Vishveshwara’s most renowned work is the discovery of the quasi-normal modes of black holes. In 1970, he showed that a Schwarzschild black hole perturbed by a pulse of gravitational radiation will go back to its original state by emitting gravitational waves of a simple, characteristic form, called quasi normal modes. The (complex) frequencies of the quasi normal modes of Schwarzschild black holes are independent of the nature of the perturbation and are fully characterized by the mass of the black hole. Later, this result was generalized to the case of rotating (Kerr) black holes as well. Here, the quasi-normal modes are functions of the mass and the spin angular momentum of the black hole. The observation of quasi-normal modes is considered as the smoking gun evidence of a black hole. Recently, the first observation of gravitational waves by LIGO gave us the first potential observational glimpse of quasi-normal modes. The final part of the observed signal, produced by the coalescence of two black holes, is fully consistent with what we expect from the quasi-normal mode ringing of a perturbed black hole produced by the merger.
Vishu, as he was popularly known, inspired several generations of Indian physicists, especially relativists. The founding director and lifelong patron of the Jawaharlal Nehru Planetarium in Bangalore, Vishu was deeply committed to the spread of scientific temper and knowledge. A cartoonist par excellence, Vishu had a remarkable sense of humour. While his friends, colleagues and students mourn the loss of Vishu, they also celebrate his life and work.
Further reading
- C.V. Vishveshwara: the black hole man of India
- Remembering C.V. Vishveshwara, the Quasimodo of Black Holes
- C.V. Vishveshwara – Quasimodo of black holes
- Collection of articles on and by C. V. Vishveshwara
- Black Holes, Gravitational Radiation and the Universe: Essays in Honor of C.V. Vishveshwara
Some classic papers of Vishveshwara
- Generalization of the "Schwarzschild Surface" to Arbitrary Static and Stationary Metrics, C. V. Vishveshwara, J Math. Phys., 9, 1319 (1968),
- Stability of the Schwarzschild Metric, C. V. Vishveshwara, Phys. Rev. D, 1, 2870 (1970),
- Scattering of Gravitational Radiation by a Schwarzschild BlackHole, C. V. Vishveshwara, Nature, 227, 936 (1970)
- The Rest Frame in Stationary Space-times with Axial Symmetry, R. D. Greene, E. L. Schucking and C. V. Vishveshwara, J. Math. Phys. 16, 153 (1975),