James Jeans quotes
A second conspicuous landmark... is the enunciation of the fundamental law of radioactive disintegration by Rutherford and Soddy in 1903. This law was in no sense a consequence or development of Planck's theories; indeed fourteen years were to elapse before any connection was noticed between the two. The new law asserted that the atoms of radioactive substances broke up spontaneously, and not because of any particular conditions or special happenings. This seemed to involve an even more startling break with classical theory than the new laws of Planck; radioactive break-up appeared to be an effect without a cause, and suggested that the ultimate laws of nature were not even causal.
James Jeans
Minkowski... supposed that this fourth dimension of time was not detached from and independent of the three dimensions of space. He introduced a new four-dimensional space to which ordinary space contributed three dimensions, and time one; we may call it 'space-time'.... The succession of positions which a particle occupied in ordinary space at a succession of instants of time would be represented by a line in space-time; this he called the 'world-line' of the particle.... Newton's absolute space and absolute time fell out of science, and they carried much with them in their fall. First to go was the concept of simultaneity.... It now became necessary to find a way of treating gravitation which should not involve simultaneity. Einstein found through the medium of his 'Principle of Equivalence'.
James Jeans
In every previous application of the quantum law, Planck's law, that the energy is h [Planck's constant] times the frequency, had been used to deduce the energy of a quantum when the frequency of the radiation was already known. In the present case the formula was used the other way; the energy of the emitted photon was known to begin with, and the formula was utilized to deduce its frequency. The frequencies calculated in this way are found to agree completely and exactly with those of the spectrum of hydrogen.
James Jeans
When two hypotheses are possible, we provisionally choose that which our minds adjudge to be simpler, on the supposition that this is the more likely to lead in the direction of truth. It includes as a special case the principle of Occam's razor-entia non multiplicana praeter necessitatem.
James Jeans
In 1925 Heisenberg made a new attempt, on entirely novel lines, to obtain an explanation of atomic spectra. Working in collaboration with Bohr, he had come to the conclusion that the imperfections of Bohr's theory had been a consequence of assuming too simple a model for the atom. For Bohr had not only assumed that the atom consisted of particles moving through space and time, but also that the particles inside atoms were of the same kind as the electrons outside atoms.
James Jeans
...when the experiment was attempted by Michelson and Morley it failed, thus showing that space and time assumed in the picture were not true to the facts of nature. ...the pattern of events was the same whether the world stood at rest in the supposed ether, or had an ether wind blowing through it at a million miles an hour. It began to look as though the supposed ether was not very important in the scheme of things... and so might as well be abandoned. But if the bell-rope is to be discarded, what is to ring the bell?
James Jeans
if a shower of electrons is shot on to a zinc sulfide screen, a number of flashes are produced - one for each electron - and we may picture the electrons as bullet-like projectiles hitting a target. But if the same shower is made to pass near a suspended magnet, this is found to be deflected as the electrons go by. The electrons may now be pictured as octopus-like structures with tentacles or 'tubes of force' sticking out from it in every direction.
James Jeans
The laws which governed the spontaneous jumps of the kangaroos were shown to be of the simplest; out of any number of kangaroos a certain proportion always jumped within a specified time, and nothing seemed to be able to change this number. Also, before the jumps took place, there was nothing in the world of phenomena to distinguish those kangaroos that were about to jump from those that were not... to help fill the quota demanded by the statistical law. As discontinuity marched into the world of phenomena through one door, causality walked out through another.
James Jeans
The complete closed world consists of three parts-substratum, phenomenal world, and observer. By our experiments we drag up activities from the substratum into the phenomenal world of space and time, but there is no clear line of demarcation between subject and object, and by performing observations on the world, we alter it, much as a fisherman dragging up fish from the depths of the seas disturbs the waters and also damages the fish.
James Jeans
The classical mechanics had envisaged the world constructed of matter and radiation, the matter consisting of atoms and the radiation of waves. Planck's theory called for an atomicity of radiation similar to that which was so well established for matter. It supposed that radiation was not discharged from matter in a steady stream like water from a hose, but rather like lead from a machine-gun; it came off in separate chunks which Planck called quanta. This... carried tremendous philosophical consequences.
James Jeans
This fallacious result is not... a peculiarity of classical mechanics; it is given also by a very wide class of possible systems of mechanics. This being so, no minor modification of the classical mechanics can possibly put things right. Something far more drastic is needed; we are called upon to surrender either the [1] continuity or the [2] causality of classical mechanics, or else the possibility of [3] representing changes by motions in time and space.
James Jeans
It can hardly be a matter for surprise that our race has not succeeded in solving any large part of its most difficult problems in the first millionth part of its existence. Perhaps life would be a duller affair if it had. For to many it is not knowledge but the quest for knowledge that gives the greater interest to thought - to travel hopefully is better than to arrive.
James Jeans
A theoretical investigation which Einstein published in 1917 provides a third conspicuous landmark. It connected up he two great landmarks already mentioned by showing that the disintegration of radioactive substances is governed by the same laws as the jumps of the kangaroo electrons in the theory of Bohr. In fact radioactive atoms were now seen merely to contain a special breed of kangaroos, much more energetic and ferocious than any that had hitherto been encountered.
James Jeans
