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Introduction 1 About This Book 1 Conventions Used in This Book 2 What You''re Not to Read 3 Foolish Assumptions 3 How This Book Is Organized 4
Part I: Introducing String Theory 4
Part II: The Physics Upon Which String Theory Is Built 4
Part III: Building String Theory: A Theory of Everything 5
Part IV: The Unseen Cosmos: String Theory on the Boundaries of Knowledge 5
Part V: What the Other Guys Say: Criticism and Alternatives 5
Part VI: The
Part of Tens 5 Icons Used in this Book 6 Where to Go from Here 6
Part I: Introducing String Theory 7
Chapter 1: So What Is String Theory Anyway? 9 String Theory: Seeing What Vibrating Strings Can Tell Us about the Universe 9 Using tiny and huge concepts to create a theory of everything 10 A quick look at where string theory has been 11 Introducing the Key Elements of String Theory 12 Strings and branes 12 Quantum gravity 14 Unification of forces 14 Supersymmetry 15 Extra dimensions 15 Understanding the Aim of String Theory 16 Explaining matter and mass 16 Defining space and time 17 Quantizing gravity 18 Unifying forces 18 Appreciating the Theory''s Amazing (and Controversial) Implications 19 Landscape of possible theories 19 Parallel universes 20 Wormholes 20 The universe as a hologram 21 Time travel 21 The big bang 21 The end of the universe 22 Why Is String Theory So Important? 22
Chapter 2: The Physics Road Dead Ends at Quantum Gravity 25 Understanding Two Schools of Thought on Gravity 26 Newton''s law of gravity: Gravity as force 26 Einstein''s law of gravity: Gravity as geometry 28 Describing Matter: Physical and Energy-Filled 28 Viewing matter classically: Chunks of stuff 29 Viewing matter at a quantum scale: Chunks of energy 29 Grasping for the Fundamental Forces of Physics 30 Electromagnetism: Super-speedy energy waves 30 Nuclear forces: What the strong force joins, the weak force tears apart 31 Infinities: Why Einstein and the Quanta Don''t Get Along 32 Singularities: Bending gravity to the breaking point 33 Quantum jitters: Space-time under a quantum microscope 33 Unifying the Forces 35 Einstein''s failed quest to explain everything 35 A particle of gravity: The graviton 36 Supersymmetry''s role in quantum gravity 37
Chapter 3: Accomplishments and Failures of String Theory 39 Celebrating String Theory''s Successes 39 Predicting gravity out of strings 40 Explaining what happens to a black hole (sort of) 40 Explaining quantum fi eld theory using string theory 41 Like John Travolta, string theory keeps making a comeback 41 Being the most popular theory in town 42 Considering String Theory''s Setbacks 43 The universe doesn''t have enough particles 43 Dark energy: The discovery string theory should have predicted 44 Where did all of these "fundamental" theories come from? 45 Looking into String Theory''s Future 45 Theoretical complications: Can we figure out string theory? 46 Experimental complications: Can we prove string theory? 46
Part II: The Physics upon Which String Theory is Built 49
Chapter 4: Putting String Theory in Context: Understanding the Method of Science 51 Exploring the Practice of Science 52 The myth of the scientific method 52 The need for experimental falsifiability 53 The foundation of theory is mathematics 55 The rule of simplicity 56 The role of objectivity in science 57 Understanding How Scientific Change Is Viewed 57 Old becomes new again: Science as revolution 58 Combining forces: Science as unification 59 What happens when you break it? Science as symmetry 60
Chapter 5: What You Must Know about Classical Physics 63 This Crazy Little Thing Called Physics 63 No laughing matter: What we''re made of 64 Add a little energy: Why stuff happens 66 Symmetry: Why some laws were made to be broken 67 All Shook Up: Waves and Vibrations 68 Catching the wave 69 Getting some good vibrations 70 Newton''s Revolution: How Physics Was Born 72 Force, mass, and acceleration: Putting objects into motion 73 Gravity: A great discovery 74 Optics: Shedding light on light''s properties 75 Calculus and mathematics: Enhancing scientific understanding 75 The Forces of Light: Electricity and Magnetism 75 Light as a wave: The ether theory 76 Invisible lines of force: Electric and magnetic fields 76 Maxwell''s equations bring it all together: Electromagnetic waves 79 Two dark clouds and the birth of modern physics 80
Chapter 6: Revolutionizing Space and Time: Einstein''s Relativity 81 What Waves Light Waves? Searching for the Ether 82 No Ether? No Problem: Introducing Special Relativity 84 Unifying space and time 85 Unifying mass and energy 87 Changing Course: Introducing General Relativity 89 Gravity as acceleration 89 Gravity as geometry 91 Testing general relativity 92 Applying Einstein''s Work to the Mysteries of the Universe 95 Kaluza-Klein Theory -- String Theory''s Predecessor 96
Chapter 7: Brushing Up on Quantum Theory Basics 99 Unlocking the First Quanta: The Birth of Quantum Physics 100 Fun with Photons: Einstein''s Nobel Idea of Light 102 Waves and Particles Living Together 105 Light as a wave: The double slit experiment 105 Particles as a wave: The de Broglie hypothesis 106 Quantum physics to the rescue: The quantum wavefunction 108 Why We Can''t Measure It All: The Uncertainty Principle 109 Dead Cats, Live Cats, and Probability in Quantum Physics 111 Does Anyone Know What Quantum Theory Means? 112 Interactions transform quantum systems: The Copenhagen interpretation 113 If no one''s there to see it, does the universe exist? The participatory anthropic principle 113 All possibilities take place: The many worlds interpretation 114 What are the odds? Consistent histories 115 Searching for more fundamental data: The hidden variables interpretation 115 Quantum Units of Nature -- Planck Units 116
Chapter 8: The Standard Model of Particle Physics 119 Atoms, Atoms, Everywhere Atoms: Introducing Atomic Theory 120 Popping Open the Atomic Hood and Seeing What''s Inside 121 Discovering the electron 122 The nucleus is the thing in the middle 123 Watching the dance inside an atom 123 The Quantum Picture of the Photon: Quantum Electrodynamics 125 Dr. Feynman''s doodles explain how particles exchange information 125 Discovering that other kind of matter: Antimatter 127 Sometimes a particle is only virtual 128 Digging into the Nucleus: Quantum Chromodynamics 129 The pieces that make up the nucleus: Nucleons 129 The pieces that make up the nucleon''s pieces: Quarks 130 Looking into the Types of Particles 131 Particles of force: Bosons 131 Particles of matter: Fermions 132 Gauge Bosons: Particles Holding Other Particles Together 133 Exploring the Theory of Where Mass Comes From 134 From Big to Small: The Hierarchy Problem in Physics 135
Chapter 9: Physics in Space: Considering Cosmology and Astrophysics 137 Creating an Incorrect Model of the Universe 138 Aristotle assigns realms to the universe 138 Ptolemy puts Earth at the center of the universe (and the Catholic Church agrees) 139 The Enlightened Universe: Some Changes Allowed 141 Copernicus corrects what''s where in the universe 141 Beholding the movements of heavenly bodies 142 Introducing the Idea of an Expanding Universe 143 Discovering that energy and pressure have gravity 143 Hubble drives it home 145 Finding a Beginning: The Big Bang Theory 146 Bucking the big bang: The steady state theory 147 Going to bat for the big bang: Cosmic microwave background radiation 148 Understanding where the chemical elements came from 150 Using Inflation to Solve the Universe''s Problems of Flatness and Horizon 150 The universe''s issues: Too far and too flat 151 Rapid expansion early on holds the solutions 152 Dark Matter: The Source of Extra Gravity 153 Dark Energy: Pushing the Universe Apart 153 Stretching the Fabric of Space-Time into a Black Hole 156 What goes on inside a black hole? 156 What goes on at the edge of a black hole? 157
Part III: Building String Theory: A Theory of Everything 159
Chapter 10: Early Strings and Superstrings: Unearthing the Theory''s Beginnings 161 Bosonic String Theory: The First String Theory 161 Explaining the scattering of particles with early dual resonance models 162 Exploring the first physical model: Particles as strings 164 Bosonic string theory loses out to the Standard Model 165 Why Bosonic String Theory Doesn''t Describe Our Universe 166 Massless particles 166 Tachyons 167 No electrons allowed 168 25 space dimensions, plus 1 of time 168 Supersymmetry Saves the Day: Superstring Theory 170 Fermions and bosons coexist sort of 171 Double your particle fun: Supersymmetry hypothesizes superpartners 172 Some problems get fixed, but the dimension problem r