This volume is a collection of essays written in honour of Professor P.C. Vaidya and Professor A.K. Raychaudhuri. These two distinguished scientists are well-known for their important contributions to general relativity and cosmology, and are widely respected as inspiring teachers. Topics in general relativity fall broadly into two types namely the study of gravitational effects around local objects and the investigation of the global structure of spacetime. The Vaidya metric is an example of the former while the Raychaudhuri equation belongs to the latter category. Appropriately, the articles in this volume highlight problems of both kinds and are written by experts in the respective fields. These essays span a wide spectrum of diverse areas from abstract concepts to observational techniques within the framework of relativity, cosmology and astrophysics. Some of them represent original results of recent research, while others are broad-based state of the art reviews.
The variety of subjects discussed here includes the detection of gravitational radiation, structure of spacetimes, the nature of singularities, positivity of gravitational energy, relativistic astrophysics in relation to gravitational collapse, neutron stars and black holes and fundamental conceptual problems in general relativity and cosmology. General relativity and associated fields constitute today a rapidly expanding area of research. A Random Walk in Relativity and Cosmology, by presenting new ideas and offering a glimpse of the excitement of ongoing exploration, should be both useful and stimulating to any interested reader.