Page:Eddington A. Space Time and Gravitation. 1920.djvu/234

218 * Perihelia of planets, motions of, 123
 * Permanence of matter, 196
 * Permanent identity, 40, 193
 * Permanent perceptual world, 141, 198
 * Poincaré, 9
 * Point-event, 45, 186
 * Potentials, 80; Galilean values, 83
 * Potentials, electromagnetic, 172
 * Principe, eclipse expedition to, 114
 * Principle of Equivalence, 76, 131, 212
 * Principle of Least Action, 149, 178
 * Principle of Relativity (restricted), 20
 * Probability, a pure number, 178
 * Projectile, Jules Verne's, 65
 * Propagation of Gravitation, 94, 147
 * Proper-length, 11
 * Proper-time, 71
 * Pucker in space-time, 85


 * Quanta, 60, 177, 182, 200


 * Radiation-pressure, 110
 * Real world of physics, 37, 181
 * Receding velocities of B-type stars, 135; of spiral nebulae, 161
 * Reflection by moving mirror, 22
 * Refracting medium equivalent to gravitational field, 109
 * Refraction of light in corona, 121
 * Relativity of force, 43, 76; of length and duration, 34; of motion, 38; of rotation, 152, 155; of size, 33
 * Relativity, Newtonian, 40; restricted Principle of, 20; standpoint of, 28
 * Repulsion of light proceeding radially, 102, 108
 * Retardation of time, 24, 55; in centrifugal field, 129; in spherical world, 160
 * Ricci, 89
 * Riemann, 2, 89, 167
 * Riemann-Christoffel tensor, 89
 * Riemannian, or non-Euclidean, geometry, 6, 73, 84, 90
 * Rigid scale, definition of, 3
 * Rotation, absolute, 152, 164, 194
 * Rotation of a continuous ring, 194
 * Russell, 14, 197


 * St John, 130
 * Semi-Euclidean geometry, 47
 * Simultaneity, 12, 51
 * de Sitter, 134, 159, 179
 * Sobral, eclipse expedition to, 117
 * Space, conventional, 9; kinds of, 81; meaning of, 3, 8, 15; relativity of, 34
 * Space-like intervals, 60, 187
 * Space-time, 45; due to Minkowski, 212; partitions of, 54
 * Spherical space-time, 159
 * Standard metre, comparison with, 168
 * Stresses in continuous matter, 193
 * Structure opposed to content, 197, 200
 * Structure, geodesic, absolute character of, 155, 164; acceleration of, 195; behaviour at infinity, 157
 * Super-observer, Newton's, 68
 * Synthesis of appearances, 31, 182


 * Tensors, 89, 189
 * Thomson, J. J., 61
 * Time, absolute, 163; depends on observer's track, 38, 57; for moving observer, 24; imaginary, 48; measurement of, 13; past and future, 51; "standing still," 26, 160
 * Time-like intervals, 60, 187
 * Tracks, natural, 70


 * Vacuum, defined by law of gravitation, 190
 * Vector, non-integrable on Weyl's theory, 174
 * Velocity, addition-law, 59; definition of, 193; static character, 194
 * Velocity of gravitation, 94, 147
 * Velocity of light, importance of, 60; in gravitational field, 108; system moving with, 26, 56


 * Warping of space, 8, 126
 * Wave-front, slewing of, 108
 * Weight, of light, 107, 111; of radio-active energy, 111; proportional to inertia, 137; vanishes inside free projectile, 65
 * Weyl, 174
 * World, 186, 187
 * World-line, 87