Jayant Vishnu Narlikar (born 19 July 1938) is an Indian astrophysicist and emeritus professor at the Inter-University Centre for Astronomy and Astrophysics (IUCAA). He developed with Sir Fred Hoyle the conformal gravity theory, known as Hoyle–Narlikar theory. It synthesises Albert Einstein's theory of relativity and Mach's principle. It proposes that the inertial mass of a particle is a function of the masses of all other particles, multiplied by a coupling constant, which is a function of cosmic epoch.