SUSHIL KUMAR SRIVASTAVA, Ph.D., is Professor, Department of Mathematics, North Eastern Hill University, Shillong. With more than two decades of teaching experience and three decades of research experience in General Relativity and Cosmology, he has published research articles on tachyon cosmology, quantum fields in curved space time, dual nature of the Ricci scalar and dark energy in leading national and international journals. A recipient of Honorable Mention from U.S. Gravity Research Foundation, Massachussetts and Meghnad Saha Award for theoretical sciences, Dr. Srivastava has also authored a book Aspects of Gravitational Interactions. Professor Srivastava is the life member of Indian Association of General Relativity and Gravitation, and Astronomical Society of India.