''The Road to Reality: A Complete Guide to the Laws of the Universe'' is a book on modern

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which relat ...

by the British mathematical physicist

Roger Penrose Sir Roger Penrose (born 8 August 1931) is an English mathematician, mathematical physicist, philosopher of science and Nobel Laureate in Physics. He is Emeritus Rouse Ball Professor of Mathematics in the University of Oxford, an emeritus fe ...

, published in 2004. It covers the basics of the

Standard Model The Standard Model of particle physics is the theory describing three of the four known fundamental forces (electromagnetic, weak and strong interactions - excluding gravity) in the universe and classifying all known elementary particles. It w ...

of particle physics, discussing

general relativity General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics. G ...

and

quantum mechanics Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, qu ...

, and discusses the possible unification of these two theories.

Overview

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 spacetime. From there it moves on to

fields Fields may refer to: Music *Fields (band), an indie rock band formed in 2006 *Fields (progressive rock band), a progressive rock band formed in 1971 * ''Fields'' (album), an LP by Swedish-based indie rock band Junip (2010) * "Fields", a song by ...

in spacetime, deriving the classical electrical and magnetic forces from

first principles In philosophy and science, a first principle is a basic proposition or assumption that cannot be deduced from any other proposition or assumption. First principles in philosophy are from First Cause attitudes and taught by Aristotelians, and nuan ...

; that is, if one lives in spacetime of a particular sort, these fields develop naturally as a consequence. Energy and

conservation law In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves over time. Exact conservation laws include conservation of energy, conservation of linear momentum, c ...

s appear in the discussion of Lagrangians and

Hamiltonian Hamiltonian may refer to: * Hamiltonian mechanics, a function that represents the total energy of a system * Hamiltonian (quantum mechanics), an operator corresponding to the total energy of that system ** Dyall Hamiltonian, a modified Hamiltonian ...

s, before moving on to a full discussion of quantum physics, particle theory and

quantum field theory In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines classical field theory, special relativity, and quantum mechanics. QFT is used in particle physics to construct physical models of subatomic particles and ...

. A discussion of the

measurement problem In quantum mechanics, the measurement problem is the problem of how, or whether, wave function collapse occurs. The inability to observe such a collapse directly has given rise to different interpretations of quantum mechanics and poses a key se ...

in quantum mechanics is given a full chapter;

superstring Superstring theory is an attempt to explain all of the particles and fundamental forces of nature in one theory by modeling them as vibrations of tiny supersymmetric strings. 'Superstring theory' is a shorthand for supersymmetric string t ...

s are given a chapter near the end of the book, as are

loop gravity Loop quantum gravity (LQG) is a theory of quantum gravity, which aims to merge quantum mechanics and general relativity, incorporating matter of the Standard Model into the framework established for the pure quantum gravity case. It is an attem ...

and

twistor theory In theoretical physics, twistor theory was proposed by Roger Penrose in 1967 as a possible path to quantum gravity and has evolved into a branch of theoretical and mathematical physics. Penrose proposed that twistor space should be the basic aren ...

. 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 Loop quantum gravity (LQG) is a theory of quantum gravity, which aims to merge quantum mechanics and general relativity, incorporating matter of the Standard Model into the framework established for the pure quantum gravity case. It is an attem ...

. He is optimistic about his own approach,

. 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 ''Shadows of the Mind: A Search for the Missing Science of Consciousness'' is a 1994 book by mathematical physicist Roger Penrose that serves as a followup to his 1989 book '' The Emperor's New Mind: Concerning Computers, Minds and The Laws of ...

'').

Reception

According to

Brian Blank Brian Blank (September 3, 1953 – December 9, 2018) was a Canadian/American associate professor of mathematics at Washington University in St. Louis. Blank was born in Montreal, Quebec, and earned an undergraduate degree in mathematics from McGil ...

: According to

Nicholas Lezard Nicholas Andrew Selwyn LezardThe Cambridge University List of Members up to 31 December 1991, Cambridge University Press, p. 814 is an English journalist, author and literary critic. Background and education The Lezard family went from London to Ki ...

: According to

Lee Smolin Lee Smolin (; born June 6, 1955) is an American theoretical physicist, a faculty member at the Perimeter Institute for Theoretical Physics, an adjunct professor of physics at the University of Waterloo and a member of the graduate faculty of the ...

: According to

Frank Wilczek Frank Anthony Wilczek (; born May 15, 1951) is an American theoretical physicist, mathematician and Nobel laureate. He is currently the Herman Feshbach Professor of Physics at the Massachusetts Institute of Technology (MIT), Founding Direct ...

Editions

*Jonathan Cape (1st edition), 2004, hardcover, *Alfred A. Knopf (publisher), February 2005, hardcover, *Vintage Books, 2005, softcover, *Vintage Books, 2006, softcover, *Vintage Books, 2007, softcover,

References

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. {{DEFAULTSORT:Road to Reality 2004 non-fiction books Alfred A. Knopf books Cosmology books Mathematics books Popular physics books Quantum mind String theory books Works by Roger Penrose