The author of this book – Mohammad Masroor Ahmed, is an Associate Professor at Mirza Ghalib College, Gaya (affiliated to Magadh University, Body Gaya). He has 37 years of teaching experience at both U.G and P.G levels. He has been a Guest Faculty at Magadh University for more than a decade, covering subjects such as Mathematical Physics, Quantum Mechanics, Quantum Field Theory, General Theory of Relativity, and Theoretical Nuclear Physics as an elective paper. This book is an outcome of his teachings and learnings along the way. The author is interested in popularising science. He has delivered several popular lectures and talks at his college and university)