EC George Sudarshan: The titan of 20th century physics
Professor E.C.George Sudarshan was perhaps the most wellknown physicist India has produced in the second half of the twentieth century. He is a product of India’s own science
teaching establishment. His formative years were completely spent in India. Born in Kottayam, and studied in Kottayam, Chennai, and Mumbai, this great son of India achieved unmatched levels of intellectual and scientific creativity. ECG Sudarshan made significant contributions to several areas of physics, including elementary particle physics, quantum optics, quantum information, quantum field theory, gauge field theories, classical mechanics and foundations of physics.
He wrote more than 500 scientific papers as well as 10 books on a variety of topics like Classical Dynamics, Quantum Optics, and Philosophy. A lover of education, learning, and teaching, he worked at the University of Rochester, Harvard, Syracuse, the Indian Institute of Science Banglore, the Institute of Mathematical Sciences Chennai, and the University of Texas where he was a professor for 47 long years.
Sudarshan was the originator (with Robert Marshak) of the V-A theory of the weak force , which eventually paved the way for the unification of the weak and electromagnetic interactions by Steven Weinberg, Abdus Salam and Sheldon Glashow, which in turn led to the 1979 Nobel Prize in Physics for them. He developed a quantum representation of coherent light, later known as Sudarshan–Glauber representation. Concurrently with with Roy Glauber, Sudarshan developed a quantum mechanical description of light that would become the foundation of a new field: quantum optics. Glauber went on to share the 2005 Nobel Prize in Physics for that work.
Quantum optics is an area where Sudarshan made very significant contributions.His theorem proves the equivalence of classical wave optics to quantum optics. The theorem makes use of the Sudarshan representation. This representation also predicts optical effects that are purely quantum, and cannot be explained classically. He also developed a formalism called dynamical maps that is one of the most fundamental formalisms to study the theory of open quantum systems. He, in collaboration with Baidyanath Misra, also proposed the quantum Zeno effect.
Early Life
Ennackal Chandy George (ECG) was born into a Syrian Orthodox Christian family on 16 September 1931 in Pallam, near Kottayam town in Kerala. His mother Achamma was a school
teacher, and father E. I. Chandy was a revenue inspector. After high school, he completed the twoyear Intermediate at the Church Mission Society (CMS) College in Kottayam in 1948. From CMS College, ECG went to the Madras Christian College (MCC) in Chennai for his B Sc (Honours) in Physics(1948 to 1951), after which he stayed on for a year as a demonstrator in physics. In 1952, he received the MA degree of the University of Madras. ECG then joined the Tata Institute of Fundamental Research (TIFR) in Mumbai as a research student.
Sudarshan and his graduate student V. K. Deshpande first proposed the existence of particles called tachyons that would violate Einstein's theory of relativity by travelling faster than the speed of light. They would also have the bizarre consequence of allowing signals to be received by an observer before it was actually sent, violating the principle of causality. So far, no experimental evidence has been found to support their existence. Tachyon is considered as a revolutionary idea within the framework of the Special Theory of Relativity
The years he spent at TIFR turned out to be very important for by ECG in many ways. Initially he was asked to do experimental work in particle physics. Later he turned to theoretical work, developing his true interests and strengths. ECG developed close contacts with many leading scientists of India, then doing research at TIFR.
Visits to TIFR by two great figures of theoretical physics became turning points in the life of ECG. In 1954, the legendary P. A. M.Dirac, visited TIFR and gave a course of lectures on quantum mechanics. The lecture notes were prepared by ECG and another research scholar K. K. Gupta. This work brought ECG and Dirac into close contact and ECG got a unique and fortunate opportunity to learn the subject from the master himself. ECG greatly valued Dirac’s friendship, and the two remained lifelong friends. Another important visitor to TIFR in this period,was the leading theoretical elementary particle physicis Robert Eugene Marshak. During his visit and lectures in August 1953, Marshak was so impressed by ECG that he persuaded him to come to Rochester and work with him for his PhD. ECG reached Rochester in September 1955. Some time before this, in 1954, ECG and Lalitha Rau, another student at TIFR, were married. It was at this time that he added the Hindu name ‘Sudarshan’ to his christian name George. He thus became E C George ‘Sudarshan’.
In the United States
ECG ‘Sudarshan’ reached Rochester at a time when there was great excitement in the field of elementary particle physics. Many new particles had been discovered in the cosmic radiation. But their decay modes and characteristics remained as intriguing puzzles. In 1956, T. D. Lee and C. N. Yang suggested that spatial inversion may not be a valid symmetry of nature in these processes . Parity may not be conserved in the weak interactions. After it was experimentally confirmed that parity was not conserved in weak processes, Lee and Yang were given the 1957 Nobel Prize in Physics.
The original theory of ß-decay was proposed by Enricho Fermi in 1933-34. Fermi had assumed conservation of parity. It became a major problem to determine the correct form of a universal Fermi interaction to replace Fermi’s original theory, capable of describing ß-decay as well as all strange particle decays, incorporating parity violation. Marshak asked George ‘Sudarshan’ to do his Ph D. work in this challenging and promising field. By early 1957, after an extensive study of all existing experimental results, Sudarshan and Marshak had arrived at the so-called ‘V – A’ structure for the universal Fermi interaction. This ultimately became the structure on which the edifice of unification of electromagnetic and weak nuclear interactions was built.
Sudarshan completed his Ph D in 1958, and then spent two years (1957 to 1959) as Research Fellow with Julian Schwinger at Harvard University. During this period he continued collaborations with Marshak and Okubo; the trio published many joint papers in these years. At Harvard he did a well-known piece of work with K. Johnson, a student of Schwinger, on inconsistencies in higher spin field theories in external fields. Some years later Sudarshan also collaborated with S. Deser and W. Gilbert on problems in axiomatic quantum field theory.
In 1959, ECG Sudarshan returned to Rochester and joined the physics faculty as Assistant Professor; two years later he became Associate Professor. His early students in these years came from different countries; R. Acharya from India; Thomas Jordan , Douglas Currie, Korkut Bardakci from Turkey; M. Y. Han from South Korea and M. E. Arons, Gabriel Pinski and N. Mukunda (also from India). It was in 1961 that his fundamental work with P.M. Mathews and J. Rau titled ‘Stochastic dynamics of quantum mechanical systems’ appeared, heralding the quantum theory of open systems which is today at the base of quantum information theory.
In 1963, Sudarshan discovered the Diagonal Coherent State Representation for arbitrary states of quantum optical fields. Another important work published in 1963 was with Currie and Jordan, leading up to the No Interaction Theorem for classical relativistic Hamiltonian theories of point particles. Sudarshan took sabbatical leave in 1963–64, spending the first half at the University of Bern, and the second at Brandeis University. At Bern he gave a set of lectures on quantum optics; the notes of which served as the basis for the 1968 book Fundamentals of Quantum Optics with J. R. Klauder. This is one of the early books on the subject. In 1964,
Sudarshan moved from Rochester to Syracuse University as Professor, and created a group in elementary particle physics. The best known result from Sudarshan’s group in Syracuse is the O’Raifeartaigh Theorem showing the impossibility of combining internal symmetry and relativistic invariance in a nontrivial manner.
In 1969, Sudarshan moved from Syracuse to the University of Texas at Austin, as Professor and Co-Director of the Centre for Particle Theory. He remained in Austin for the rest of his professional life in the US. Among the areas he explored in almost five decades, there were relativistic wave equations, indefinite metric quantum field theories using the concept of shadow states, the Zeno paradox and effect in quantum mechanics, quantum mechanics of open systems, the measurement problem in quantum mechanics, and supersymmetry in particle physics. In addition, there were long-term collaborations with colleagues in Italy and Spain, and in India.
Sudarshan had very cordial relationships with two outstanding Japanese theoretical physicists: Hiroomi Umezawa (1924–1995) and Yoichiro Nambu (1921–2015). Nambu worked at the University of Chicago and won the Nobel Prize in 2008. Sudarshan’s student Han collaborated with Nambu in the construction of the Han–Nambu quark model in 1965.
Though Sudarshan made USA his academic base, he always maintained strong links with the Indian science community. His first involvement was in 1970–71, when he was Sir C. V. Raman Distinguished Professor at the University of Madras.
His involvement with Indian science in a more substantive way began in 1971–72. Satish Dhawan was the Director of IISc Banglore from 1962 to 1981. He was India’s most distinguished fluid dynamicist and aeronautical engineer, who placed India’s space programme on secure and strong foundations. D. S. Kothari was at that time Chairman of the University Grants Commission of India. Earlier he had been Professor of Physics at Delhi University. As a result of initiatives taken by Dhawan and Kothari, George Sudarshan was invited to set up and direct a new Centre for Theoretical Studies (CTS) at IISc. This was to be concurrent with his responsibilities at the University of Texas at Austin, with him making two visits each year to IISc. The initial faculty put together in 1972–73 by Sudarshan with guidance from Dhawan consisted of Roddam Narasimha aeronautical engineering and fluid dynamics), K.P. Sinha ( theoretical physics), N.Mukunda (theoretical and mathematical physics), Madhav Gadgil (evolutionary biology and ecology), Sulochana Gadgil (atmospheric science and monsoon meteorology), and Hombegowda Sharat Chandra (human genetics). Under Sudarshan’s leadership the centre flourished and contributed to different fields of science.
in 1985, Sudarshan was invited to the Directorship of Institute of Mathematical Sciences (IMSc) in Chennai. He held this position till 1990, rejuvenating and expanding the scope of the Institute’s activities. With great vigour, Sudarshan was able to maintain and expand his research activities in the two continents. Sudarshan pursued somewhat separate streams of activity at USA, and in India. At Austin, the focus was largely on the Zeno problem in quantum mechanics, theory of open systems and their quantum dynamics, wave equations, and problems in quantum field theory. In India, the work was on refinements of the Diagonal Representation; group theoretical methods in problems of classical optics especially in dealing with partial coherence and polarization, and geometric phase theory. In the period 1979–1984 he inspired and led a group of physicists from USA, Sweden, Italy and India collaborating on problems in mechanics, mathematical physics and topological ideas in elementary particle theory. After about 1990, Sudarshan’s collaborations with physicists from Italy and Spain picked up in strength, the focus being mainly on quantum tomography, the Zeno effect and open system dynamics.
Controversy Regarding Nobel Prize
Sudarshan has been passed over for the Physics Nobel Prize on more than one occasion, leading to controversies. He, together with Robert Eugene Marshak, came out in 1957
with what is called the VA Theory of weak interactions. Three others, Sheldon Glashow, Abdus Salam and Steven Weinberg, developed it further. It eventually evolved as an electro weak theory of weak interactions. The three got the Nobel Prize for their work in 1979, but Sudarshan and Marshak got left behind. Sudarshan began working on quantum optics at the University of Rochester in 1960. Two years later, Glauber criticized the use of classical electromagnetic theory in explaining optical fields, but Sudarshan believed the theory provided accurate explanations. Sudarshan subsequently wrote a paper expressing his ideas and sent a preprint to Glauber. Glauber informed Sudarshan of similar results and asked to be acknowledged in the latter's paper, while criticizing Sudarshan in his own paper. "Glauber criticized Sudarshan’s representation, but his own was unable to generate any of the typical quantum optics phenomena, hence he introduces what he calls a P-representation, which was Sudarshan’s representation by another name", wrote a physicist. "This representation, which had at first been scorned by Glauber, later becomes known as the Sudarshan–Glauber representation."
Roy Glauber was awarded the Nobel Prize in 2005, but Sudarshan was not. Several physicists in 2005 wrote to the Swedish Academy, protesting that Sudarshan should have been
awarded a share of the Prize for the Sudarshan diagonal representation (also known as Sudarshan– Glauber representation) in quantum optics, for which Roy J. Glauber won his share of the prize. Sudarshan and others physicists sent a letter to the Nobel Committee claiming that the P representation had more contributions of "Sudarshan" than "Glauber". The letter goes on to say that Glauber criticized Sudarshan's theory—before renaming it the "P representation" and incorporating it into his own work. In an unpublished letter to The New York Times, Sudarshan calls the "Glauber– Sudarshan representation" a misnomer, adding that "literally all subsequent theoretic developments in the field of Quantum Optics make use of" Sudarshan's work— essentially, asserting that he had developed the breakthrough. In a letter to the Swedish Academy, Sudarshan said: “In the announcement of the 2005 Physics Nobel Prize, the Swedish Royal Academy has chosen RJ Glauber to be awarded half of the prize. The prize winners are chosen by the Royal Academy, but no one has the right to take my discoveries and formulations and ascribe them to someone else! The correct formulation of the quantum mechanical treatment of optics was carried out by me in my paper in 1963. In that I showed that every state can be represented in the diagonal form...This diagonal representation is valid for all fields. ......................................Give unto Glauber only what is his.”
Religion versus science
Born into a Syrian Christian family of Kerala, Sudarshan was unable to reconcile the Church and physics. He embraced aspects of Hinduism. Sudarshan practiced Vedanta, and delivered several lectures on the Vedantic school of philosophy. He was deeply interested in Malayalam literature and spoke in a vivid Kottayam accent as he went all over the world. He was deeply intrigued by Indic studies, and read classical Indian texts avidly in conjunction with philosophical treatises.
Awards
C V Raman Award, 1970.
Padma Bhushan, third highest civilian award from the Government of India, 1976.
Bose Medal of Indian National Science Academy, 1977.
TWAS Prize, 1985.
Desikotthama Award of Visva Bharati, 1998.
Padma Vibhushan, second highest civilian award from the Government of India, 2007.
Majorana Prize, 2006.
Dirac Medal of the ICTP, 2010.Kerala Sastra Puraskaram for lifetime accomplishments in science, 2013vOn 16 September 2011, The Institute of Mathematical Sciences (IMSc), Chennai organised av‘Sudarshan Fest’ to honour Prof. E.C.G. Sudarshan on his 80th birthdayGeorge Sudarshan was elected to the Indian Academy of Sciences and the
Indian National Science Academy in 1963 and 1972 respectively. In 1987, he was elected to the Academie Internationale de Philosophie des Sciences. From about 2010, his health began to fail. The end came on 13 May 2018 in Austin, Texas.
