Roger Penrose's original and provocative ideas about the physics of the Universe, quantum physics and the physics of the mind have been the subject of controversy and discussion. They were set forth in his best-selling books 'The Emperor's New Mind' and 'Shadow of the Mind'. In this book, he summarises and brings up to date his current thinking in these complex areas. Abner Shimony, Nancy Cartwright and Stephen Hawking scrutinise these ideas and present their own distinctive positions. Finally, Roger Penrose responds to their thought-provoking criticisms.This volume provides an accessible, illuminating and stimulating introduction to Roger Penrose's vision of theoretical physics for the 21st Century. His enthusiasm, insight and good humour shine through this brilliant account of the problems of modern physics.