2][5][1][8][6]

In 1943 he sat the sixth Tsinghua examination for fellowships to study in the United States, and in 1944 he won the fellowship.⁠[1][2]

In 1945 he left China as a Tsinghua fellowship student, flew to Calcutta and, after waiting two months, sailed for the United States on an American troopship. The memorial notice of the C.N. Yang Institute for Theoretical Physics gives 1944 as the year he came to the United States for graduate study.⁠[1][2][7]

The chronology he revised states that he enrolled in the graduate school of the University of Chicago in late December 1945; the biography on the Nobel Prize website and the university’s obituary date his entry to January 1946.⁠[1][4][9]

He had been drawn to Chicago by its research atmosphere and the chance to learn from scientists including Enrico FermiEnrico FermiEnrico Fermi (1901–1954) was an Italian-American physicist who received the 1938 Nobel Prize in Physics and in 1942 led the team that achieved the first controlled nuclear chain reaction in Chicago.Open the full entry. He hoped to write an experimental thesis under Fermi, but Fermi’s laboratory at Argonne was not open to him; on Fermi’s recommendation he worked on theory with Edward Teller and on an accelerator experiment in the laboratory of Samuel K. Allison.⁠[9][12][1]

The experimental thesis did not succeed, and he later described himself as “clumsy in the laboratory.” Edward Teller encouraged him to turn a research idea into a dissertation, and in 1948 he received his Ph.D. with the thesis “On the Angular Distribution in Nuclear Reactions and Coincidence Measurements.” He added that “all my fellow graduate students laughed at me,” though they liked him as a person, especially because he could solve theoretical problems. The memorial page in the physics section of Stony Brook University’s website says that he graduated from the University of Chicago as the student of Edward Teller in 1949.⁠[1][9][5][8][13]

In 1946–1947 he was assistant to Enrico Fermi. He later recalled that Fermi taught him that “physics should not be a specialist’s subject.” In remarks to The New Yorker in 1962 he said that Enrico Fermi taught him that “physics is to be built from the ground up, brick by brick, layer by layer.”⁠[6][9]

Tsung-Dao Lee enrolled at the university in the autumn of 1946 and received his doctorate in 1950. Accounts differ on when and where the two first met: an article of 1982 by Paul Forman, curator for modern physics at the National Museum of American History, published on the website of the National Institute of Standards and Technology, says that they met in Kunming in 1944; a 2010 article in the magazine Oriental Outlook (Liaowang Dongfang Zhoukan) about Ji Cheng’s biography of Tsung-Dao Lee says that when Tsung-Dao Lee came to the University of Chicago in 1946 he was already a teaching assistant there and, on being notified by Ta-You Wu, had booked rooms for Tsung-Dao Lee’s party at the university’s International House, and that this was their first meeting; an article by Cao Kefan, printed in the book-excerpt pages of Guangming Daily in 2012, likewise says that the two met by chance at the University of Chicago in the autumn of 1946. The research profile of the Lindau Nobel Laureate Meetings says that Tsung-Dao Lee, while still a doctoral student, contributed to an important paper written in 1949 with him and M. Rosenbluth; Forman’s article places the beginning of their research collaboration in the early 1950s.⁠[12][9][16][17][18][14]

After his degree he served for a year (1948–1949) as an instructor in physics at the university.⁠[8][4]

In 1949, on the recommendation of Enrico Fermi and Edward Teller, he became a member of the Institute for Advanced Study in Princeton and a year later was reappointed for five years; he became a permanent member in 1952 and a professor in 1955.⁠[1][2]

At the Institute he worked alongside J. Robert OppenheimerJ. Robert OppenheimerJ. Robert Oppenheimer (1904–1967) was an American theoretical physicist and science administrator who directed the Los Alamos laboratory that developed the atomic bomb during World War II.Open the full entry. Stephen L. Adler’s retrospective quotes his recollection that J. Robert Oppenheimer informed him that he would propose to the Trustees that he be appointed his successor as director, and his reply: “It is quite uncertain that I shall make a good Director, while it is quite certain that I shall not enjoy the life of a Director.”⁠[9][12]

Before he moved to Stony Brook University he made a number of summer visits to Brookhaven National Laboratory, where several of his major discoveries were made.⁠[7]

In June 1951 he completed the calculation of the spontaneous magnetization of the two-dimensional Ising model; the paper “The Spontaneous Magnetization of a Two-Dimensional Ising Model” appeared in the Physical Review in 1952.⁠[12][19]

In the autumn of 1951 he resumed his collaboration with Tsung-Dao Lee, and their work on the lattice gas led to the unit circle theorem; in 1952 they published two papers in the Physical Review under the general title “Statistical Theory of Equations of State and Phase Transitions.”⁠[12][19][15]

While visiting Brookhaven National Laboratory he worked with his office-mate Robert L. Mills on non-Abelian gauge theory. Their papers “Isotopic Spin Conservation and a Generalized Gauge Invariance” and “Conservation of Isotopic Spin and Isotopic Gauge Invariance” appeared in the Physical Review in 1954.⁠[12][19]

The theory, later known as Yang–Mills theory, became one of the foundations of the Standard Model of particle interactions. Stephen L. Adler’s retrospective notes that the question of mass was emphasized in a critique by Wolfgang PauliWolfgang PauliWolfgang Pauli (1900–1958) was a Vienna-born theoretical physicist who received the 1945 Nobel Prize in Physics for the discovery of the exclusion principle, also called the Pauli principle, and who in 1930 proposed the neutral particle later named the neutrino; he was professor of theoretical physics at ETH Zurich from 1928 until his death.Open the full entry, who, it adds, had not published his own similar ideas, and that the quantization of the theory took two decades of work by a score of brilliant theorists to resolve.⁠[20][21][12]

Physics World’s obituary dates the proposal of the theory to 1953.⁠[22]

In the same year Hideki Yukawa left Columbia UniversityColumbia UniversityColumbia University, formally Columbia University in the City of New York, is a private research university in New York City and a member of the Ivy League. Founded in 1754 by royal charter from King George II as King's College, it is the oldest institution of higher education in New York State and the fifth oldest in the United States. It was renamed Columbia College in 1784 and adopted the university name and moved to Manhattan's Morningside Heights in 1896. It has 17 schools and four affiliated colleges, with 35,978 students enrolled in fall 2025. Legal scholar Jennifer L. Mnookin became president on July 1, 2026.Open the full entry for Japan and Columbia University invited him to succeed Yukawa, which he declined; in the autumn of 1955 the University of Chicago offered him Enrico Fermi’s professorship at a high salary, which he also declined.⁠[1]

In 1956 he gave the concluding report on high-energy physics at the Rochester International Conference, in which he discussed the θ–τ puzzle.⁠[1]

In the spring of that year he and Tsung-Dao Lee critically examined the experimental evidence for parity conservation. They found that for weak interactions the assumption of right–left symmetry had no experimental support, because the existing experiments would have given the same result whether or not the assumption held.⁠[16][23]

On June 22, 1956, the editor of the Physical Review received their paper “Question of Parity Conservation in Weak Interactions,” which questioned whether parity is conserved in weak interactions and suggested experiments to test it; he was then 33 and Tsung-Dao Lee 29. The paper appeared in volume 104 of the journal (1956).⁠[16][19]

One test they proposed was to align the spins of radioactive nuclei and compare the numbers of electrons emitted along and against the direction of the spin.⁠[16]

Chien-Shiung WuChien-Shiung WuChien-Shiung Wu (1912–1997) was a Chinese-born American experimental physicist who spent most of her career at Columbia University and worked on the Manhattan Project. Her cobalt-60 beta-decay experiment of 1956–1957, carried out with collaborators, provided the first experimental proof that parity is not conserved in weak interactions.Open the full entry and her collaborators carried out the first of the experiments they had proposed, measuring the direction of the electrons emitted in the beta decay of radioactive cobalt nuclei placed in a magnetic field; the result showed that parity is not conserved in beta decay.⁠[23][1][3]

In the same year he, Tsung-Dao Lee and Reinhard Oehme published “Remarks on Possible Noninvariance Under Time Reversal and Charge Conjugation,” which dealt with the time-reversal, charge-conjugation and parity symmetries and the neutral K meson system; he and Tsung-Dao Lee also published “Parity Nonconservation and a Two-Component Theory of the Neutrino.”⁠[19][12]

In the summer of 1957 he, his wife and his eldest son spent six weeks with his father in Geneva, Switzerland; CERN Courier’s obituary states that this was the first meeting of father and son since he had left for Chicago and that it took place at CERN. In the summers of 1960 and 1962 he met his parents in Geneva twice more. The chronology calls the 1957 meeting an emotional reunion; in 1960 his wife, his second son Gilbert and his brother Chen Ping Yang went to Geneva with him, and in 1962 Chen Ping Yang and Gilbert. Stephen L. Adler’s retrospective quotes him as saying that at the reunions of 1960 and 1962 his father felt “a sense of responsibility to convince me to go back to China.”⁠[1][15][12]

On December 10, 1957, he and Tsung-Dao Lee were jointly awarded that year’s Nobel Prize in Physics, each receiving one half, “for their penetrating investigation of the so-called parity laws which has led to important discoveries regarding the elementary particles.” At the time of the award he was affiliated with the Institute for Advanced Study.⁠[1][3]

The presentation speech was given by O.B. Klein, a member of the Nobel Committee for Physics. On December 11 he delivered his Nobel Lecture, “The Law of Parity Conservation and Other Symmetry Laws of Physics.”⁠[23][24]

In his speech at the Nobel banquet he said that he was proud of his Chinese heritage and background and equally devoted to modern science.⁠[1][25]

Tsinghua University’s obituary describes the two as the first Chinese Nobel laureates; CERN Courier’s obituary calls them the first Nobel laureates of Chinese origin.⁠[21][15]

In the same year he received the Albert Einstein Commemorative Award and was named one of the outstanding young men of 1957 by the U.S. Junior Chamber of Commerce; in 1958 Princeton UniversityPrinceton UniversityPrinceton University is a private university and Ivy League member in Princeton, New Jersey. Chartered on October 22, 1746 as the College of New Jersey, it moved to Princeton in 1756 and adopted its present name in 1896. Undergraduate education leads to A.B. and B.S.E. degrees and emphasizes small-group discussion, independent research and residential college life. Graduate education spans the humanities, social sciences, natural sciences and engineering. As of October 2026, Christopher L. Eisgruber was president. Its 2026–27 operating budget was $3.407 billion, including $342 million for undergraduate aid.Open the full entry awarded him an honorary D.Sc.⁠[4][26]

In 1959 he was elected to the American Academy of Arts and Sciences.⁠[27]

In 1961 he and N. Byers published “Theoretical Considerations Concerning Quantized Magnetic Flux in Superconducting Cylinders” in Physical Review Letters, and in 1962 he published “Concept of Off-Diagonal Long-Range Order and the Quantum Phases of Liquid He and of Superconductors” in Reviews of Modern Physics.⁠[19]

In 1962 his collaboration with Tsung-Dao Lee came to an end; the two had written dozens of papers together.⁠[1][9]

As to the year their collaboration ended, he twice dates the parting and the break to 1962 in his article of 2010, while the research profile of Tsung-Dao Lee published by the Lindau Nobel Laureate Meetings says that it “suddenly broke up” in 1961. An article by Cao Kefan, printed in the book-excerpt pages of Guangming Daily in 2012 from his book Beihuan Zichou (Shanghai Bookstore Publishing House, 2011), relates that J. Robert Oppenheimer once thought the most beautiful sight in the world was him and Tsung-Dao Lee walking side by side on the lawn at Princeton. The Oriental Outlook article gives the remark in different words: J. Robert Oppenheimer once said that Tsung-Dao Lee and he, sitting on the lawn of the Institute for Advanced Study in Princeton discussing problems, made a delightful sight. Each side has given its own account of how and why they parted.⁠[28][14][18][17]

There are two accounts of the disagreement over the order of their names. An article of 2010 in the magazine Oriental Outlook (Liaowang Dongfang Zhoukan) presents the biography of Tsung-Dao Lee by Ji Cheng, published by the International Culture Publishing Corporation, and identifies its author as a son of Ji Xianlin. In the biography’s account, when the two wrote two papers on statistical mechanics in the autumn of 1951 he proposed that, if Tsung-Dao Lee did not mind, his own name should come first, as he was four years older, and on the second paper Tsung-Dao Lee persuaded him to change the order in line with international practice; in 1957 he asked that at the presentation of the prize he receive it ahead of Tsung-Dao Lee in order of age, and Tu Chih-li wished to be escorted by the King on entering the banquet. In his article of 2010 replying to the biography he writes that to sign both papers Yang–Lee would have been the normal order, that he had at first even planned to put Tsung-Dao Lee first on both, and that it was only because he partly accepted Tu Chih-li’s advice that one paper was signed Yang–Lee and the other Lee–Yang; the article does not discuss the order at the prize ceremony.⁠[17][28]

His side’s account of 1962 is given in Cao Kefan’s article. It relates that when Jeremy Bernstein proposed to write an article for The New Yorker about the two men’s collaboration, he had misgivings, feeling that Jeremy Bernstein was closer to Tsung-Dao Lee and fearing that the article would overpraise Tsung-Dao Lee or even distort history, and that he therefore asked J. Robert Oppenheimer to try to stop its publication. The article quotes his own recollection: on April 18, 1962, he and Tsung-Dao Lee had a long talk in Tsung-Dao Lee’s office and went over everything that had happened since 1946; as when a conflict within a family is reconciled, it was a process of emotional release, and both felt the relief that follows; but the reconciliation did not last, and a few months later they parted for good.⁠[18]

Tsung-Dao Lee’s side’s account is given in Ji Cheng’s biography. As summarized in the Oriental Outlook article, on May 12, 1962, The New Yorker published Jeremy Bernstein’s article on how the two had come to discover parity nonconservation; when Tsung-Dao Lee received the proofs in April he made few changes, but he raised many objections, saying that parts of the article were painful, asking that in some places his name be put before Tsung-Dao Lee’s, and asking that Tu Chih-li’s name be put before that of Tsung-Dao Lee’s wife, as Tu Chih-li was a year older; the next day he came to Tsung-Dao Lee’s home and asked that wherever the article said “Lee and Yang” a note be added explaining that the order was alphabetical, and that evening he telephoned to say that the notes might be dispensed with but that the article should read “Yang and Lee” throughout. Tsung-Dao Lee found the requests tiresome and, disappointed, proposed that they no longer work together. The biography says that he then became very agitated and began to cry, saying that he very much wanted to continue the collaboration, and that in the end the two agreed to suspend it. In November of that year Tsung-Dao Lee handed a letter of resignation to J. Robert Oppenheimer, who, by the biography’s account, greatly regretted this and remarked sharply that Tsung-Dao Lee should give up high-energy physics and that he should see a psychiatrist. The Oriental Outlook article notes that this is only Tsung-Dao Lee’s side’s account and that Ji Cheng tried to include his statements in the biography for balance.⁠[17]

Cao Kefan’s article also quotes Tsung-Dao Lee’s account that he became emotional at the time and began to weep, saying that he very much wanted to work with Tsung-Dao Lee; it likewise records J. Robert Oppenheimer’s remark, listing it among the reactions of physicists who knew both men after the break, without saying to whom or when it was made. In the same account, as Cao Kefan quotes it, Tsung-Dao Lee relates that in June of that year, when Leon Lederman, Melvin Schwartz and Jack Steinberger were about to publish their experimental results on a second kind of neutrino, he once again became very anxious and was worried about the order in which their paper mentioned the two men’s names; that, much to Tsung-Dao Lee’s surprise, he then wrote Tsung-Dao Lee several letters that were extremely unpleasant and full of hostility; and that Tsung-Dao Lee felt very sad about all this and realized that their friendship no longer existed. This is Tsung-Dao Lee’s side’s account only. His own account of the 1962 conversation is the long talk of April 18 and the reconciliation and parting that followed, as given above; his article of 2010 replying to Ji Cheng’s biography rebuts a number of its statements section by section but does not mention the weeping or J. Robert Oppenheimer’s remark, nor does it describe how the break came about. Chen Fangzheng, a scholar at the Chinese University of Hong Kong, traces the falling-out roughly to Jeremy Bernstein’s article.⁠[18][28][29]

On March 23, 1964, he became a citizen of the United States, nineteen years after arriving in the country. In remarks published by Xinhuanet in 2017 he said that he had considered the decision for a long time and that it was a very painful one, and that in a book of 1983 he had written that his father, to the end of his life, did not forgive him for giving up Chinese citizenship.⁠[30][1]

In the same year, at the invitation of The Chinese University of Hong Kong, he gave a public lecture on his parity work in the newly opened Hong Kong City Hall and spent time in Hong Kong with his parents, his brother Zhen-han and his sister Chen-yu; thereafter he lectured at the university frequently.⁠[1][31][32]

After the discovery of CP violation in 1964 he and Tai Tsun Wu made a phenomenological analysis of neutral kaon decay, published in Physical Review Letters as “Phenomenological Analysis of Violation of CP Invariance in Decay of K0 and K0-bar.”⁠[12][19]

In 1965 he was elected a member of the National Academy of Sciences and chaired the Panel of Theoretical Physics of its Physics Survey Committee.⁠[8][1]

In 1964–1965 New York StateNew York (state)New York is a state in the eastern United States; its capital is Albany and its largest city is New York City. One of the original 13 states, it ratified the U.S. Constitution on July 26, 1788, becoming the 11th state to join the Union, and its population in the 2020 census was 20,201,249.Open the full entry created the Einstein Professorships, and the State University of New York at Stony Brook (Stony Brook University) invited him to head an institute of theoretical physics; he accepted around the end of April 1965. On November 12, 1965, the appointment was front-page news in The New York TimesThe New York TimesThe New York Times is an American morning daily newspaper published in New York City. Founded in 1851, it is published by The New York Times Company.Open the full entry. Stephen L. Adler’s retrospective quotes his later reflection: “The ivory tower is not the world, and the challenge to help build a new university is exciting.”⁠[12][1]

In 1966 he left Princeton to become Albert Einstein Professor of Physics at the university and founding director of its newly established Institute for Theoretical Physics, posts he held until 1999; it was the longest academic appointment of his life. The memorial page in the physics section of Stony Brook University’s website says that in 1966 he moved with his family to the State University of New York at Stony Brook, then still very much under construction, and that he helped guide the development of the Department of Physics, later the Department of Physics and Astronomy.⁠[1][7][8][13]

Physics World’s obituary and the Royal Society’s record date his move to 1965. The Simons Foundation’s obituary, for its part, calls him the inaugural head of the physics department at Stony Brook University and says that he worked there from 1965 until his retirement in 1999.⁠[22][6][33]

He assembled the institute’s original faculty. In her 2025 memorial message, Stony Brook University’s president, Andrea Goldsmith, wrote that he “took a chance on coming to Stony Brook when we were still a young university.” The institute’s memorial notice recalls his remark that in a way he “grew up with Stony Brook.”⁠[7][34]

In 1966 he and his brother Chen Ping Yang published a series of papers on the one-dimensional chain of anisotropic spin–spin interactions, including a proof of Bethe’s hypothesis for the ground state.⁠[19][12]

In 1967, while solving the one-dimensional many-body problem with a repulsive delta-function interaction, he found a key equation, published in Physical Review Letters as “Some Exact Results for the Many-Body Problem in One-Dimension with Repulsive Delta Function Interaction”; in 1972 Baxter found a similar equation, and it later became known as the Yang–Baxter equation.⁠[1][19][2]

The account of his life issued by Tsinghua University judges that the equation opened new directions in statistical physics and low-dimensional quantum theory.⁠[2]

In 1969 he and Chen Ping Yang applied the Bethe ansatz to a one-dimensional system of bosons with a repulsive delta-function interaction and published “Thermodynamics of a One-Dimensional System of Bosons with Repulsive Delta-Function Interaction.”⁠[12][19]

The chronology he amended records that in 1967, after the Cultural Revolution broke out in China, his father, Yang Wu-zhi, was criticized and denounced; he lost contact with his father and could know that his father was still alive only by seeing his signatures on cheques drawn on their joint bank account in Switzerland.⁠[1]

Chen Fangzheng traced the course of the dispute in the newspaper Southern Weekly (Nanfang Zhoumo) in 2011. He writes that in 1970 Tsung-Dao Lee lectured on the history of weak interactions at a school in Erice and that listeners had the impression he was not mentioned at all (his own article of 2010 likewise dates the lecture to 1970 and says that he came upon its text, in a book published in 1971, only ten years later); that at a conference in Conghua, Guangdong, in January 1980 he and Tsung-Dao Lee sat on either side of the chairman without speaking to each other; that in 1983, in the commentary to his Selected Papers 1945–1980 With Commentary, he explained that, apart from his closest relatives, he had meant to keep silent about all this for ever, but that in 1980 he had come upon the text of Tsung-Dao Lee’s Erice lecture, realized that Tsung-Dao Lee was deliberately distorting that history (“implied and insinuated various things”) and so felt he had to tell the truth; that three years later Tsung-Dao Lee issued as a preprint an essay that Chen Fangzheng calls “Broken Symmetry,” later included in his selected papers of 1986 (his own article of 2010 gives the title of Tsung-Dao Lee’s 1986 essay as “Broken Parity”); that a biography of him by Chiang Tsai-chien appeared in 2002 from Commonwealth Publishing (Tianxia Yuanjian) in Taipei, whose author states in a postscript that Tsung-Dao Lee ignored the author’s request for an interview because the author had opposed Tsung-Dao Lee’s effort to have Taiwan join an American high-energy collider project; that on April 3, 2003, Tsung-Dao Lee gave an interview to Yang Xujie of the Beijing newspaper Science Times (Kexue Shibao), which, with related documents, first circulated in photocopy and was published in 2004 by Gansu Science and Technology Press and by Cosmos Books in Hong Kong; and that after Ji Cheng’s biography appeared in 2010 he was compelled, in March and April of that year, to publish a reply simultaneously in the Hong Kong bimonthly Twenty-First Century and the Beijing China Reading Weekly.⁠[29][28]

His own account is that the breakthrough was his. In his article of 2010 he writes that after he presented a result at Brookhaven National Laboratory in May 1956, Walter Selove asked him why so many terms canceled; unable to answer at once, he thought hard for a day or two and, on a day around the middle of May, suddenly saw that the concept of the pseudoscalar had to be introduced to understand it. To the question whether the insight was his or Tsung-Dao Lee’s he answers that it was his, adding that he has no ironclad proof but proof that he rates as 80 to 90 percent credible. He writes that he wrote the first draft of the 1956 paper around the end of May, and that it was typed as Brookhaven document 2819 and sent to the Physical Review on June 22; he notes that the 2004 collection and Ji Cheng’s biography say instead that Tsung-Dao Lee wrote the draft at Columbia University, concedes that no document at hand can settle the point with complete certainty, and asks whether, had Tsung-Dao Lee written the draft, Tsung-Dao Lee would have raised no objection in his reply of 1986, which he calls the most important response of Tsung-Dao Lee’s life. He further writes that Murray Gell-Mann, believing for a time that their paper contained an error, hurriedly wrote a short paper and sent it to him with a note on its first page asking for his opinion before it went to press, and a few days later, having found that their paper was not wrong after all, wrote to withdraw it; although their paper had been published with the names in the order Lee–Yang, Gell-Mann’s short paper cited it throughout as Yang–Lee, never as Lee–Yang; he holds that the version in which Tsung-Dao Lee led and he assisted strangely reverses who was the principal and who the secondary partner, contrary to the impression of colleagues at the time. He also writes that Tsung-Dao Lee had spoken about these events in lectures in several places between 1968 and 1971, whereas he himself made no public reply until 1983. The Oriental Outlook article quotes a postscript he wrote in 1982 to his essay on how the prize-winning paper came about: their discussions centered on the θ–τ puzzle, and at a crucial point it occurred to him that the symmetry of the production process should be separated from that of the decay process; Tsung-Dao Lee at first opposed the idea, and after he tried to persuade him, later agreed.⁠[28][17]

The article of 2010 also replies, section by section, to other statements in Ji Cheng’s biography. On his doctoral thesis of 1948 he writes that he was already working on the problem before he talked with Tsung-Dao Lee, and that instead of doing extensive calculations he tried to understand why so many terms canceled. On Enrico Fermi he writes that he was indeed not Fermi’s doctoral student and Tsung-Dao Lee was, but that he was Fermi’s favored student and Tsung-Dao Lee was not; as evidence he cites that of the many students Fermi taught in his nine years at Chicago he alone published a theoretical paper jointly with Fermi; the discussions of Julian Schwinger’s work on renormalization that Fermi held in his office two or three mornings a week in the spring of 1948; Fermi’s often asking him, and never Tsung-Dao Lee, to teach in his place when traveling; his visit to Fermi in hospital; and Emilio Segrè’s request that he write for Fermi’s collected papers. On a paper of 1955 by the two men he writes that, far from refuting his 1954 paper with Robert L. Mills, it extended it. On CUSPEA he writes that he never said such things on any occasion, never wrote such a letter and never opposed the program in any way, which Tsung-Dao Lee initiated and led in the early 1980s and of which he always approved; Stony Brook University did not take part because it had other channels for Chinese graduate students and because he felt he could not work with Tsung-Dao Lee. The statements he is answering, as his article quotes them, say that a letter to the Chinese government headed by a very famous Chinese-American physicist protested against CUSPEA and forced the program to halt midway, and that the letter applied to CUSPEA Cultural Revolution–style labels, calling it a forfeiture of sovereignty and a national humiliation, worse than the semi-colonial China of the late 19th and early 20th centuries. The Oriental Outlook article, presenting Ji Cheng’s biography, sets this among broader claims. It relates that there had long been differing views in China on the development of high-energy physics and that, once the two Chinese-born laureates began visiting China and became involved, the differences took on a strong coloring of personal pique; it gives as examples that Tsung-Dao Lee advocated building a high-energy accelerator and he opposed it, that Tsung-Dao Lee urged attention to basic science and he pressed for applied science, and that Tsung-Dao Lee created a special examination to help Chinese students go to study in the United States and he called it a forfeiture of sovereignty and a national humiliation. It quotes the biography as saying that he made no concrete proposal for the development of high-energy physics in China, even advocated freezing the funding of basic research, saying that this was in the interest of the whole nation, and held that the Academy of Sciences should concentrate on developmental research and put production first. It quotes Ji Cheng as writing that, by extension, it seemed that whatever Tsung-Dao Lee favored he opposed; that his personal pique extended far beyond high-energy physics and its source lay entirely with him; that Tsung-Dao Lee, by contrast, showed no personal pique about what he did after returning to China; and that no one could see a pattern of Tsung-Dao Lee opposing whatever he proposed. These are statements of Tsung-Dao Lee’s side as the biography presents them. The article ends by calling his collaboration with Tsung-Dao Lee in 1946–1957 very, very successful, recalling that he had once said it was admired and envied by their colleagues at the time, and closes by quoting Abraham Pais to the effect that understanding the truth of the matter requires more knowledge of Chinese tradition than Pais had.⁠[28][17]

Tsung-Dao Lee’s account is that the breakthrough in thinking on parity nonconservation was made by Tsung-Dao Lee alone in early April 1956 and had nothing to do with him; Tsung-Dao Lee said so in answering the Science Times in 2003, and both Chen Fangzheng’s article and his own article of 2010 quote the statement. An article of 2010 by Pan Chen in the magazine Bolan Qunshu quotes Tsung-Dao Lee in the 2004 collection as saying that he joined in only in May and that in early May 1956 Tsung-Dao Lee accepted his request and agreed to work with him; it also cites Tsung-Dao Lee’s recollections of 1988, in which Jack Steinberger called on Tsung-Dao Lee one day in early May, he drove from Brookhaven to Columbia University the next morning and the two discussed the matter intensely all day, and Tsung-Dao Lee then went to see Chien-Shiung Wu, who lent him an authoritative book on beta decay; and Tsung-Dao Lee wrote twice in the collection that both of them had raised the possibility of parity nonconservation at the Rochester conference of 1956. Cao Kefan’s article states that the real focus of their conflict was not only the order of names but who first independently proposed the breakthrough idea of parity nonconservation, and gives Tsung-Dao Lee’s position as being that the breakthrough was made by Tsung-Dao Lee alone in early April 1956 and that he joined in only in May.⁠[29][28][35][18]

Chen Fangzheng does not rule for either man. He writes that the dispute cannot be settled by compromise and that in the end right and wrong must still be decided, but that this will very probably come only when circumstances have changed and none of it matters any more, and not at a time that he and his contemporaries will see; he recalls the dispute between Newton and Leibniz over the invention of the calculus, asks whether the dispute between Tsung-Dao Lee and him can be seen in the same light, and answers that he dare not say and that he thinks the two of them would probably not agree. Pan Chen’s article argues his side: it holds that Tsung-Dao Lee’s three retrospective pieces of 1971, 1986 and 1988 all put in May 1956 the point at which Tsung-Dao Lee understood that the pseudoscalar should be studied; it notes Chien-Shiung Wu’s recollection of 1972 that Tsung-Dao Lee came to her office one day in the early spring of 1956 and argues that this refers to early May, pointing out that New York weather records show 10 centimeters of snow in the city in April 1956 and an average temperature below 12°C; it cites a recollection of 1988 by Schwartz that the data, divided and analyzed again at Tsung-Dao Lee’s suggestion, did not suffice for any conclusion; and it states that the record of the Rochester conference contains no remark by Tsung-Dao Lee raising the possibility of parity nonconservation, whereas the proceedings show that he raised it there. Pan Chen concludes that Tsung-Dao Lee’s arguments that the parity question was solved chiefly by Tsung-Dao Lee do not agree with the facts recorded in earlier documents.⁠[29][35]

An article by Chiang Tsai-chien published in the China Reading Weekly in 2007 relates that in April 2006 a symposium marking the 50th anniversary of parity nonconservation, organized by N. Koller, a former student of Chien-Shiung Wu, was held in Dallas, TexasTexasTexas is a U.S. state in the south-central United States, with its capital at Austin and its largest city Houston. It was admitted to the Union on December 29, 1845, as the 28th state, and the 2020 census (April 1, 2020) counted 29,145,505 residents.Open the full entry; Chien-Shiung Wu’s son Yuan Weicheng, also a physicist, spoke there on his mother’s life and work, and Tsung-Dao Lee and Leon Lederman also gave talks. On April 22, 2006, he and Tsung-Dao Lee, once close collaborators who had later quarreled and broken with each other, met at the symposium. Tsung-Dao Lee spoke first, on some neutrino research and on Chien-Shiung Wu and her experiment, without touching on his former collaboration with him; Leon Lederman then spoke on another experiment he had carried out at that time, and he was in the audience for both talks. In the next session he gave a talk entitled “In which direction is the door?”, which likewise did not touch on the sensitive question of his collaboration with Tsung-Dao Lee; in it he quoted what the physicist R. Dalitz, who had died shortly before, said at a conference on the history of physics in Paris in 1982 about having missed the idea of parity nonconservation. The article explains the title: early in 1957, on learning that Chien-Shiung Wu’s experiment had given a definite result, he had sent a telegram with the news to J. Robert Oppenheimer, then on vacation in the Virgin Islands, whose reply was only a few words telling him to walk out of the door; in a talk of 1956 he had likened the situation of physicists facing the parity question to that of a man in a dark room who knows there must be a door in some direction but does not know which.⁠[36]

In 1971, against the background of ping-pong diplomacy, he proposed a visit to China in a letter to his father, and Premier Zhou Enlai approved it; on July 20 he arrived in Shanghai on an Air France flight, 26 years after he had left China.⁠[1]

His father was then a patient at Huashan Hospital in Shanghai. Zhou Enlai hosted him at the Great Hall of the People in Beijing; he met Deng Jia-xian, a key contributor to China’s atomic and hydrogen bombs, and visited Hefei.⁠[1][2]

The trip was launched from Stony Brook. After returning to the United States he gave talks on what he had seen in China; Zhou Pei-yuan later praised him for building academic exchange between the United States and China. The chronology he amended records that he was questioned by the Federal Bureau of InvestigationFederal Bureau of InvestigationThe Federal Bureau of Investigation (FBI) is the federal investigative agency of the U.S. Department of Justice. It grew out of a force of special agents organized by Attorney General Charles J. Bonaparte in 1908, has used its present name since 1935 and is headquartered in Washington, D.C.Open the full entry (FBI) after he returned to the United States.⁠[7][1]

Tsinghua University’s obituary states that his 1971 visit led to a wave of visits to China by overseas scholars.⁠[21]

On his second visit to China, in 1972, he urged Zhou Enlai to emphasize basic science; Zhou Enlai agreed and directed Zhou Pei-yuan to act on it. On October 6 of that year Zhou Pei-yuan published a long article in Guangming Daily.⁠[1][2]

His father died in Shanghai on May 12, 1973, at the age of 77; at the memorial he spoke of his father’s contributions to mathematics education and his patriotism. In July of that year, on his fourth visit to China, he was received by Mao Zedong at Zhongnanhai.⁠[1]

James Simons came to Stony Brook University in 1968 to head the mathematics department, and from him he learned the concepts of fiber bundles. In 1975 he and Tai Tsun Wu published “Concept of Nonintegrable Phase Factors and Global Formulation of Gauge Fields” in Physical Review D, with a dictionary relating the terminology of gauge theory to that of fiber bundles. CERN Courier’s obituary credits his work relating gauge theories to fiber bundles with helping to inspire a renaissance of fruitful interplay between physics and mathematics. The Simons Foundation’s obituary notes that the two did not at first work together on science: he recalled that James Simons approached him about starting an anti-war fund on the campus in opposition to the Vietnam War, and that Stony Brook University raised more money than any other university. The memorial notice of the C.N. Yang Institute for Theoretical Physics says that his conversations with James Simons strengthened the link between physics and mathematics and led to a lifelong friendship.⁠[33][1][19][15][7]

In 1977 he was elected the first president of the National Association of Chinese Americans, a post he held until 1980; the association aimed to promote the prompt normalization of diplomatic relations between the United States and China.⁠[1][8][2]

On January 30, 1979, he hosted a welcoming banquet for Deng Xiaoping in Washington and gave a speech entitled “The responsibility to help build a bridge of friendship.” The chronology he amended, summarizing the speech, says that he “further emphasized that there is only one China and all Chinese should work together towards a united China”; the account of his life issued by Tsinghua University says that in the speech he stated that the establishment of diplomatic relations between China and the United States was in the interest of both peoples, stressed that there is only one China in the world and called on Chinese living abroad to contribute to the cause of China’s unification.⁠[1][2]

In 1980 he founded the Committee on Educational Exchange with China (CEEC) at Stony Brook University, raising funds from donors in the United States and Hong Kong; over more than a decade about one hundred Chinese scholars visited Stony Brook with its support.⁠[1][2]

In the same year he attended a particle physics conference held by the Chinese Academy of Sciences in Conghua, Guangdong.⁠[1]

In 1980 he and Robert L. Mills were jointly awarded the Rumford Prize.⁠[6][32]

In 1982 he wrote to the leaders of the Chinese government on the directions that scientific research should take.⁠[1]

In 1983 he, Li Hua-zhong, Y.W. Chan and Sin Wai-kin established the Foundation of Zhongshan University Advanced Research Centre in Hong Kong, of which he was elected chairman, to support basic research at Zhongshan University; when the foundation was wound up in 2007 its assets, including RMB 11 million, HK$360,000 and a 4,000-square-meter research building with its equipment, were donated to the university.⁠[1]

In 1986 he helped establish the Theoretical Physics Division at the Chern Institute of Mathematics of Nankai University.⁠[6][2]

He became an honorary professor of The Chinese University of Hong Kong in 1982 and in 1986 accepted a special chair there as Distinguished Professor-at-Large.⁠[31][20][2]

In 1986 he visited Taiwan for the first time, for Ta-You Wu’s birthday, and attended the 17th meeting of the academicians of Academia Sinica.⁠[1]

In the same year he received the U.S. National Medal of Science.⁠[1][8]

From 1989 to 1994 he was the first president of the Association of Asia Pacific Physical Societies, and from 1996 to 2004 president of the Asia Pacific Center of Theoretical Physics.⁠[8][2]

In 1992 National Tsing Hua University in Hsinchu, Taiwan, held an international symposium for his 70th birthday, and on June 18 of that year he was elected a Foreign Member of the Royal Society.⁠[1][6]

In 1993 he and Shing-Tung Yau established the Institute of Mathematical Sciences at The Chinese University of Hong Kong, of which he became co-director; in the same year he received the Benjamin Franklin Medal of the American Philosophical Society.⁠[31][6]

In 1994 he helped Mr. and Mrs. C.M. Cha establish the Qiu Shi Science and Technologies Foundation in Hong Kong and helped Ho Sin-hang, Leung Kau-kui, Ho Tim and Lee Quo-wei establish the Ho Leung Ho Lee Foundation; in the same year he was elected a foreign member of the Chinese Academy of Sciences and of the Russian Academy of Sciences.⁠[1]

The account of his life issued by Tsinghua University dates his help in setting up the two foundations to 1992.⁠[2]

The 1994 Bower Award and Prize in Science of the Franklin Institute in Philadelphia, worth $250,000, went to him for his part in formulating Yang–Mills theory; he was the first physicist to receive the award in its five years of existence.⁠[37]

He received the Albert Einstein Medal in 1995 and the N. Bogoliubov Prize in 1996.⁠[32]

In June 1997 Tsinghua University established its Center for Advanced Study, modeled on the Institute for Advanced Study in Princeton, with Hwa-Tung Nieh as director and with him as honorary director responsible for fund-raising; the center was renamed the Institute for Advanced Study in April 2009.⁠[38][1][2]

He set up foundations for the purpose, aiming to raise at least US$15 million; the institute’s own introduction dates his initiation of its foundation to 1998. An article of 2025 in The Paper, drawing on Tsinghua University’s account of his ties with the university, relates that on a visit on January 29, 1997, he called this the last thing in his life worth doing and said that he hoped, over a period of time, to help the university attract ten to twenty of the most promising young people.⁠[1][38][39]

Gu Binglin, director of the Institute for Advanced Study at Tsinghua University, recalls that between June 1996 and August 1997 he came to the university many times to advise on staffing, funding and planning for the new center. The article in The Paper quotes Gu Binglin, interviewed by the Beijing Evening News in 2012, as saying that he donated all of his Tsinghua University salary to recruit talent and train students, and that he recommended Andrew C. C. Yao to teach at the university.⁠[11][39]

In 1997 he attended the Hong Kong handover ceremony and received an honorary Doctor of Science degree from The Chinese University of Hong Kong. In the same year he underwent coronary bypass surgery in the United States, which the chronology describes as successful; Stephen L. Adler’s retrospective relates that he had a “mild heart attack” in 1997 while at Stony Brook and decided on quadruple bypass surgery.⁠[1][32][12]

Between 1997 and 2005 he wrote repeatedly to China’s leaders urging the country to develop free-electron lasers.⁠[2]

In 1999 he retired from Stony Brook University and became Albert Einstein Professor of Physics Emeritus. On May 21–22 the university held a retirement symposium for him and awarded him an honorary degree, and the Institute for Theoretical Physics was renamed the C.N. Yang Institute for Theoretical Physics. An article by Chiang Tsai-chien published in the China Reading Weekly (Zhonghua Dushu Bao) in 2007 says that at the retirement dinner held for him at Stony Brook in 1999 he reworked a line by the Tang poet Li Shangyin into one saying that as long as the sunset is infinitely beautiful there is no need to be melancholy at the approach of dusk.⁠[1][8][7][36]

In the same year he received the Lars Onsager Prize of the American Physical Society and became a professor at Tsinghua University. The American Institute of Physics’ record dates the start of his Tsinghua professorship to 1998. Physics World’s obituary gives the year of the Lars Onsager Prize as 1990.⁠[8][21][22]

In 1999 he decided to donate his papers, letters, manuscripts and medals, including the Nobel Prize medal, to The Chinese University of Hong Kong, which established the C.N. Yang Archive to hold them; the archive opened in September 2002, and its website, on a page dated August 2013, puts the collection at over 22,000 items.⁠[1][20]

In 2001 he was awarded the King Faisal International Prize.⁠[1]

In 2002 Tsinghua University held an International Symposium on Frontiers of Science for his 80th birthday; in the same year he helped establish the Shaw Prize and became chairman of its Board of Adjudicators, and the first Shaw Prizes were presented in September 2004.⁠[1][2]

In 2003 he moved back to the Tsinghua campus and wrote a poem on returning to his roots; thereafter he divided his time between Beijing and Hong Kong. Stephen L. Adler’s retrospective places the move in December. CERN Courier’s obituary notes that he returned to the Tsinghua campus of his childhood as a widower. An article by Chiang Tsai-chien published in the China Reading Weekly in 2007 says that Tu Chih-li had long been ill and that the couple had lived in the United States for her treatment and the family’s care; at the end of December 2003 he moved alone into a residence that had stood empty for more than a year, and for a year lived there on his own, looking after himself. The People’s Daily article quotes him as saying that his life had made a great circle: he grew up on the Tsinghua campus and, more than sixty years later, returned to his old home. Physics World’s obituary, by contrast, says that he returned to Beijing in 1997, when he became honorary director of the Center for Advanced Study at Tsinghua University.⁠[1][32][12][15][36][11][22]

On September 13, 2004, he began teaching general physics to first-year undergraduates at Tsinghua University, lecturing twice a week for a semester; the course had been suggested by Zhu Bangfen, then chair of the physics department. The People’s Daily article gives his age that day as 82; by either recorded date of birth he was 81.⁠[11]

At his invitation and under his influence, scientists including Chia-Chiao Lin, Andrew C. C. Yao and Wang Xiaoyun joined the Institute for Advanced Study at Tsinghua University; Andrew C. C. Yao became a full-time member of its faculty in 2004.⁠[11][38]

His collection Shu Guang Ji was published in 2008. An excerpt from Chiang Tsai-chien’s biography of him, printed in the Beijing Evening News in 2011, says that the collection was published by SDX Joint Publishing in Beijing in January 2008 and that in the book he wrote that the Chinese nation had at last come through the long night and seen the dawn, that at 85 he would not see full daylight, and that Weng Fan had promised to see it for him.⁠[1][40]

In 2010 he solved one-dimensional many-component Bose problems and published the results in Chinese Physics Letters; in the same year he was elected an honorary member of the Japanese Academy of Sciences. The same excerpt relates that he returned to Beijing from Britain in September 2010 and on September 13 was suddenly taken ill with severe vomiting and a high fever; for several hours he was semi-conscious and even felt as though his mind had separated from his body, and although his mind remained clear, others could not understand what he said; Weng Fan was badly frightened. After a week in Peking Union Medical College Hospital (Xiehe Hospital) he left fully recovered, his doctors attributing the infection to the acid-suppressing medicine he had taken for many years, which had weakened his body’s defenses against germs. At the end of October he moved to his residence in Hong Kong, intending to stay for some time. The University of Chicago’s obituary notes that in the autumn of 2010 he attended the opening events of the university’s Center in Beijing and its first academic conferences.⁠[1][40][9]

In 2010 he published an article on a biography of Tsung-Dao Lee and on the controversy over the discovery of parity nonconservation, which appeared in the newspaper Zhonghua Dushu Bao (March 17) and in Twenty-First Century (April 2010).⁠[1]

In 2012 Tsinghua University celebrated his 90th birthday and presented him with a black crystal engraved with thirteen of his major contributions, and The Chinese University of Hong Kong held a series of celebrations in September. In December of that year he published “Weighing in on Wu’s Legacy” in Physics World, about Chien-Shiung Wu’s parity nonconservation experiment of 1956–1957.⁠[1][19]

On April 1, 2015, he renounced his United States citizenship. In the remarks published by Xinhuanet in 2017 he said that this, too, was not a simple decision; that the United States is a beautiful country which gave him very good opportunities for scientific research, that he was grateful to it, and that he knew many American friends would not approve of his giving up American citizenship. He quoted his close friend Xiong Bingming as saying that, although his father was gone, his father’s blood still circulated in his body, and added that what circulated in his body was his father’s blood, the blood of Chinese culture. In the remarks he gave his age as 94.⁠[30][1]

At the end of 2016, having given up foreign citizenship and become a Chinese citizen, he applied to change from foreign member to member of the Chinese Academy of Sciences. In February 2017 information from the Bureau of Academic Divisions of the Chinese Academy of Sciences showed that he had formally become a member under the academy’s charter and its interim measures on the conversion of foreign members, and that he had joined the Division of Mathematics and Physics; it was the first such conversion in the history of the academic divisions, and Andrew C. C. Yao became a member at the same time. Pages differ in how they state his nationality: a curriculum vitae on Tsinghua University’s website, marked as revised on December 15, 2000, prints “Citizenship: United States”; the Royal Society’s record, last modified on October 29, 2025, enters both “Chinese” and “American” under nationality; Physics World’s obituary says that he “obtained US citizenship, but renounced it in 2015”; and the Encyclopaedia BritannicaEncyclopædia BritannicaEncyclopædia Britannica is a general English-language encyclopedia first published in Edinburgh, Scotland, in 1768; the name also refers to its publisher, Chicago-based Encyclopædia Britannica, Inc. (which presents itself as The Britannica Group). The print edition ended in 2012, and the company’s main businesses since then have been the online encyclopedia Britannica.com, digital education products for schools and libraries, and Merriam-Webster dictionaries.Open the full entry article calls him a “Chinese-born American theoretical physicist” and states: “He became a U.S. citizen in 1964.”⁠[30][1][5][6][22][41]

On September 4, 2016, the WeChat account “Intellectuals” published his article “China Should Not Build A Super Collider Today,” which set off a series of discussions.⁠[1]

Physics World’s obituary states that he opposed building the Circular Electron Positron Collider in China, calling it “inappropriate” for a developing country and describing the timing in 2016 as “really bad.”⁠[22]

In 2018 his collection Chen Xi Ji and an updated and expanded tenth-anniversary edition of Shu Guang Ji were published, and he became a co-initiator of the Science Exploration Award.⁠[1][2]

In 2019 he received the Qiu Shi Lifetime Achievement Award, and in 2020 he was appointed honorary dean of the Stony Brook Institute at Anhui University.⁠[1][42]

In May 2021 he donated more than 2,000 books, manuscripts, audio-visual materials and works of art to Tsinghua University, which set up the C N Yang Archive at Tsinghua University to hold them.⁠[2][1]

On September 22, 2021, Tsinghua University, The Chinese University of Hong Kong and the Chinese Physical Society jointly held a conference celebrating his hundredth year, at which he gave a speech and said that the two things he had cared about most in his life were the development of China and the development of physics.⁠[1][2][11]

He died of illness in Beijing at 12:00 noon on October 18, 2025, at the age of 103.⁠[2][21]

At his death he was a member of the Chinese Academy of Sciences, a professor at Tsinghua University and honorary director of its Institute for Advanced Study, as well as Distinguished Professor-at-Large and director of the Institute of Theoretical Physics at The Chinese University of Hong Kong.⁠[21][32]

Tsinghua University issued an account of his life the same day. Stony Brook University’s president, Andrea Goldsmith, wrote in a message of October 19 that the university would recognize his legacy in the coming months, and Dennis Lo Yuk-ming, vice-chancellor and president of The Chinese University of Hong Kong, called him a “scientific giant” in that university’s tribute. Physics World’s obituary quotes Andrea Goldsmith: “The world has lost one of the most influential physicists of the modern era.”⁠[2][34][32][22]

On the morning of October 24, 2025, the farewell ceremony for him was held at Babaoshan Revolutionary Cemetery in Beijing. The CCTV News account carried by Tsinghua University says that faculty, students and alumni of Tsinghua University and people from all walks of life went to the cemetery of their own accord to see him off; the Jimu News article says that people from many walks of life, among them the Chinese Academy of Sciences and graduates of Tsinghua University, went to Babaoshan to see him off.⁠[43][44]

He was the first of five children: his brothers Chen Ping Yang, Zhen-han and Zhen-fu were born in 1930, 1932 and 1937, and his sister Chen-yu in 1934. Chen Ping Yang was a professor at Ohio State UniversityOhio State UniversityOhio State University (officially The Ohio State University) is a university in Columbus, Ohio, United States, established by the state legislature in 1870.Open the full entry. The chronology records that in 1985 he moved his mother to Hong Kong and that his brother Zhen-fu died on October 2 of that year; that his mother, Luo Meng-hua, died at the age of 91 at the Prince of Wales Hospital in Hong Kong on September 12, 1987; and that the ashes of his parents and of Zhen-fu were later entombed at the Dongshan cemetery in Suzhou. Stephen L. Adler’s retrospective quotes him describing his mother as “a woman of great will power and self-discipline” who toiled from dawn to night, year after year, during the war.⁠[4][1][12]

While teaching mathematics at a high school in China he had met Tu Chih-li, then a student there and the daughter of the Kuomintang general Tu Yu-ming; the two met in Princeton in 1949 and were married there on August 26, 1950. Stephen L. Adler’s retrospective adds that she had been in a class he taught at a high school in Kunming, though he did not know her well then, and that the two met again over dinner at the Tea Garden, the only Chinese restaurant in Princeton; it spells her father’s name Du Yuming and calls him a Nationalist general who was captured by Mao’s army and served ten years in prison; the Oriental Outlook article calls her the eldest daughter of the senior Nationalist general Tu Yu-ming. CERN Courier’s obituary says that he wrote that he would probably have taken Enrico Fermi’s advice and returned to the University of Chicago but stayed in Princeton to be nearer to her; it gives the year of the marriage as 1951, while the Royal Society’s record gives 1950.⁠[5][1][12][15][6][17]

They had three children: Franklin (born 1951), Gilbert (born 1958) and Eulee (born 1961). The chronology records that his eldest son’s Chinese name, Guangnuo, was given by his grandfather. The 2007 article by Chiang Tsai-chien in the China Reading Weekly says that the two sons and the daughter were all born and raised in the United States; the daughter is a physician, and in 2006 he and Weng Fan visited her in MontanaMontanaMontana is a state in the northwestern United States, with the Rocky Mountains in the west and the Great Plains in the east; its capital is Helena and its largest city is Billings. Montana became the 41st U.S. state on November 8, 1889, and the 2020 census (April 1, 2020) counted 1,084,225 residents.Open the full entry and stayed for a while at her home; the two sons had met Weng Fan in Beijing and Hong Kong, and his younger siblings in the United States had also gone to Beijing to meet her.⁠[4][1][36]

Tu Chih-li died in the United States on October 19, 2003. On December 24, 2004, he married Weng Fan. The chronology says that Tu Chih-li died after a long illness. The Royal Society’s record dates his marriage to Weng Fan to 2005. The chronology records that in 1995, when he and Tu Chih-li visited Shantou University, the university appointed a first-year student, Weng Fan, as their guide; an excerpt from Chiang Tsai-chien’s biography, printed in the Beijing Evening News in 2011, quotes him as saying that he and Tu Chih-li met her in the summer of 1995 when they attended an international conference of physicists at Shantou University, and that she wrote them a short letter in February 2004. By the same excerpt, he wrote in an e-mail to a small circle of relatives and friends that the two had become engaged on November 5, 2004, and later confirmed to the author that the engagement had been made by telephone; he also said that he afterwards let his children in the United States and his younger siblings know about Weng Fan and the engagement, and that they all gave him their blessing; after the news appeared in the author’s journal Zhishi Tongxun Pinglun and caused a sensation, he and Weng Fan promptly registered their marriage and went to Hainan Island for their honeymoon; he said publicly that had he not married Weng Fan he might have married another woman. The 2007 article by Chiang Tsai-chien in the China Reading Weekly says that he knew that the 54-year difference in their ages would inevitably cause talk but was prepared for it, and that he said people would one day know that theirs was a romantic love story; at the end of March 2006 he took Weng Fan to the United States for the first time, and in that period she also accompanied him when he went to conferences in Japan and Europe. The excerpt printed in the Beijing Evening News relates that when he and Weng Fan returned from the United States to Hong Kong in June 2006 and again drew the attention of the press, they were asked about rumors that they were expecting a child; he later said privately that they had considered it but had decided that it was not advisable for them to have children. The 2007 article in the China Reading Weekly adds that at the beginning of July 2006 he went with Weng Fan to Taipei for the meeting of academicians of Academia Sinica, which set off a wave of press coverage in which the question was raised again. Stephen L. Adler’s retrospective says that Weng Fan was 52 years his junior and was his constant companion for the final two decades of his life.⁠[1][6][40][36][12]

He chaired the Division of Particles and Fields of the American Physical Society (1970–1971), the Division of Particles and Fields of the International Union of Pure and Applied Physics (1972–1976) and the Scientific Advisory Board of the Max Planck Institute for Physics (1980–1983).⁠[8][5]

He was a trustee of the Woods Hole Oceanographic Institution (1962–1978), Rockefeller UniversityThe Rockefeller UniversityThe Rockefeller University is a biomedical research university on Manhattan’s Upper East Side in New York City, devoted mainly to scientific research and graduate education; it grew out of the Rockefeller Institute for Medical Research founded by John D. Rockefeller.Open the full entry (1970–1976), the Salk Institute for Biological Studies (1978–1989), the Stony Brook Foundation (1981–1999) and Brookhaven Science Associates (1998–1999), and a director of the Neuroscience Institute (1983–1988) and of Scientific American, Inc. (1983–1990).⁠[8]

He was also a member of the Science Advisory Committee of International Business MachinesIBMIBM (International Business Machines Corporation) is an American information technology company, renamed in 1924 from the Computing-Tabulating-Recording Company (C-T-R).Open the full entry (IBM) (1966–1971), of the High Energy Physics Advisory Panel of the United States Atomic Energy Commission (1968–1970) and of the board of the American Association for the Advancement of Science (1975–1979).⁠[8][5]

The lectureships he held include the Loeb Lectures at Harvard UniversityHarvard UniversityHarvard University is a private research university in Massachusetts, established by the Massachusetts Bay Colony legislature in 1636 and named in 1639 for early benefactor John Harvard. Its principal campuses are in Cambridge and the Allston and Longwood neighborhoods of Boston. It includes Harvard College, graduate and professional schools, and the Radcliffe Institute for Advanced Study. Two governing boards share oversight. Alan M. Garber was president as of October 2026, and the endowment stood at $56.9 billion at the end of fiscal 2025.Open the full entry (1957, 1972 and 1997), the Gibbs Lecture of the American Mathematical Society, the Vanuxem Lectures at Princeton University and the Pauli Lectures at ETH Zurich, and he was Lorentz Professor at Leiden; in 1988 he was the first laureate of the Oskar Klein Memorial Lecture and Medal.⁠[5][6]

In February 2011 he gave an interview about his life and career for the Simons Foundation’s Science Lives project.⁠[33]

He was also a member of the American Philosophical Society, of Academia Sinica, of the Brazilian, Venezuelan, Polish, Royal Spanish and Korean academies and of the Pontifical Academy of Sciences; the biography written at the time of the award and published on the Nobel Prize website records that he had by then been elected a fellow of the American Physical Society and of Academia Sinica.⁠[5][4]

Tsinghua University’s obituary states that he was a member or foreign member of more than ten national and regional academies of sciences and received honorary doctorates from more than twenty universities.⁠[21]

His other awards include the Enrico Fermi Medal (1979), the Oppenheimer Memorial Plaque (1981), the Moscow State University Medal (1992), the China International Science and Technology Cooperation Award (1995), the Academicum Pontificium (2000) and the Marcel Grossmann Award (2015). The Royal Society’s record gives the citation of the Marcel Grossmann Award, “for deepening Einstein’s geometrical approach to physics in the best tradition of Paul DiracPaul DiracPaul Dirac (1902–1984) was a British physicist and one of the founders of quantum mechanics and quantum electrodynamics. He formulated the relativistic Dirac equation for the electron and predicted antiparticles, was Lucasian Professor of Mathematics at Cambridge from 1932 to 1969, and shared the 1933 Nobel Prize in Physics with Erwin Schrödinger.Open the full entry and Hermann Weyl,” and lists him in the Asian Scientist 100 of 2016 and 2020.⁠[31][42][6]

Other institutions that awarded him honorary degrees were Brooklyn Polytechnic Institute (1965), the University of Wroclaw (1974), Gustavus Adolphus College (1975), the University of MarylandUniversity of Maryland, College ParkThe University of Maryland, College Park is a university in College Park, Maryland, United States, whose forerunner was the Maryland Agricultural College.Open the full entry (1979), the University of DurhamDurham UniversityDurham University, legally named the University of Durham, is a research university in Durham, North East England, and a member of the Russell Group. Founded under an 1832 Act of Parliament and granted a Royal Charter in 1837, it describes itself as England’s third oldest university and has a collegiate system in which all students belong to one of 17 colleges. Its current Vice-Chancellor and Warden is Karen O’Brien and its Chancellor is Fiona Hill; it had 21,588 students in 2023/24.Open the full entry (1979), Fudan University (1984), ETH Zurich (1987), Moscow State University (1992), Drexel University (1995), Tsing Hua University and Chiao Tung University in Taiwan (both 1996), the University of MichiganUniversity of MichiganThe University of Michigan is a university founded in Detroit in 1817 that moved to Ann Arbor, Michigan, in 1837; it is governed by a statewide-elected Board of Regents and also has campuses in Dearborn and Flint.Open the full entry (1998), Washington College (1999), Hong Kong Baptist University (1999) and Chung-Cheng University in Taiwan (2000).⁠[5]

His book Elementary Particles: A Short History of Some Discoveries in Atomic Physics was published by Princeton University Press in 1962.⁠[19]

His Selected Papers 1945–1980 With Commentary was published in the United States by Freeman and Company in May 1983 and reprinted by The Commercial Press in 2020; a sequel, Selected Papers II With Commentaries, was published by World Scientific in 2013.⁠[1][19]

His Chinese-language collections include Forty Years as a Student and a Teacher (Joint Publishing, 1985), Again Ten Years (China Times Publishing, 1995) and the two-volume Collected Papers of Chen Ning Yang (edited by Zhang Dian-zhou, East China Normal University Press, 1998).⁠[1]

In 2002 Chiang Tsai-chien’s Biography of Yang Chen-ning was published in Taiwan.⁠[1]

In 1997 asteroid 3421, discovered by the Purple Mountain Observatory of the Chinese Academy of Sciences, was named after him.⁠[2]

The Institute for Advanced Study at Tsinghua University has C.N. Yang Professorships, endowed by a donation from Mr. and Mrs. Dunson Cheng, and a C.N. Yang Fellowship for first-year graduate students.⁠[38]

World Scientific has published several volumes connected with him, among them the proceedings of his retirement symposium, Symmetry & Modern Physics (2003), 50 Years of Yang-Mills Theory, edited by Gerardus ’t Hooft (2005), and a Festschrift for his centenary (2022).⁠[1][7]

Tsinghua University’s obituary calls him “one of the greatest physicists of the 20th century.”⁠[21][9]

An article in The Scientist in 1995 judged that physicists widely regard Yang–Mills theory as being as fundamental as Albert EinsteinAlbert EinsteinAlbert Einstein (1879–1955) was a German-born physicist who formulated the special theory of relativity in 1905 and the general theory in 1915 and received the 1921 Nobel Prize in Physics for his discovery of the law of the photoelectric effect. From 1933 until his death he was a professor at the Institute for Advanced Study in Princeton, New Jersey, United States.Open the full entry’s theory of relativity; CERN Courier’s obituary ranks non-Abelian gauge theories with Maxwell’s equations and general relativity as foundations of modern physics.⁠[37][15]

Ka Yee C. Lee, interim dean of the Physical Sciences Division at the University of Chicago, judged that his work “laid the groundwork for the Standard Model of particle physics.”⁠[9]

George Sterman, director of the C.N. Yang Institute for Theoretical Physics, wrote at the time of the 1999 retirement symposium that his discoveries and methods continue to enable discoveries by others.⁠[7]

In an interview with Radio Television Hong Kong (RTHK) on January 28, 1995, he said that his greatest contribution had been to help Chinese people overcome a widespread sense of inferiority.⁠[1][11]

The biography written at the time of the award and published on the Nobel Prize website describes him as “a quiet, modest, and affable physicist.” The biography on Tsinghua University’s website also says: “He is a hard worker allowing himself very little leisure time.” The account of his life issued by Tsinghua University says that preferring the plain to the clever and simplicity to ornament was his attitude both to scholarship and to life. Stephen L. Adler’s retrospective quotes him writing of the “tendency toward restraint” that he and his collaborator Wu shared in their research, says that he was “not incapable of the occasional sharp remark,” and quotes his own summary of his life, which ends with the words “Traversed in deep gratitude.”⁠[4][5][2][12]

Institute for Advanced Study: Official website: https://www.ias.edu/ (opens in a new window).⁠[45]

Stony Brook University: Official website: https://www.stonybrook.edu/ (opens in a new window).⁠[46]

Tsinghua University: Official website: https://www.tsinghua.edu.cn/en/index.htm (opens in a new window).⁠[47]

Institute for Advanced Study, Tsinghua University: Official website: https://www.ias.tsinghua.edu.cn/en/index.htm (opens in a new window).⁠[48]

C.N. Yang Archive, The Chinese University of Hong Kong: Official website: https://cnyangarchive.cuhk.edu.hk/?lang=en-us (opens in a new window).⁠[20]

University of Chicago: Official website: https://www.uchicago.edu/ (opens in a new window).⁠[49]

The Chinese University of Hong Kong: Official website: https://www.cuhk.edu.hk/english/index.html (opens in a new window).⁠[50]

National Academy of Sciences: Official website: https://www.nasonline.org/ (opens in a new window).⁠[51]

Chinese Academy of Sciences: Official website: https://www.cas.cn/ (opens in a new window).⁠[52]