Yang is being honored for his work in forming the Yang-Mills theory, which is widely held by physicists to be as basic a contribution to science as Albert Einstein's theory of relativity. The theory is considered to be the foundation for current understanding of how subatomic particles interact, a contribution which has restructured modern physics and mathematics.
The award will be given to Yang on May 4 at the Franklin Institute Medal Awards Program. Yang, the first physicist to be honored with the five-year-old award, will receive a gold medal in addition to the cash prize. The size of the award makes it the "richest American prize in science," according to an institute statement. The prize, along with 16 other honors to be presented at the ceremony, is selected by the institute's Committee on Science and the Arts and is administered by the Benjamin Franklin National Memorial.
Yang, Albert Einstein Professor and director of the Institute for Theoretical Physics at the State University of New York (SUNY) at Stony Brook, developed the theory with Robert Mills, a professor of physics at Ohio State University, while they were visiting scientists at Brookhaven National Laboratory in Upton, N.Y.
"I think it was '53 or early '54 and I shared an office with [Yang] and Mills while they were working out the Yang-Mills theory," recalls Burton Richter, immediate past president of the American Physical Society and director of the Stanford Linear Accelerator Center at Stanford University. "I remember the blackboards full of equations sprawling all over the office and my pitiful attempts to understand what they were doing.
"I think it's wonderful work. [Yang] has been one of the great contributors to high-energy physics throughout his career. I think the whole physics community will be happy, in particular, that the Yang-Mills theory work is being honored."
"I am, of course, pleased that my work is being recognized," says the 72-year-old Yang. "I'm especially pleased that Professor t'Hooft is at the same time receiving an award from the Franklin Institute for his contributions [to particle physics]," he notes, referring to physicist Gerard t'Hooft of the Institute for Theoretical Physics at Utrecht University in the Netherlands, who has won the institute's Franklin Medal, cited for his "pivotal role in laying the foundation for the unified field theory of the fundamental forces of nature."
Yang came to the United States from China in 1946 on a Boxer Fellowship to study at the University of Chicago, where he had hoped to work on his Ph.D. with Enrico Fermi at Argonne National Laboratory. But foreign nationals were barred by the federal government from training with Fermi, who played a pivotal role in the development of the atomic bomb.
Instead he received his Ph.D. in physics under Edward Teller at Chicago in 1948. From there he moved to a postdoctoral position with J. Robert Oppenheimer at the Princeton, N.J.-based Institute for Advanced Study in 1949, and remained there until assuming the newly created Einstein professorship at SUNY in 1966.
In 1957, he received, along with colleague Tsung-Dao Lee from Columbia University, the Nobel Prize in physics for disproving the law of conservation of parity, a long-held theory about symmetry in elementary physics (T.D. Lee and C.N. Yang, "Question of parity conservation in weak interactions," Physical Review, 104:254, 1956).
Yang, a member of the National Academy of Sciences, also received the National Medal of Science in 1986 among numerous other awards.
The Yang-Mills theory explains the interaction of four forces in nature--weak and strong interactions, gravity, and electromagnetism--that control how subatomic particles behave and provides the fundamental principles for modern particle physics.
"The earliest understanding of these forces was Newton's understanding of gravity," Yang explains. "The next to be understood were Maxwell's equations for electric and magnetic forces. What the gauge [Yang-Mills] theory [covers] is the equations that govern the other two types of forces. And furthermore, it turns out that once you understand those, Maxwell's and Newton's forces also fall into the same category.
"So now we realize that all fundamental forces are forces that obey gauge equations, which are the ones that Mills and I wrote down in 1954."
The theory was set down in a journal article: C.N. Yang, R.L. Mills, "Conservation of isotopic spin and isotopic gauge invariance," Phys. Rev. 96:191, 1954. The paper has been cited more than 1,200 times to date, according to the Philadelphia-based Institute for Scientific Information (see chart below).
Indeed, many in the physics community consider the Yang-Mills theory to be of greater significance than overturning the parity theory, for which he won the Nobel.
"The Yang-Mills theory--for which I nominated him--is the theory that underlies the behavior of all matter and this is commonly accepted; however, he's never received a major prize for it," stresses Gerald Brown, SUNY Distinguished Professor of Physics at Stony Brook's Institute for Theoretical Physics. "He did receive [the Nobel] with Tsung-Dao Lee for parity violation, but the Yang-Mills theory is a much more important discovery, certainly the most important in the second half of our century, after relativity and quantum mechanics."
Larry Tise, executive director of the Benjamin Franklin National Memorial, relates that the Bower selection committee concurred with Brown: "[The committee] came to the conclusion that the work that Yang did for the Nobel Prize, compared to the work on the Yang-Mills theory, is totally different--with totally different consequences, and that this work actually has had a much more profound effect throughout the whole realm of physics and mathematics. It has gone unrecognized as one of the greatest achievements in physics in the 20th century."
Brown also notes that three experimental physicists, Massachusetts Institute of Technology researchers Henry Kendall and Jerome Friedman and Richard Taylor of Stanford University, received the 1990 Nobel Prize in physics for applications of the Yang-Mills theory. "Their experiments were only possible if they had known the theory," Brown asserts. "If there was any doubt that the [Yang-Mills] theory was valid, that  Nobel Prize certainly verified that the [Nobel] committee thought that the theory held."
Physicists say it is this universal applicability that is unique to Yang's work. "What is most impressive about Yang is that he is able to generalize successfully, which is a very rare ability," says Maurice Goldhaber, Distinguished Scientist, emeritus, at Brookhaven and its former director from 1961 to 1973. Goldhaber, who has known Yang for more than 40 years, worked at Brookhaven when Yang and Mills conceived the Yang-Mills theory. "This showed in the generalization which led to the overthrow of parity, and it shows again in the generalization of the gauge theory from electromagnetism to particle physics."
"[His body of work] is absolutely central to our understanding of the physical world today," remarks Frank Wilczek, a professor of natural sciences at the Institute for Advanced Study. "He's perhaps one of the most, if not the most, eminent theoretical physicists alive today. His work is an amazing combination of mathematical power and elegance. I think what's most impressive about it is that he's been able to find ideas that are both beautiful and true."
In addition to his scientific achievements, Yang is being honored for his humanitarian efforts. The award citation emphasizes his "championing of understanding between China and the Western world and his promotion of science education among the youth from all corners of the globe."
With the opening of relations between the U.S. and China, Yang returned to China for the first time in 1971. "The climate was changing and I decided to go back and visit my parents," Yang remembers. "After I came back I thought that, as a person deeply involved in both China and the U.S. and who understands the cultures of both countries very well, it was my responsibility to promote understanding between the two.
"I thought that Chinese science should be promoted because that would contribute to the well-being of the people in China and also to the peace and stability of the whole world. So that became my goal for the next 20 or so years."
One of his many efforts includes establishing a visiting scientist program at the SUNY-Stony Brook institute, where more than 100 Chinese researchers have come for one-year stays since the early 1980s.
The Bower awards were established with a $7.5 million endowment from Henry Bower, a Philadelphia chemical manufacturer.