This is the third edition of the classic book The Nature of Physical Reality that presents current knowledge of physics and highlights significant Indian contributions to the subject. The book is as much about what is known as about what remains to be known and it speaks of a variety of paradoxes of mathematics and physics. It argues that there is a hidden order in physical reality that transcends the capacity of rational models and suggests that new research has the potential to illuminate the mystery of consciousness. Subhash Kak is Regents Professor at Oklahoma State University at Stillwater. Born in Srinagar, Kashmir, he completed his Ph.D. at Indian Institute of Technology, Delhi. Apart from his contributions to quantum information and computer science, he has worked on history and philosophy of science.