The Road to Reality
The Road to Reality is a book on modern physics by the British mathematical physicist Roger Penrose, published in 2004. It covers the basics of the standard model of modern physics, discussing general relativity and quantum mechanics and then spending some time on the possible unification of these two theories. It is unusual in that it aims to be a popular science book, while not eschewing substantial amounts of mathematics that are required for relativity and quantum mechanics.
The book is just over 1100 pages, of which the first 350 or so are dedicated to mathematics. On page 383 physics enters the discussion with the topic of spacetime. From there it moves on to fields in spacetime, developing the classical electrical and magnetic forces from first principles; that is, if one lives in spacetime of a particular sort, these fields develop naturally as a consequence. Energy and conservation laws appear in the discussion of the Lagrangians and Hamiltonians, before moving onto a full discussion of quantum physics, particle theory and quantum field theory. The book ends with a lengthy exploration of other theories and possible ways forward, topics left out of most texts, or covered in "layman" books of dubious quality.
The book is original in that it discusses most of the physical world using modern language, thereby cutting away a tremendous amount of historical baggage. Many things that we formerly believed were separate, electricity and magnetism for instance, are facets of a single property, electromagnetism. Yet most texts, both popular and university level, still introduce these topics as separate concepts and then "force" the combination on them much later. In Road to Reality this process is reversed, by first demonstrating the math that is needed to discuss the spacetime we appear to live in, then showing that electromagnetism simply falls out fully formed. It may seem odd that the book covers so fundamental topic in a single chapter, yet given the extensive introduction in mathematics, this is arguably all that is needed.
Nor does the book shy from the problems modern physics tends to ignore. A discussion of the measurement problem in quantum mechanics is given a full chapter, although the discussion of various ontologies that attempt to address it is fairly limited. Nor are "failed" grand unified theory attempts ignored; while superstrings are given a chapter near the end of the book, so is loop gravity and twistors— in fact this may be the only popular discussion of twistor theory. This may not be so surprising, considering the twistor concept was developed by Penrose.
Book editions
- Alfred A. Knopf (publisher), February 2005, hardcover, ISBN 0679454438
- Vintage Books, February 2006, softcover, ISBN 0099440687