While much of the book is a helpful summary of key topics in math and physics, the real value of this book is in the last few chapters. There Penrose describes in detail the fashionable theories of the day, namely string theory, super-symmetry and inflation from the perspective of someone who is has been immersed in advanced physics and made valuable contributions for half a century. Penrose points out the dearth of evidence  that actually support those huge investments of intellectual capital and compares them to other theories that also started out on the promise of mathematical beauty but were abandoned. He gives some space to his own twistor theory, which he has devoted so many decades to, in a way that shows great humility. The result is a fine testament to the devotion of so many great minds to understanding the universe.<br><br>I read this book to gain a sense of the state of the world of physics, and I was not disappointed. The most intriguing part was a section that mentioned some recent work by Witten in string theory that uses twistors to bring string theory back to our own world of 3+1 dimensions, and at the same time invokes supersymmetry only to remove an anomoly. Penrose had carefully shown how other approaches to remove anomolies had changed over time, so the implication to all the effort spent in supersymmetry is clear. Penrose nicely describes the difficulties this field poses to young physicists whose funding is decided by those with so many years invested in other theories. The Reality that this book is a Road to is the reality of the world of physicists more than of the universe.<br><br>This book is a refreshing change from other books which portray other approaches as the pinnacle of human development (see M-theory). I hope the approach taken in this book spreads and reduces the tendency to portray science has having everything understood but a few odds and ends. The chapters where Penrose pokes numerous holes in string theory and inflation were quite entertaining, and could serve as a model for more accurate portrayal of the world of science. This approach could encourage young people to feel they could make a contribution rather than just be saddled with patching up little corners of supposedly established dogma.