Our Mathematical Universe is a journey to explore the mysteries uncovered by cosmology and to discover the nature of reality. Our Big Bang, our distant future, parallel worlds, the sub-atomic and intergalactic - none of them are what they seem. But there is a way to understand this immense strangeness - mathematics. Seeking an answer to the fundamental puzzle of why our universe seems so mathematical, Tegmark proposes a radical idea: that our physical world not only is described by mathematics, but that it is mathematics. This may offer answers to our deepest questions: How large is reality? What is everything made of? Why is our universe the way it is?Table of ContentsPreface1 What Is Reality?Not What It Seems What’s the Ultimate Question? The Journey BeginsPart One: Zooming Out2 Our Place in SpaceCosmic Questions How Big Is Space? The Size of Earth Distance to the Moon Distance to the Sun and the Planets Distance to the Stars Distance to the Galaxies What Is Space?3 Our Place in TimeWhere Did Our Solar System Come From? Where Did theGalaxies Come From? Where Did the Mysterious MicrowavesCome From? Where Did the Atoms Come From?4 Our Universe by NumbersWanted: Precision Cosmology Precision Microwave-Background Fluctuations Precision Galaxy Clustering The Ultimate Map of Our Universe Where Did Our Big Bang Come From?5 Our Cosmic OriginsWhat’s Wrong with Our Big Bang? How Inflation Works The Gift That Keeps on Giving Eternal Inflation6 Welcome to the MultiverseThe Level I Multiverse The Level II Multiverse Multiverse Halftime RoundupPart Two: Zooming In7 Cosmic LegosAtomic Legos Nuclear Legos Particle-Physics Legos Mathematical Legos Photon Legos Above the Law? Quanta and Rainbows Making Waves Quantum Weirdness The Collapse of Consensus The Weirdness Can’t Be Confined Quantum Confusion8 The Level III MultiverseThe Level III Multiverse The Illusion of Randomness Quantum Censorship The Joys of Getting Scooped Why Your Brain Isn’t a Quantum Computer Subject, Object and Environment Quantum Suicide Quantum Immortality? Multiverses Unified Shifting Views: Many Worlds or Many Words?Part Three: Stepping Back9 Internal Reality, External Reality and Consensus RealityExternal Reality and Internal Reality The Truth, the Whole Truth and Nothing but the Truth Consensus Reality Physics: Linking External to Consensus Reality10 Physical Reality and Mathematical RealityMath, Math Everywhere! The Mathematical Universe Hypothesis What Is a Mathematical Structure?11 Is Time an Illusion?How Can Physical Reality Be Mathematical? What Are You? Where Are You? (And What Do You Perceive?) When Are You?12 The Level IV MultiverseWhy I Believe in the Level IV Multiverse Exploring the Level IV Multiverse: What’s Out There? Implications of the Level IV Multiverse Are We Living in a Simulation? Relation Between the MUH, the Level IV Multiverse and Other Hypotheses Testing the Level IV Multiverse13 Life, Our Universe and EverythingHow Big Is Our Physical Reality? The Future of Physics The Future of Our Universe—How Will It End? The Future of Life The Future of You—Are You Insignificant?AcknowledgmentsSuggestions for Further ReadingIndex