The Great Beyond: Higher dimensions, parallel universes and the extraordinary search for a theory of everything, Paul Halpern (ISBN 9780471741497, Trade Paper Press)

I got a tip about this book from somewhere I cannot remember. But it was a lucky tip. The book is basically a short history of what has lead us to string theory. It starts of with the mathematical extension of Euclidian geometry to more dimensions by Riemann and Gauss. Then the link is made to physics describing how Theodor Kaluza and Oscar Klein more or less discovered that by adding a fifth dimension they could unite gravity and the Maxwell equations of electromagnetism. The middle section of the book discusses Einstein’s efforts to find a unifying theory that would get rid of the probabilities in quantum mechanics. At the time most people found it a futile effort but later on, after the weak interaction and electromagnetism were unified it became a topic of interest again. The book then goes on to discuss the problems with relativity and ideas to extend the theory so it can become a part of a Theory of Everything or a Grand Unifying Theory. Supersymmetry, supergravity and quantum gravity pass the revue and as such the search expands to 11 dimensions. Efforts starting from the quantum theory side trying to unite quantum electrodynamics with th weak and strong force almost ‘naturally’ lead to string theories of 11 and 26 dimensions. Through the course of the book also the most important contributors are introduced adding some human elements to the story.The book focuses on how and why physicists became interested in more dimensions and also discusses how the idea of more dimensions had an influence on society and art. The book is well written and I enjoyed reading it. It is high level and doesn’t discuss technical details. Depending on your background and inclination you may like this or not. For me this works well as my educational background and reading allow me to fill in gaps that are not mentioned or explained. I learned many unexpected things and came away with a renewed interest and motivation to finally attack one of my schoolday textbooks on gravity.