D O C . 3 2 9 F U N D A M E N T A L C O N C E P T S OF P H Y S I C S 495 ________________________ FUNDAMENTAL CONCEPTS OF PHYSICS AND THEIR MOST RECENT CHANGES !-------------------------------------------------------By Prof. Dr. Albert E inste in------------------------------------------------------- PRO FESSO R A LB ER T EDiSTEIN , one of the world’s greatest physicists and mathematicians, achieved universal fame through his theory of “Relativ- ity. laid down in a book by the like name which has been translated and discussed in all civilized languages. His startling announcement amounts in the aggregate to a re-interpretation of fundamental laws of nature, and has led to a revolution of scientific thinking since its general acceptance through the scholarly world. He won the Nobel prize for Physics in 1921 and in 1925 was awarded the equally coveted Copley Medal of the Royal Society of Great Britain. He is just fifty, and makes his home in Berlin. His contribution to this number of the Post-Dis- patch is a scholarly presentation of the problems now engaging the scientific minds. TRANSLATED FROM THE GERMAN BY REV. H. J. DE LAAK. S. J. (Copyright. 1928, by the Pulitzer Publishing Co., the St. Louis Post'Dispatch.) N o t w it h s t a n d in g the fact that our world, as the ob- ject of sense perception, re- veals to us directly but a vague Interdependence of events, and despite the fact that our actions appear to us as free, that is. not subject to any objective law. we. nevertheless, feel the need of interpreting events as neces- sary and fully under the control of law (causal). This need la assuredly a product of intellectual experience acquired In the course of evolution of culture. The primitive man. on the other hand, by analogy with his acts of will, seeks to refer all that hap- pens to the exercise of will on the part or Invisible spirits. The postulate of a strictly causal Interpre- tation of nature Is. therefore, In no way rooted In the human psyche, but Is the result of prolonged Intellectual adaptation. Confidence In the uninterrupted or- der of law In the course of natural phenomena la based, after all, upon only modest successes achieved by hu- man research In the Intellectual co- ordination of natural events . This confidence has, therefore, no absolute character. Even today many are In- fluenced by a feeling of opposition to the postulate or any unbroken order of laws. It Is not easy for us to look upon our arts of will as dependent upon strictly causal sequence and to waive our faith In the spontaneity of our actions. “ We can Indeed do as we like, hut we are compelled to like what we m ust do" m eans a bitter pill for proud man. N evertheless, who would deny th at In recent centuries learned men have swallowed this pill and digested It entirely? Despite our conviction that practical life cannot get along without the fiction of a free will, the doctrine of uninterrupted causality Is In no serious danger of a threat on the part of philosophic psychology. Especially, experiences concerning the action of internal se- cretions. of hypnosis, and of certain poisons upon psychic reactions, have had the effect of fairly well silencing opposition from th at quarter. Today faith In unbroken causality Is threatened precisely by those whose path It had Illum ined as their chier and unrestricted leader at the front, namely, by the representatives of physics. To understand this drift, which deserves the greatest Interest of all thinking men. we m ust take a [3] [1] [2]