Preface by W. Pauli Preface by A. Sommerfeld Bibliography Part 1. The Foundations of the Special Theory of Relativity Historical Background (Lorentz, Poincaré, Einstein) The Postulate of Relativity The Postulate of the Constancy of the Velocity of Light. Ritz's and Related Theories The Relativity of Simultaneity. Derivation of the Lorentz Transformation from the Two Postulates. Axiomatic Nature of the Lorentz Transformation Lorentz Contraction and Time Dilatation Einstein's Addition Theorem for Velocities and Its Application to Aberration and the Drag Coefficient. The Doppler Effect Part 2. Mathematical Tools The Four-Dimensional Space-Time World (Minkowski) More General Transformation Groups Tensor Calculus for Affine Transformations Geometrical Meaning of the Contravariant and Covariant Components of a Vector "Surface" and "Volume" Tensors. Four-Dimensional Volumes Dual Tensors Transition to Riemannian Geometry Parallel Displacement of a Vector Geodesic Lines Space Curvature Riemannian Coordinates and Their Applications The Special Cases of Euclidean Geometry and of Constant Curvature The Integral Theorems of Gauss and Stokes in a Four-Dimensional Riemannian Manifold Derivation of Invariant Differential Operations, Using Geodesic Components Affine Tensors and Free Vectors Reality Relations Infinitesimal Coordinate Transformations and Variational Theorems Part 3. Special Theory of Relativity. Further Elaborations Kinematics Four-Dimensional Representation of the Lorentz Transformation The Addition Theorem for Velocities Transformation Law for Acceleration. Hyperbolic Motion Electrodynamics Conservation of Charge. Four-Current Density Covariance of the Basic Equations of Electron Theory Ponderomotive Forces. Dynamics of the Electron Momentum and Energy of the Electromagnetic Field. Differential and Integral Forms of the Conservation Laws The Invariant Action Principle of Electrodynamics Applications to Special Cases Minkowski's Phenomenological Electrodynamics of Moving Bodies Electron-Theoretical Derivations Energy-Momentum Tensor and Ponderomotive Force in Phenomenological Electrodynamics. Joule Heat Applications of the Theory Mechanics and General Dynamics Equation of Motion. Momentum and Kinetic Energy Relativistic Mechanics on a Basis Independent of Electrodynamics Hamilton's Principle in Relativistic Mechanics Generalized Coordinates. Canonical Form of the Equations of Motion The Inertia of Energy General Dynamics Transformation of Energy and Momentum of a System in the Presence of External Forces Applications to Special Cases. Trouton and Noble's Experiments Hydrodynamics and Theory of Elasticity Thermodynamics and Statistical Mechanics Behaviour of the Thermodynamical Quantities Under a Lorentz Transformation The Principle of Least Action The Application of Relativity to Statistical Mechanics Special Cases Part 4. General Theory of Relativity Historical Review, Up to Einstein's Paper of 1916 General Formulation of the Principle of Equivalence. Connection Between Gravitation and Metric The Postulate of the General Covariance of the Physical Laws Simple Deductions from the Principle of Equivalence Influence of the Gravitational Field on Material Phenomena The Action Principles for Material Processes in the Presence of Gravitational Fields The Field Equations of Gravitation Derivation of the Gravitational Equations from a Variational Principle Comparison with Experiment Other Special, Rigorous, Solutions for the Statical Case Einstein's General Approximative Solution and Its Applications The Energy of the Gravitational Field Modifications of the Field Equations. Relativity of Inertia and the Space-Bounded Universe Part 5. Theories on the Nature of Charged Elementary Particles The Electron and the Special Theory of Relativity Mie's Theory Weyl's Theory Einstein's Theory General Remarks on the Present State of the Problem of Matter Supplementary Notes Author Index Subject Index