Pallom is a village near Kottayam in central Kerala, in the backwater country where the state's dense network of schools and colleges took root earlier than in most of India. Ennackal Chandy George Sudarshan was born there on 16 September 1931, and went on to make contributions to theoretical physics that shaped the understanding of the weak nuclear force, of light itself, and of how quantum systems behave when they are watched. He is very widely regarded as the most distinguished physicist never to have received a Nobel Prize.

Kottayam to Rochester

Sudarshan was educated at CMS College in Kottayam and then at Madras Christian College, from which he graduated with honours in 1951, taking a master's degree from the University of Madras the following year. He spent a period at the Tata Institute of Fundamental Research in Bombay, where he came into contact with Homi Bhabha and the first generation of India's post-independence physics establishment.

In the mid-1950s he moved to the United States for doctoral work at the University of Rochester under Robert Marshak, completing his PhD in 1958. Rochester at that moment was one of the most important centres in the world for particle physics, and Sudarshan entered it as a graduate student at precisely the point when the structure of the weak interaction was in dispute.

The V-A theory

Working with Marshak in 1957, Sudarshan proposed that the weak nuclear force — the interaction responsible for radioactive beta decay — has a vector minus axial-vector structure, universally abbreviated as V-A. This was a fundamental result. It correctly identified the form of the weak interaction, accounted for the parity violation that had just been discovered, and became one of the foundation stones of what would eventually be assembled into the electroweak theory and the Standard Model of particle physics.

The idea was presented at a conference in Italy and shortly afterwards appeared in a widely read paper by Richard Feynman and Murray Gell-Mann. Because of the enormous visibility of those two authors, the V-A theory entered the textbooks strongly associated with their names. Marshak and Sudarshan's priority is acknowledged by historians of physics and was acknowledged by Feynman himself, but the popular attribution never fully corrected itself — the first of several occasions on which Sudarshan's work travelled further than his name.

Quantum optics, the Zeno effect and open systems

After postdoctoral work at Harvard with Julian Schwinger and a faculty position at Syracuse, Sudarshan moved to the University of Texas at Austin in 1969, where he remained a professor for the rest of his career while also holding senior positions in India, including several years as director of the Institute of Mathematical Sciences in Chennai and a professorship at the Indian Institute of Science.

His contributions across those decades were unusually wide:

The diagonal representation of quantum states of light, published in 1963, which demonstrated the equivalence between the classical wave description of optics and the full quantum treatment. It is now universally known as the Glauber-Sudarshan P representation and is the working tool of quantum optics.
The theory of tachyons, hypothetical particles travelling faster than light, developed with Olexa-Myron Bilaniuk and V. K. Deshpande, which explored whether such particles could exist without violating causality.
The no-interaction theorem of 1963, with Currie and Jordan, a foundational result on relativistic particle dynamics.
The quantum Zeno effect, proposed with Baidyanath Misra in 1977, showing that a quantum system observed sufficiently frequently is prevented from evolving at all — a result later confirmed experimentally and now central to quantum measurement theory.
The mathematics of open quantum systems, including the master equation now known as the GKSL or Lindblad equation, which underpins modern work on decoherence and quantum computing.

The Nobel question

Sudarshan was considered for the Nobel Prize on more than one occasion and never received it. The sharpest controversy came in 2005, when Roy Glauber was awarded the physics prize for work in quantum optics that rested on the representation Sudarshan had introduced. A number of physicists wrote publicly to the Nobel committee in protest, and Sudarshan himself stated plainly that the prize had been given for his work without being given to him. He made a similar observation regarding the 1979 award for electroweak theory, noting that those who lay a building's foundation are usually recognised before those who add later floors.

He did receive extensive honours: the Padma Bhushan in 1976, the Bose Medal, the first TWAS Prize in Physics in 1985, the Majorana Prize in 2006, the Padma Vibhushan in 2007 and the ICTP Dirac Medal in 2010.

Physics and philosophy

Sudarshan retained a lifelong engagement with Indian philosophical traditions, particularly Advaita Vedanta, and wrote and lectured on the relationship between the structure of physical theory and questions of consciousness and unity. He resisted any easy conflation of the two, but he treated both as serious enquiry rather than treating one as decoration for the other.

He died in Austin, Texas, on 13 May 2018, at the age of eighty-six. The boy from Pallom had left an imprint on at least four distinct areas of theoretical physics, several of which are named for other people.