I am an alumnus of the Indian Institute of Technology, Kharagpur (1969-74) and received my PhD (1982) at the Tata Institute of Fundamental Research, Bombay, where I was a staff member (1979-84). Subsequently I held visiting positions at CERN, Oxford Astrophysics, Rutherford Appleton Laboratory, and worked in science education for the NGO Eklavya, Bhopal. Since 1990 I have been at the Rudolf Peierls Centre for Theoretical Physics, Oxford - as Glasstone Research Fellow, then PPARC Advanced Fellow, appointed Lecturer (1998) and Professor (2006). I was Head of the Particle Theory Group (2011-19) and Niels Bohr Professor at Copenhagen (2013-18).
My interests are at the interface of fundamental physics with astrophysics & cosmology - dark matter, dark energy, inflation & the cosmic microwave background, neutrinos, primordial nucleosynthesis, relic topological defects etc. I also work on high energy cosmic rays, neutrinos & gamma-rays, and belong to the IceCube Neutrino Observatory & the Cherenkov Telescope Array collaborations. Earlier I worked on the Pierre Auger Observatory & the BEBC Beam Dump experiment at CERN. I participate in the Quantum Sensors for the Hidden Sector programme and in laboratory experiments using high powered lasers to investigate astrophysical processes.