Our Mathematical Universe: My Quest for the Ultimate Nature of Reality

Cover
Copyright
Contents
Preface
1 What Is Reality?
	Not What It Seems
	What\'s the Ultimate Question?
	The Journey Begins
	THE BOTTOM LINE
Part One Zooming Out
2 Our Place in Space
	Cosmic 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?
	THE BOTTOM LINE
3 Our Place in Time
	Where Did Our Solar System Come From?
	Where Did the Galaxies Come From?
		Galaxy Formation
		Our Universe Could Be Expanding
		Our Universe Is Expanding
		Making Sense of an Expanding Universe
		What’s Our Universe Expanding Into?
		The Cosmic Classroom
	Where Did the Mysterious Microwaves Come From?
		The Cosmic Plasma Screen
		Seeing the Afterglow
		Baby Pictures of Our Universe
		The Gold Rush
		The Cosmic Beach Ball
		A Microwave Background Comes of Age
	Where Did the Atoms Come From?
		The Cosmic Fusion Reactor
		Big Bang in Trouble
		What Is a Big Bang, Really?
	THE BOTTOM LINE
4 Our Universe by Numbers
	Wanted: Precision Cosmology
	Precision Microwave-Background Fluctuations
		Telescopes and Computers
		Gold in the Hills
		Dark Energy
		A 50% Batting Average
	Precision Galaxy Clustering
		From Derision Cosmology to Precision Cosmology
	The Ultimate Map of Our Universe
		A Lot Left to Explore
		Hydrogen Mapping
		What Is a Telescope, Really?
		The Omniscope
	Where Did Our Big Bang Come From?
	THE BOTTOM LINE
5 Our Cosmic Origins
	What’s Wrong with Our Big Bang?
		The Horizon Problem
		The Flatness Problem
	How Inflation Works
		The Power of Doubling
		Problems Solved
		Who Paid for the Ultimate Free Lunch?
	The Gift That Keeps on Giving
		Inflation Encore
		Sowing the Seed Fluctuations
	Eternal Inflation
		Unstoppable
		How to Make an Infinite Space in a Finite Volume
	THE BOTTOM LINE
6 Welcome to the Multiverse
	The Level I Multiverse
		What’s a Universe?
		What Are Level I Parallel Universes Like?
		Are Parallel Universes Unscientific?
		Evidence for Level I Parallel Universes
		Where Are the Level I Parallel Universes?
	The Level II Multiverse
		Many Universes in One Space
		Diversity!
		Fine-Tuning as Evidence for the Level II Multiverse
		Fine-Tuned Dark Energy
		Fine-Tuned Cosmology
		The Fluke Explanation
		The A Word
		What Can We Ever Hope to Predict?
		All Isn’t Lost
	Multiverse Halftime Roundup
	THE BOTTOM LINE
Part Two Zooming In
7 Cosmic Legos
	Atomic 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 Confusion
	THE BOTTOM LINE
8 The Level III Multiverse
	The 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?
	THE BOTTOM LINE
Part Three Stepping Back
9 Internal Reality, External Reality and Consensus Reality
	External Reality and Internal Reality
	The Truth, the Whole Truth and Nothing but the Truth
	Consensus Reality
	Physics: Linking External Reality to Consensus Reality
	THE BOTTOM LINE
10 Physical Reality and Mathematical Reality
	Math, Math Everywhere!
		Shapes, Patterns and Equations
		Numbers
		More Clues
	The Mathematical Universe Hypothesis
		Reducing the Baggage Allowance
		Mathematical Structures
	What Is a Mathematical Structure?
		Baggage and Equivalent Descriptions
		Baggage and Mathematical Structures
		Symmetry and Other Mathematical Properties
	THE BOTTOM LINE
11 Is Time an Illusion?
	How Can Physical Reality Be Mathematical?
		Timeless Reality
		Past, Present and Future
		How Spacetime and “Stuff” Can Be Mathematical
		Description Versus Equivalence
	What Are You?
		The Braid of Life
		Living in the Moment
		Self-Awareness
		Predicting Your Future
	Where Are You? (And What Do You Perceive?)
		Predicting Your Future, Revisited
		Finding Self-Awareness
		Computing the Internal Reality: What Has History Taught Us?
			Don’t panic
			We perceive that which is stable
			We perceive ourselves as local
			We perceive ourselves as unique
			We perceive ourselves as immortal(?)
			We perceive that which is useful
			We perceive that for which awareness is needed
	When Are You?
		Beyond Popper’s Two-Timing
		Why Aren’t You an Ant?
		Why Aren’t You a Boltzmann Brain?
		The Doomsday Argument: Is the End Nigh?
		Why Is Earth So Old?
		Why Aren’t You Younger?
		The Measure Problem: Physics in Crisis
		Infinite Problems
	THE BOTTOM LINE
12 The Level IV Multiverse
	Why I Believe in the Level IV Multiverse
		Why These Equations, Not Others?
		Mathematical Democracy
		How the Mathematical Universe Hypothesis Implies the Level IV Multiverse
	Exploring the Level IV Multiverse: What’s Out There?
		Our Local Neighborhood
		Our Postal Code in the Level IV Multiverse
		The Structure of the Level IV Multiverse
		Limits of the Level IV Multiverse: Undecidable, Uncomputable and Undefined
		The Computable Universe Hypothesis
		The Transcendent Structure of Level IV
	Implications of the Level IV Multiverse
		Symmetries and Beyond
		The Illusion of Initial Conditions
		The Illusion of Randomness
		The Illusion of Complexity
		Initial Conditions Reinterpreted
		Randomness Reinterpreted
		How Complexity Suggests a Multiverse
	Are We Living in a Simulation?
		The Time Misconception
		A Different Sort of Computation
		Does a Simulation Really Need to Be Run?
	Relation Between the MUH, the Level IV Multiverse and Other Hypotheses
	Testing the Level IV Multiverse
		The Typicality Prediction
		The Mathematical-Regularity Prediction
	THE BOTTOM LINE
13 Life, Our Universe and Everything
	How Big Is Our Physical Reality?
		The Case for a Smaller Reality
		The Case for a Greater Reality
	The Future of Physics
	The Future of Our Universe—How Will It End?
	The Future of Life
		Existential Risk
		Our Dying Sun
		Asteroids, Supernovae and Supervolcanoes
		Self-Inflicted Problems
		Accidental Nuclear War
		An Unfriendly Singularity
			The singularity idea
			Who controls the singularity?
			The internal reality of ultra-intelligent life
			Reactions to the singularity
		Human Stupidity: A Cosmic Perspective
		Human Society: A Scientific Perspective
	The Future of You—Are You Insignificant?
		The Meaning of Life
		Why We Should Care About Our Own Universe
		Are We Insignificant?
		Are We Alone?
		Are We Really Insignificant?
	THE BOTTOM LINE
Acknowledgments
Suggestionsfor Further Reading
	Cosmology (Chapters 2-4)
	Inflation, Multiverse Levels l-ll (Chapters 5-6)
	Quantum Mechanics, Multiverse Level III (Chapters 7-8)
	Multiverses in General (Chapters 6 and 8)
	The Mind (Chapters 9 and 11)
	Mathematics, Computation, Complexity (Chapters 10-12)
	Future of Life (Chapter 13)
	Fundamental Physics, String Theory, Quantum Gravity
Index
	A - B
	C
	D
	E
	F-G
	H-I
	J-K-L
	M
	N
	O-P
	Q
	R-S
	T
	U-V-W
	X-Y-Z
A Note About the Author
A Note on the Type