On the nature of X-rays

Abstract

Einstein’s statistical-thermodynamic calculations of the random variations of the radiation density constitute the ground upon which the light quantum hypothesis was originally based. According to these calculations such a variation of the radiation energy prevails—superposed above the fluctuations caused by the interferences calculated according to the classical theory—as if the radiation consisted of mutually independently mobile quanta hv of energy. According to Einstein, Maxwell’s theory correctly renders mean time values, which alone have been directly observable, as proved by the complete agreement between theory and experiment in optics; but Maxwell’s theory leads to laws respecting the thermic properties of radiation which are incompatible with the entropy-probability relation. After the wave-mechanical theory of de Broglie and Schrödinger had been generally accepted, the idea concerning the statistical character of the wave-field—already presented by Einstein in 1905—has, of course, been taken up again by Born in a more general way. As is well known, Bohr and Heisenberg have tried to conquer the difficulties to which the radiation theory has led by a radical change in our conception of energy.