Confronting the Enigma of Time

Description

In Newton's classical mechanics, time played the role of a monotonically increasing evolution parameter. Einstein rejected the Newtonian concept and instead identified time as the fourth coordinate of a space-time four-vector. Today, scientists are considering different concepts of time as a means of resolving incompatibilities between relativity and quantum mechanics. Some view time as an emergent property of a system rather than a fundamental property, while others consider two temporal variables. The purpose of this book is to examine the role of time in modern physics so that the reader gains an increased awareness of time and its place in our understanding of nature. Contents Preface About the Author Chapter 1 Introduction to the Enigma of Time Part 1 Newtonian Time Chapter 2 Time from Prehistory to the Ancient Greeks 2.1 The Stone Age 2.2 The Urban Revolution 2.3 The Ancient Greek View of Time The Ionian influence The Eleatic view The atomist view Plato Aristotle 2.4 The Hellenistic Period Endnotes Chapter 3 Time from Ptolemy to Kepler 3.1 Ptolemaic System or Copernican System? 3.2 Galileo Galilei Galileo’s pendulum clock 3.3 Normal Science and Scientific Paradigms Falsification Endnote Chapter 4 Newton and Maxwell 4.1 Newtonian Mechanics 4.2 Causality 4.3 Classical Electrodynamics 4.4 Wave Motion and the Electromagnetic Spectrum Endnote Part 2 Einsteinian Time Chapter 5 Einstein’s Special Relativity 5.1 Galileo’s Ship 5.2 Galilean Relativity 5.3 Newtonian Relativity Invariance Maxwell’s equations The Michelson–Morley experiment 5.4 Synchronizing Travel Travel by rail 5.5 Einsteinian Relativity Addition of relativistic velocities Relativistic mass Endnote Chapter 6 Paradoxes of Special Relativity 6.1 Spacetime Diagrams 6.2 Pole-in-the-Barn Paradox 6.3 The Twin Paradox 6.4 The Grandfather Paradox 6.5 The Meaning of ‘Now’ Endnote Chapter 7 Gravity and Action at a Distance 7.1 Newtonian Gravity 7.2 Action at a Distance 7.3 Action at a Distance on the Subatomic Level 7.4 Relationalism Newton’s bucket experiment The Foucault pendulum Mach’s principle Relationalism and emergent properties Endnote Chapter 8 General Relativity 8.1 Deflection of Light Rays 8.2 Frames of Reference and the Elevator Gedanken Experiment 8.3 Einstein’s Principle of Equivalence 8.4 Einstein’s General Theory of Relativity 8.5 Early Tests of General Relativity The perihelion of Mercury Gravitational redshift and blueshift 8.6 Gravitational Waves Endnotes Part 3 Cosmology and the Inflationary Universe Chapter 9 Introduction to Modern Cosmology 9.1 Einstein’s Cosmology 9.2 Cosmological Models Before 1929 9.3 Early Evidence of an Expanding Universe Cosmological redshift 9.4 Hubble’s Law 9.5 Lemaître’s Cosmogony Endnote Chapter 10 Evidence for the Expanding Universe 10.1 Cosmic Distance Ladder Stellar parallax Cepheid variable stars Supernovae Cosmic distance ladder 10.2 Expansion of the Universe What is expanding? Does the speed of recession have a limit? 10.3 Cosmic Microwave Background Radiation Discrepancy in the Hubble constant Endnotes Chapter 11 Physics of the Subatomic Scale 11.1 Transition from Classical Physics to Quantum Physics Black body radiation 11.2 The Uncertainty Principle The energy–time uncertainty relation 11.3 Complementarity and Wave–Particle Duality 11.4 Born’s Probabilistic View 11.5 Interpretations of Quantum Theory Schroedinger’s cat Endnotes Chapter 12 Prelude to the Big Bang 12.1 Fundamental Interactions and Particle Classification 12.2 Atomism and Quarks Atoms and quantum numbers The quark model 12.3 Relativistic Quantum Theory 12.4 Standard Model of Particle Physics Particles or fields? Anomalies of the Standard Model of Particle Physics Endnotes Chapter 13 The Inflationary Universe 13.1 The Big Bang — The Moment of Creation 13.2 The Standard Model of Cosmology 13.3 Cosmological Model Parameters Estimating the size of the universe Hubble flow and cosmic time Estimating the amount of matter in the universe 13.4 Dark Matter 13.5 Dark Energy and Inflation 13.6 The Inflationary Universe 13.7 The ΛCDM Model The cosmological constant problem Endnotes Part 4 The Future of Time Chapter 14 Time’s Arrow 14.1 Entropy and Thermodynamics Thermodynamic systems and states Entropy The laws of thermodynamics 14.2 Entropy and Statistical Mechanics 14.3 Time’s Arrow The direction of time’s arrow Lemaître’s frame and the moment NOW Is time’s arrow real? Endnotes Chapter 15 Time: Death or Rebirth? 15.1 Grand Unified Theory and a Theory of Everything The Core Theory 15.2 The Many-Worlds Interpretation Revisited 15.3 Quantum Gravity The problem of time 15.4 The Block Universe and the Rebirth of Time Endnotes Chapter 16 Historical Time 16.1 Temporal Hypotheses 16.2 Temporal Measurements Thought experiment for measuring a particle worldline The evolution parameter clock 16.3 Alternative Interpretations 16.4 Experimental Tests Endnotes Chapter 17 Epilogue — Resolving the Enigma of Time Dates of Selected Characters References Index