Einstein's Centennial gift: Gravitational Waves Discovered

Abstract: Gravitational waves have been detected by the LIGO detectors in US. The discovery was announced on the 11th of February 2016. A century ago - in 1916 - Einstein predicted the existence of gravitational waves. The existence of the waves was established by the observations of the Hulse-Taylor binary pulsar whose orbit decays exactly as predicted by Einstein's general theory of relativity. Much before this, pioneering efforts by Joe Weber began in the 1960s for detecting these waves using resonant mass detectors. Weakness of the gravitational force implies that the waves are extremely difficult to detect - one must effectively measure distances much smaller than the size of a proton. During the past half century, technology has taken immense strides and the current advanced detectors are now capable of reaching the requisite sensitivity to detect the waves. Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot be otherwise obtained. A new astronomical window to the universe has been opened. This talk will describe the physics of gravitational waves, the technological feats necessary for the detector to achieve unprecedented sensitivities, the current & future global efforts in this direction, the description of the gravitational wave event that was detected, the Indian contribution to the global effort and the astrophysics we can learn from this.

About the Speaker: Prof. Sanjeev Dhurandhar is an emeritus professor at Inter-University Center for Astronomy and Astrophysics (IUCAA), Pune

In 1989, he joined IUCAA as an Assistant Professor where he started a group on Gravitational Waves. For close to two decades, his was the only group in India working on Gravitational Wave Detection problems. Along with his Ph.D. students and Post-doctoral fellows, he addressed some of the demanding problems in the field of Gravitational Wave Physics.

To name a few of his contributions; a matched filter technique developed with his Postdoctoral fellow Prof. Sathyaprakash (who leads the group at Cardiff University), Stationary Phase Approximation used in template models, differential geometric approach to the metric based gravitational wave search, the Coherent Multi-detector approach, Hierarchical Schemes in gravitational wave search, Radiometric search in stochastic background search and algebraic geometric approach to the LISA data analysis problem. He is the pioneer of the field of Gravitational Wave Detection in India. Prof. Dhurandhar is one of the proposers of the Laser Interferometer Gravitational-wave Observatory (LIGO)-India project whose goal is to build a laser interferometric gravitational wave observatory in Indian soil. LIGO-India is planned as a collaborative project between India and the LIGO Laboratory of the USA. The LIGO-India project has received an in-principle approval from the PMO's office on 17th February 2016.