pp. i-iv

pp. v-viii

#### Introduction

pp. 1-10

String theory is a mystery. It’s supposed to be the theory of everything. But it hasn’t been verified experimentally. And it’s so esoteric. It’s all about extra dimensions, quantum fluctuations, and black...

#### CHAPTER ONE: Energy

pp. 11-18

The aim of this chapter is to present the most famous equation of physics: E = mc2. This equation underlies nuclear power and the atom bomb. It says that if you convert one pound of matter entirely into...

#### CHAPTER TWO: Quantum Mechanics

pp. 19-33

After I got my bachelor’s degree in physics, I spent a year at Cambridge University studying math and physics. Cambridge is a place of green lawns and grey skies, with an immense, historical weight of...

#### CHAPTER THREE: Gravity and Black Holes

pp. 34-48

One fine summer day some years ago, I drove with my father up to Grotto Wall, a popular climbing crag near Aspen, Colorado. We aimed to climb a classic moderate route called Twin Cracks. After we...

#### CHAPTER FOUR: String Theory

pp. 49-68

When I was a sophomore at Princeton, I took a course on Roman history. It was mostly about the Roman Republic. It’s fascinating how the Romans combined peaceful and military achievements. They evolved an unwritten...

#### CHAPTER FIVE: Branes

pp. 69-98

In 1989, after my junior year in high school, I went to a physics camp. One of the things we did was to hear a lecture on string theory. About halfway through, one of the other students asked a sharp...

#### CHAPTER SIX: String Dualities

pp. 99-116

A duality is a statement that two apparently different things are equivalent. I already discussed one example in the introduction: a checkerboard. You can think of it as black squares on a red background, or as red squares on a black background. Those are “dual” descriptions of the same...

#### CHAPTER SEVEN: Supersymmetry and the LHC

pp. 117-139

In the summer of 2008, when the construction of the Large Hadron Collider, or LHC, was almost complete, I visited the site and took a tour of one of the main LHC experiments. Mostly I was...

#### CHAPTER EIGHT: Heavy Ions and the Fifth Dimension

pp. 140-158

A strange fact about the relation between supersymmetry and LHC physics is that the main ingredients were approximately in place twenty years ago or more. There have certainly been advances in the past...

#### Epilogue

pp. 159-162

There are many aspects of string theory we could ponder after the tour of the subject we have just completed. We could ponder the peculiar demands it seems to make on spacetime, like ten dimensions...

pp. 163-174