72 CURRENT TOPICS. [J. F. I.

To Albert Einstein on his Fiftieth Birthday. PROF. M. YON LAUE. (Naturwissensch., March I5, I929.) "Physics in I929 is different from the same science in 19o4 and immensely richer. The history of this science will place over this epoch not a single name, nor even two or three names alone. I t is, however, assured that the name of Einstein will be one of the first to be there in- scribed.

"We are embarrassed if we must say which of his ideas has most continuously influenced investigation. To-day we cannot separate from Physics the 19o5 Theory of Relativity which, by rejecting the ancient prejudice for 'absolute' time, solved at a stroke the century-old riddles of the ether and of the electro- dynamics and optics of moving bodies. Nor can we to-day conceive of Thermodynamics without the quantum theory of specific heat nor of atomic theory without the 'h~ relation.' All these we owe to the work of Einstein as a young man.

"For these reasons physicists salute Albert Einstein as a pioneer of the first order. And shall physicists alone do this? Shall not also chemists for whom the conception of the absorption of radiation by quanta has furnished a new basis for photochemistry? And astronomers for whom he explained the puzzling motion of the perihelium of Mercury and whom he incited to discover the deviation of light by the sun and led to investigate with care the shifting of spectral lines? And not also mathematicians to whom he showed how Nature makes real non-euclidean geometry and to whom he has pointed out recently a road to a new generalization of this geometry? And perhaps even professional philosophers will join in the acclaim for, no matter what value they may attach to the Theory of Relativity, they must recognize the service of one who in an age far removed from idealism has directed the attention of wide circles to the importance of the philosophical criticism of knowledge."

G. F. S.