The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory (1999) is physicist and string theorist Brian Greene’s first popular science book, which attempts to present the complex and esoteric ideas of superstring theory to a nonacademic audience. Widely regarded as one of the best popular science books, The Elegant Universe launched Greene’s career as a public intellectual, speaker, and educator. He has written five nonfiction books and one science-related children’s fiction book; in addition, he has contributed to several PBS specials and has made several television guest appearances.

In The Elegant Universe, Greene gives an overview of the foundations of physics, including Newtonian gravity, particle physics, and Albert Einstein’s theories of special and general relativity. Greene then moves on to the complex realm of quantum mechanics, focusing on the fundamental incompatibility between general relativity and quantum theory and how this conflict hinders the search for a unifying theory of physics, which is a goal of many theorists. Brian Greene and other physicists propose string theory as the answer to this need for unification.

The Elegant Universe was a finalist for the Pulitzer Prize in nonfiction the year it was published, and won the Aventis Prize for Science Books in 2000. It was turned into a PBS television special of the same title, which Greene himself hosted and narrated, winning a Peabody Award for his work in 2003 (“Award Profile for NOVA: The Elegant Universe with Brian Greene.” The Peabody Awards).

This study guide uses the paperback Vintage Books edition published in 2000.

Summary

In the Preface, Greene explains that his impetus for writing The Elegant Universe is to argue for string theory as the best answer to the search for a unifying theory. Additionally, he hopes to make the complex and esoteric concepts involved—such as relativity and quantum mechanics—accessible to a general audience. Greene then moves to Part 1, which is a single chapter. In it, Greene introduces the basic concepts of particle physics to lay the groundwork of the theories that follow. He explains the three families of matter particles, the four forces at work in the universe, and the three major conflicts within physics, each of which the next three chapters discuss in detail.

Part 2 is a crash course in modern theoretical physics, focusing on special relativity, general relativity, and quantum mechanics and how these developments led to the three conflicts. In Chapter 2, Greene explains the first conflict between the Newtonian laws of motion and Maxwell’s electromagnetism. Einstein’s theory of special relativity, which established light speed and the famous equation E=mc², resolved this conflict. This led to the second major conflict, discussed in Chapter 3, between special relativity and Newtonian gravitation. To resolve this conflict, Einstein proposed the theory of general relativity, which explained the effects of gravity. Chapter 4 summarizes the theory of quantum mechanics, which deals with the realm of microscopic particles and the uncertainty principle. In Chapter 5, Greene explains the third and current conflict in physics, which is the incompatibility between general relativity and quantum mechanics.

Part 3 explains string theory, including how it may resolve the conflict between relativity and quantum mechanics. Chapter 6 focuses on the history and initial development of string theory, and the basic principle that the universe is composed of strings that vibrate in specific patterns. Chapters 7 and 8 delve into the theory’s more abstract elements, such as supersymmetry and Calabi-Yau shapes. Chapter 9 explains some of the challenges in testing or proving string theory, as well as avenues for further experimentation.

In Part 4, Greene examines the consequences of string theory on the biggest questions of physics, particularly how it shifts the understanding of spacetime, black holes, and the big bang. First, as Chapter 10 details, the complex dimensions of string theory require a new field of mathematics called quantum geometry. Chapter 11 examines what string theory suggests about the fabric of spacetime and describes Greene’s work in studying spacetime tears. Chapter 12 details the contributions of theoretical physicist Edward Witten, particularly his proposal that the five competing versions of string theory may be combined into one overarching framework called M-theory. In Chapters 13 and 14, Greene combines these concepts to explain what string theory suggests about what a black hole is, what happens when one opens, and what the first moments of the big bang might have looked like.

Greene concludes with the single chapter of Part 5, in which he acknowledges the obstacles and shortcomings of string theory, and proposes five questions that must be answered to validate string theory. He offers his hopes for how those answers might be found and how string theory research may expand in the coming years.