## Space, Time and Gravitation: An Outline of the General Relativity Theory |

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absolute significance acceleration aether appears arbitrary atom centrifugal force coordinates corresponding curvature curved defined definite deflection described determine direction displacement distance drē dsē earth eclipse Einstein's law electrical energy equations Euclidean geometry Euclidean space exist experiment experimental field of force formula four-dimensional world geodesics give gravitational field hurdles inertia interval interval-length kind of space-time law of gravitation length light-wave mass material mathematical matter meaning measures mechanics mesh-system Michelson-Morley experiment momentum moving natural geometry natural tracks Newton's law Newtonian non-Euclidean observer orbit ordinary particle partitions phenomena Phys physicist physics planet point-events possible principle of relativity properties quantity radius recognised region relations relativity theory rigid scale rotation round scales and clocks seems space speed stars straight line supposed surface t₂ terrestrial theory of relativity thing three-dimensional three-dimensional space tion uniform motion values velocity of light W. K. CLIFFORD μν

### Popular passages

Page 93 - I do not know what I may appear to the world, but to myself I seem to have been only like a boy playing on the sea-shore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.

Page 115 - For in and out, above, about, below, 'Tis nothing but a Magic Shadow-show, Play'd in a Box whose Candle is the Sun, Round which we Phantom Figures come and go.

Page 14 - Pure mathematics consists entirely of such asseverations as that, if such and such a proposition is true of anything, then such and such another proposition is true of that thing. It is essential not to discuss whether the first proposition is really true, and not to mention what the anything is of which it is supposed to be true.

Page 77 - The hypothesis that space is not homaloidal [flat], and again that its geometrical character may change with the time, may or may not be destined to play a great part in the physics of the future; yet we cannot refuse to consider them as possible explanations of physical phenomena, because they may be opposed to the popular dogmatic belief in the universality of certain geometrical axioms — a belief which has risen from centuries of indiscriminating worship of the genius of Euclid.

Page 197 - The relativity theory of physics reduces everything to relations ; that is to say, it is structure, not material, which counts. The structure cannot be built up without material ; but the nature of the material is of no importance.

Page 45 - For instance, here is a portrait of a man at eight years old, another at fifteen, another at seventeen, another at twenty-three, and so on. All these are evidently sections, as it were, Three-Dimensional representations of his Four-Dimensioned being, which is a fixed and unalterable thing.

Page 113 - It is thus necessary to have rather bright stars near the sun, which will not be lost in the glare of the corona. Further the displacements of these stars can only be measured relatively to other stars, preferably more distant from the sun and less displaced; we need therefore a reasonable number of outer bright stars to serve as reference points. In a superstitious age a natural philosopher wishing to perform an important experiment would consult an astrologer to ascertain an auspicious moment for...

Page 93 - I don't know what I may seem to the world ; but as to myself, I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of Truth lay all undiscovered before me.

Page 200 - It is even possible that laws which have not their origin in the mind may be irrational, and we can never succeed in formulating them.