Cosmology is a branch of astronomy which deals with the origin and evolution of the universe. It involves the study of the universe right from the Big Bang to today and about the future. Intriguing concepts like string theory, Dark matter and dark energy and theory of alternate dimensions are studied under cosmology. Professor Raghavan Rangarajan discussed these concepts and answered related questions. Professor Raghavan Rangarajan is a professor at the School of Arts and Sciences and Dean of UnderGraduate college at Ahmedabad University.