Musser G. Emergence in Condensed Matter and Quantum Gravity. A Nontechnical 2022

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This book surveys the science at a semipopular, Scientific American-level. It is even-handed with regard to competing directions of research and philosophical positions. It is hard to get even two people to agree on anything, yet a million billion water molecules can suddenly and abruptly coordinate to lock themselves into an ice crystal or liberate one another to billow outwards as steam. The marvelous self-organizing capacity of matter is one of the central and deepest puzzles of physics, with implications for all the natural sciences. Physicists in the past century have found a remarkable diversity of phases of matter―and equally remarkable commonalities within that diversity. The pace of discovery has, if anything, only quickened in recent years with the appreciation of quantum phases of matter and so-called topological order. The study of seemingly humdrum materials has made contact with the more exotic realm of quantum gravity, as theorists realize that the spacetime continuum may itself be a phase of some deeper and still unknown constituents. These developments flesh out the sometimes vague concept of the emergence―how exactly it is that complexity begets simplicity.
Acknowledgements
About the Author
Introduction
What is Emergence?
Is Emergence Fundamental?
Weak Versus Strong Emergence
References
Emergence in Condensed Matter Physics
Introduction
Just a Phase They’re Going Through—Landau’s Theory of Phase Transitions
Tipping the Scales
Non-equilibrium Phases of Matter
Soft Matter
Quantum Phases of Matter
Quantum Physics
Frozen yet Mobile—Superconductors, Bose–Einstein Condensates, and Strange Metals
Critical Symmetry
“Twistronics”—Graphene’s Magic Angle
Topological Phases of Matter
The Hall Effects
Topological Insulators and Topological Nanomaterials
Hunting for New Topological Materials—Can A.I. Help?
Entangled in More Ways Than One—Topological Quantum Computing
Topological Inspiration for Other Areas of Science
Condensed Matter and the Unification of Physics—The String-Net-Liquid Model
References
Emergence of Space
Introduction—Is Spacetime Doomed?
Einstein’s Space
Hints that Space Is Emergent
The Black-Hole Information Paradox
Quantum Entanglement
Space from Entanglement
The Universe as a Hologram—The AdS/CFT Duality
Why Entanglement?
How Entanglement Reproduces Space
Space as Error Correction
The Causal Wedge Paradox
Modeling Emergence with Qubits
Black Holes
Down the Wormhole—Resolving the Black-Hole Information Paradox
Island Rule
Complexity and Black Holes
Testing Emergence in the Lab: Black Hole Scrambling
Extending Duality
Going Beyond AdS/CFT
Loop Quantum Gravity
Causal Sets
Causal Dynamical Triangulations
References
Lateral Thinking—The Holographic Principle in Condensed Matter
Introduction
Dualing Theories
Nuclear Plasmas and Holography
Quantum Phases and Holography
The SYK Model—Creating Spacetime from Particles
References