Understanding Relativity: A Conceptual Journey Into Spacetime, Black Holes and Gravitational Waves (The Frontiers Collection)

This book bridges the huge gap between popular science and mathematical treatments of Einstein's theories. It explains special and general relativity, gravity, black holes, and gravitational waves, also presenting current ideas about dark matter and dark energy. The explanations are entirely non-mathematical, using many color pictures and clear concepts. In this way, the reader is led to a much deeper understanding than any popular science book can provide. The author has written this book for everyone who wants to go beyond superficial descriptions of relativity's remarkable phenomena, but is not equipped to read the professional literature and complicated math behind the theory. By providing a complete description in terms of concepts and pictures, the book answers many questions about why the theory works as it does. For example, it explains why and how momentum and pressure are related to gravity; why and how mass causes spacetime to curve and how curvature tells objects how to move; it also reveals the origin of the ring seen around the first ever image of a black hole. Not least, the reader will learn in detail how gravitational waves are produced and measured. Since their conception, the theories of relativity have appealed to the public's imagination. Thanks to this book, readers now have the opportunity to convert their fascination with the topic to a deep understanding. Title Copyright Epigraph Contents 1 Introduction 2 What is (the) Matter? 2.1 The Postulates of Special Relativity 2.2 Why We Are Waves 2.3 Wave Dynamics 3 On the Velocity of Massless Waves 3.1 Maxwell’s Speed of Light 3.2 Generic Speed of Light 3.3 Elasticity of the Vacuum 3.4 The Problem of the Ether 4 On the Velocity of Massive Waves 4.1 Wave Velocity 4.2 A Game with Rope and Springs 4.3 Consequence 1: You Cannot Go Faster Than Light 4.4 Consequence 2: The Relation Between Frequency and Wavelength Depends on the Mass 4.5 Consequence 3: Mass = Inertia 4.6 Consequence 4: Other Potential Differences Can Create “Mass” 4.7 Consequence 5: Mass Can Be Changed into Energy 4.8 Example: Photons in a Plasma 4.9 What These Consequences Say 4.10 Length Contraction and Time Dilation of Waves 4.11 Doppler Effect 4.12 Conclusions Regarding the Way We Perceive Distance in Spacetime 4.13 The Postulates of Special Relativity 4.14 About Higgs 5 The Relative, the Absolute, and the Paradoxical 5.1 Why Would a Distance in Space Care About Our Waves? 5.2 The Clash of the Observers 5.3 The Twin Paradox 5.4 Einstein’s Train 5.5 Extreme Energies and the Continuity of Spacetime 5.6 Conclusion 6 The Minkowski Metric 6.1 Defining the Metric 6.2 Origin of the Minkowski Metric 6.3 Coordinates in Minkowski Spacetime 6.4 Simultaneity 6.5 The Light Cone 6.6 Causality of Spacetime 6.7 Boosts 6.8 Interpretations of the Minkowski Metric 6.9 The Debate: Contracting Waves Versus Contracting Space 6.10 Bell’s Paradox of the Accelerating Spaceships 7 The Equivalence Principle 7.1 Two Different Meanings of “Mass” 7.2 Inertial Mass = Gravitational Mass 7.3 The Equivalence Principle 7.4 Can Gravity Bend a Light Beam? 7.5 How Does Mass Curve Spacetime? 7.6 Speculating About the Structure of the Vacuum 7.7 Inertia and How Spacetime Tells Mass How to Move 7.8 Perception or Reality? 7.9 Conclusion 8 The Curvature of Spacetime 8.1 What is a Curved Space? 8.2 Riemannian Manifolds 8.3 Making Curved Space from a Series of Flat Spaces 8.4 How to Curve Spacetime 8.5 Energy Conservation and Gravity 8.6 Geodesics 8.7 Tidal Forces 9 How Waves Change Shapes and Volumes 9.1 Changing Volumes and Changing Shapes 9.2 Waves as a Source of Gravitation 9.3 Conceptual Understanding of the Einstein Equation 9.4 Schwarzschild Metric 10 The Effects of Curvature 10.1 The GPS System 10.2 Gravitational Redshift and Doppler Effect 10.3 Geodesics Revisited 10.4 Mercury’s Orbit 10.5 Orbits of Light 10.6 Geodetic Precession 10.7 Frame Dragging 11 A Journey to the Centre of a Black Hole 11.1 Mass Limits and Collapsing Stars 11.2 Pinching the Light Cone 11.3 The Singularity 11.4 Hawking Radiation and the Unruh Effect 11.5 Thermodynamics and Entropy of a Black Hole 11.6 Rotating Black Holes 11.7 Charged Black Holes 12 Black Hole Phenomena 12.1 Gravitomagnetism and Jets 12.2 Analysing the Photos of the Black Hole in M87 12.3 The Black Hole in Our Own Galaxy 12.4 Black Hole Simulations in Analogue Physics 12.5 Wormholes and White Holes 13 Gravitational Waves 13.1 Symmetry in Spacetime 13.2 The Production and Propagation of Gravitational Waves 13.3 The Effect of Gravitational Waves 13.4 Observations and a Further Test of Einstein’s General Relativity 13.5 What Gravitational Waves Tell Us About the Nature of Spacetime 13.6 The Measurement Approach and Detectors 14 All that Matters in the Dark Universe 14.1 The Expanding Universe 14.2 Observations and Characteristics of Dark Matter 14.3 Dark Energy and the Cosmological Model 14.4 Observations and the Hubble Controversy 14.5 The Big Bang 15 Emergent Gravity and Conclusion 15.1 The Emergence of Spacetime and Gravity from Quantum States 15.2 Conclusions References Index