Book Read Free

A Stubbornly Persistent Illusion

Page 46

by Stephen Hawking


  in tube, electricity discharge, 312–313

  Gaussian co-ordinates, 195–197, 203–205

  Gell-Mann, Murray, 283

  general laws of nature, general co-variance for the equations expressing, 50–53

  generally covariant equations, mathematical aids to formulation of, 55–77, 421

  antisymmetrical extension of a six-vector, 73

  contravariant and covariant four-vectors, 56–58

  curl of a contravariant vector, 73

  divergence

  of a contravariant vector, 72–73

  of a mixed tensor of the second rank, 74–75

  of a six-vector, 73–74

  fundamental tensor (uv) (insert correct symbols, please), 62–66, 71–72

  geodetic line, equation of, 66–68

  multiplication of tensors, 60–62

  particle, motion of, 66–68

  Riemann-Christoffel tensor, 75–77

  tensors

  formation by differentiation, 68–71

  of second and higher ranks, 58–60

  general theory of relativity. See relativity, general theory of

  geodetic line

  equation of, 66–68

  movement in gravitational field, 78

  geometrical invariant, 271–272

  geometrical propositions, physical meaning of, 129–131

  geometry

  bodies at rest, 47

  experience and, 249–262

  as intermediary between physical sciences and math, 247–248

  physical standpoint, 386

  space and time, 386

  globe, unbounded continuum, 258–261

  gravitation

  field equations, deducing from laws of conservation, 104

  mechanics and, 36–37

  Newton’s law of, 166, 190, 237, 391, 400, 411

  gravitational field, 177–178, 237

  absence of matter, field equations for, 78–80

  acceleration, imparting, 49, 389

  bending of light rays in, 43–45

  centrifugal force, 189–191

  clocks and, 42–43

  conservation in the general case, laws of, 84–85

  describing, 431–432

  electricity, combined equations with, 433

  electromagnetic field and, 78–79, 422–423

  ether and, 245

  field-components, expression for, 77–78

  field equations of gravitation, general form of, 82–84

  Hamiltonian function, 80–82

  law of, 372

  light, deflection by, 228–229

  lines of force, 286

  material point, equations of motion of, 77–78

  momentum and energy for matter, laws of, 85–86

  momentum and energy, laws of, 80–82

  Newton’s theory, divergence from, 400

  pure, 375

  ray of light, transmitting curvilinearly, 185–186

  role in structure of elementary particles of matter, 117–124

  cosmological question, 122–124

  defects in present (1919) view, 117–119

  scalars, field equations freed of, 119–122

  separate existence (Hamilton’s Principle), 101

  space and time absent, 187–188

  gravitational lensing, 126

  gravitational mass, 181, 368–369

  gravitation, solution of problem of, 206–209

  Grommer, J., 109

  H

  Hamilton’s Principle

  gravitational field, theory of, 80–82

  invariants, theory of, conditioning properties of field equations of gravities, 101–104

  principle of variation and field–equations of gravitation and matter, 99–100

  separate existence of gravitational field, 101

  Hawkings, Stephen, ix–xi

  heat

  phenomena, 393, 394, 413, 414

  radiation investigations of Planck, 356–359

  wires between charged plates, 304

  Heisenberg, Werner, 425

  Hertz, G., 428

  Hertz, Heinrich, 239–240, 416, 439–440. See also Maxwell-Hertz equations

  heuristic value of theory of relativity, 162

  Hilbert, D.

  defects in theory, 117

  variation, theory of relativity from, 99

  homogeneity of space, 276

  Hubble, Edwin, 3, 126

  Huyghen’s principle, 43–45, 97

  hydrodynamics, 347, 413

  hydrogen atom, 304–305

  I

  indivisible steps, change, 301–306, 324

  induced currents, 295–299

  induction, 297, 405

  inertia, 351

  of a body, dependence on energy content, 32–34

  β-rays, 168

  constant controlling, 399

  co-ordinates, system of, 335

  disk, centrifugal force acting on, 189–190

  law of, 137, 388, 411

  law of constancy of light velocity, 419

  light and, 387

  Mach’s theory, 351–352, 367, 438

  magnetic field and, 417

  material point of mass, 111

  radiation conveying between emitting and absorbing bodies, 34

  inertial mass, 181

  classical mechanics problem, 420

  constant of accelerated body, 178

  energy increasing, 368–369

  equivalence, principle of, 389

  gravitational, equality with, 179–182

  gravitation of energy, 37–40

  Infield, Leopold. See The Evolution of Physics

  infinity, spatial, 105–106

  inner multiplications of tensors, 61–62

  intervals

  Cartesian co-ordinate system, 268–269

  rate of, 254

  rigid body, 267–268

  two points on rigid body, 267

  invariants, theory of, 101–104

  isotropy of space, 276

  J

  Jacobi’s theorem, 272

  Jupiter, 45

  K

  Kaluza, Theodor, 423

  kinematics

  electrodynamics of moving bodies, 5–18

  as laws regarding measuring bodies and clocks, 47

  length and time, relativity of, 7–9

  moving rigid bodies and moving clocks, equations from, 14–16

  simultaneity, definition of, 5–7

  special theory of relativity and, 398, 400

  velocities, composition of, 16–18

  kinetic energy, 353

  of the body, 166

  mass, material point of, 163–164

  kinetic theory, gas particles, 357, 358, 414

  Kirchhoff, Gustav, 356

  L

  Laser Interferometer Gravitational wave Observatory (LIGO), 248

  Laser Interfoerometer Space Antenna (LISA), 248

  later events, 265

  law of conservation of momentum and of energy for the gravitational field, 81–82

  law of constancy of light velocity, 419

  law of constancy of velocities, 142

  law of inertia, 137, 388, 411

  law of motion, 168–169, 352, 375, 411

  law of pressure, 453

  law of the constancy of the velocity of light, 144

  law of the parallelogram of velocities, 17

  law of the transmission of light in vacuo, 155–156

  laws of conservation. See conservation

  length

  distance, relativity of the conception of, 151–152

  of interval, 268

  measurements of, 132

  of moving rods, 8–9, 14

  and time, relativity of, 7–9

  wave listed by color, 314–315

  LeVerrier, Urbain, 98

  light

  aberration of, 453

  bending, 2

  clock, using as, 263–264

  comp
act fields from which can’t escape, 126

  curving by action of gravitational fields, 400

  deflection by gravitational field, 228–229

  Ether, theory of, 238

  gravitation and propagation of

  bending of light rays in gravitational field, 43–45

  gravitation of energy, 37–40

  physical nature of gravitational field, hypothesis of, 35–37

  time and velocity of light in gravitational field, 40–43

  homogeneous, extracting electrons from metal, 307–308

  law of constancy of velocity, 419

  law of the constancy of the velocity of, 144

  in liquid, traveling with particular velocity, 160–161

  measuring height of clouds, 133

  motion of material points, 415

  particle properties of, 284

  phenomenological physics, 413–414

  quanta, 306–312

  radiation, 312

  ray

  curvature of, 97

  transformation of the energy of, 23–26

  velocity of, 8, 11–13

  as shower of photons, 309–310

  source of, inertia and, 387

  spectra, 312–316

  speed of, 1, 2, 5, 366–367, 386

  stars, lines of light from, 96

  transmitting rectilinearly, 185–186

  in vacuo, constancy of, 398

  wave-motion of, 347, 438

  lightning strike, simultaneity of, 145–146, 148

  LIGO (Laser Interferometer Gravitational wave Observatory), 248

  lines of force

  of the gravitational field, 286

  induction phenomena, 297

  magnetic field, 288–289

  metal plates, 303–304

  line, straight, 130

  movement

  not subject to external forces, 77–78

  relative to two different points, 138

  properties of, 268

  liquid, light traveling through, 160–161

  LISA (Laser Interfoerometer Space Antenna), 248

  longitudinal mass, 29

  Lorentz contraction, 51

  Lorentz, Hendrick A., 144, 170. See also Maxwell-Lorentz theory

  covariant law for scalar field, 374

  electrodynamic theory, 161, 240

  empty space as seat of field, 416–417

  field-theory of gravitation and, 373–374

  stationary charges, 1

  theory of matter, 354–356

  variation, theory of relativity from, 99

  Lorentz transformation, 26–27, 153–156

  addition of velocities, 160

  conditions, 198–199

  demand, 387–388

  Galileo’s versus, 263

  limiting velocity, 157–158

  simple derivation of, 218–222

  space-time variables, replacing, 203

  velocities, 153–154

  Luminiferous Ether, 235, 238

  M

  Mach, Ernst, 47, 184, 348, 414

  inertia, 351–352, 367, 438

  mean acceleration, 243–244

  magnetic field, 177

  asymmetries, 4

  current acting upon magnetic pole, 287–288

  electrical current, 287, 294

  inertia and, 417

  lines of force, 288–289

  masses, 415

  in motion, 18–23

  positive force, 288

  magnetomotive forces, 21

  maps, distances and, 300

  marble slab rods example, 192–194

  mass

  conservation of, 164, 392

  defined, 393–394

  densities, 256–257

  discontinuous nature of, 302

  electric, introduction of, 350

  and energy, equivalence of, 392–393, 394, 453–455

  hydrogen atom, 304–305

  inertia, 111

  inertial and gravitational, equality of, 179–182

  kinetic energy of a material point of, 163

  magnetic field, 415

  negative electrical, 168

  reciprocal action between, 256

  material particle. See particles

  material phenomena, 86–98

  free space, Maxwell’s electromagnetic field equations for, 88–91

  frictionless adiabatic fluid, Euler’s equations for, 87–88

  Newton’s theory as a first approximation, 92–94

  rods and clocks, behavior in static gravitational field, 94–96

  material point

  describing, 410–411

  equations of motion of, 77–78

  forces on, 412

  mathematics

  antisymmetrical extension of a six-vector, 73

  contravariant and covariant four-vectors, 56–58

  curl of a contravariant vector, 73

  divergence

  of a contravariant vector, 72–73

  of a mixed tensor of the second rank, 74–75

  of a six-vector, 73–74

  education in autobiographical notes, 344–346

  fundamental tensor (uv) (insert correct symbols, please), 62–66, 71–72

  geodetic line, equation of, 66–68

  multiplication of tensors, 60–62

  particle, motion of, 66–68

  physics versus, 246

  real things, measuring, 249–253

  Riemann-Christoffel tensor, 75–77

  tensors

  formation by differentiation, 68–71

  of second and higher ranks, 58–60

  matter

  absence, field equations for, 78–80

  density defining energy-tensor, 93–94

  elementary particles, gravitational field and structure of, 119–122

  elementary quanta, 301–306

  Lorentz’s theory, 354–356

  molecular structure of, 435

  uniform distribution in spatially finite universe, 111–115

  waves of, 316–323

  Maxwell-Hertz equations

  for currents, 330

  electromagnetic waves, 440

  for empty space, 32

  mechanics as basis of physics, 347

  transformation, 18–23

  Maxwell, James Clerk

  asymmetries in moving bodies, 4

  electric field theory, 415–416

  electricity and magnetism theory, 1, 338, 367

  electrodynamics, 187

  electromagnetic action at distance, 166, 350, 415–416, 439–440

  electromagnetic field theory

  autobiographical notes, 353–354

  as foundation of electron theory of Lorentz, 281, 441–442

  fundamental equations of electrodynamics, 164–165

  speed of light and, 5

  empty space, equations of, 379–380

  fields as fundamental variables, 353–354

  free space, electromagnetic field equations for, 88–91

  Maxwell-Lorentz theory

  body moving uniformly, 169

  electron, theory of, 119

  ether and, 239

  experimental arguments in favor of, 167–168

  Maxwell-Poynting expressions, 91

  mean acceleration, 243–244

  The Meaning of Relativity (Einstein), 263–282

  measurable distance between two points, 271

  measurement

  distance, 132

  of events, 386

  real things with mathematics, 249–253

  measuring rods. See rods

  mechanics

  as basis of physics, 351–353

  electricity and, 414–415

  force laws and, 411

  gravitation and, 36–37

  inertial mass problem, 420

  natural phenomena, insufficiency to describe, 139

  observable fact of experience, 48

  physics and reality, 406–414

  phy
sics, inadequacy as basis of, 349–351

  potential energy as function of configuration, 412

  relativity principle, 139

  space and time, 135–136

  special theory of relativity, 46

  unsatisfactory aspects of, 183–184

  Mercury

  ellipses of planetary orbits, 400

  mass density, 256

  perihelion motion, 226–227, 391

  rotation, 98

  metal plates

  electrons, extracting, 307–308

  lines of force, 303–304

  method of statistics, 325–326

  quantum physics, 327–328

  metrical character (curvature), four-dimensional space-time continuum, 111–112, 116

  Michelson, Albert, 169–170, 235

  Mie, G., 117, 119

  Milky Way

  distribution of stars, 256–257

  mean density, 256

  Millikan, Robert, 428

  Minkowski, Peter, 89

  four-dimensional space, 171–173, 223–224, 365

  objects to which motion cannot be applied, 242

  space-time continuum as Euclidean continuum, 198–199

  mixed multiplications of tensors, 61–62

  mixed tensors, 59

  molecules

  elementary quanta of matter, 301–302

  matter, structure of, 435

  momentum

  conservation of, 366, 453

  gravitational field, theory of, 80–82, 85–86

  money, change and, 300–301

  Morley, Edward, 170

  Ether, 235

  speed of light, 1

  motion. See also kinematics; wave

  clocks and, 204

  coordinate systems in any state of, 443

  corpuscles, 320

  describing, need for second body and, 397

  distant masses, 48

  law of, 2, 168–169, 178, 263, 346, 352, 355, 375, 411

  magnetic field creating electricity, 294

  material particle, equations of, 277

  of material point, 77–78, 93–94, 201–202, 415

  neutral particle, 433

  Newton’s law of, 2, 178, 263, 346, 355

  nonuniform, 176

  rectilinear and uniform, body in, 387

  retardation, 182

  rigid bodies and moving clocks, equations from, 14–16

  tensors, equations of, 278–279

  theory of relativity and, 385

  uniform acceleration, 420

  uniform rectilinear, 185

  motion of uniform translation. See relativity, special theory of; special theory of relativity

  movement

  chest against gravitational field, 179–182

  straight line, 138

  moving bodies

  electrodynamical part

  convection-currents, transformation of Maxwell-Hertz equation with, 26–31

  light rays, transformation of the energy of, 23–26

  magnetic field in motion, 18–23

  negative electrical masses, 168

  perfect reflectors, theory of the pressure of radiation exerted on, 23–26

  kinematical part

  co-ordinates and times, converting from stationary system, 9–14

 

‹ Prev