The Road to Reality

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The Road to Reality:
A Complete Guide to the Laws of the Universe.
File:The Road to Reality.jpg
Hardcover edition
Author Roger Penrose
Country United States
Language English
Subject Modern physics
Genre Non-fiction
Publisher Alfred A. Knopf
Publication date
Later revised editions: 2005, 2006, 2007
Media type Print, e-book
Pages 1136 pp.
ISBN 978-0679454434
Preceded by Shadows of the Mind
Followed by Cycles of Time

The Road to Reality: A Complete Guide to the Laws of the Universe is a book on modern physics by the British mathematical physicist Roger Penrose, published in 2004.[1] It covers the basics of the Standard Model of particle physics, discussing general relativity and quantum mechanics, and discusses the possible unification of these two theories.


The book discusses the physical world. Many fields that 19th century scientists believed were separate, such as electricity and magnetism, are aspects of more fundamental properties. Some texts, both popular and university level, introduce these topics as separate concepts, and then reveal their combination much later. The Road to Reality reverses this process, first expounding the underlying mathematics of space–time, then showing how electromagnetism and other phenomena fall out fully formed.

The book is just over 1100 pages, of which the first 383 are dedicated to mathematics—Penrose's goal is to acquaint inquisitive readers with the mathematical tools needed to understand the remainder of the book in depth. Physics enters the discussion on page 383 with the topic of space–time. From there it moves on to fields in spacetime, deriving 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 Lagrangians and Hamiltonians, before moving on to a full discussion of quantum physics, particle theory and quantum field theory. A discussion of the measurement problem in quantum mechanics is given a full chapter; superstrings are given a chapter near the end of the book, as are loop gravity and twistor theory. The book ends with an exploration of other theories and possible ways forward.

The final chapters reflect Penrose's personal perspective, which differs in some respects from what he regards as the current fashion among theoretical physicists. He is skeptical about string theory, to which he prefers loop quantum gravity. He is optimistic about his own approach, twistor theory. He also holds some controversial views about the role of consciousness in physics, as laid out in his earlier books (see Shadows of the Mind).


So here, then, are all the laws of the universe, in one handy 1,100-page volume. It would appear that they are even more complicated than the laws of cricket, although just as necessary. Moreover, it says on the front cover that it is a "Sunday Times Top 10 Bestseller", and on the back, next to the price, that it is "popular science". Open it up at random and you will see that Jordan's autobiography this ain't. Your reaction, I suspect, may be closer to Nigel Molesworth's than you may like: "It's just a jumble of letters sir i mean i kno i couldn't care less whether i get it right or not but what sort of an ass sir can hav written this book."

—Nicholas Lezard, The Guardian[2]



  1. "The Road to Reality: A Complete Guide to the Laws of the Universe by Roger Penrose". Goodreads. Retrieved 18 November 2015.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  2. Lezard, Nicholas (11 February 2006). "Roger Penrose explains the laws of the universe in his monumental The Road to Reality. If only Nicholas Lezard could understand it". The Guardian. Retrieved 18 November 2015.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>

External links

  • Site with errata and solutions to some exercises from the first few chapters. Not sponsored by Penrose.
  • Archive of the Road to Reality internet forum, now defunct.
  • Solutions for many Road to Reality exercises.