1 6 4 D O C . 1 5 6 O N B A S I C C O N C E P T S O F P H Y S I C S to this luminiferous ether that would be compatible with the observed facts & self- consistent. In that view, the luminiferous ether was a kind of matter, which, how- ever, had little in common with the “palpable & ponderable” matter dealt with by the rest of physics. Newton’s construction thus lost its original consistency. As the essential relationship between electricity & light became apparent through the research of Faraday & Maxwell, it soon became clear that one funda- mental concept of Newton’s theory could not be maintained in the face of observed facts this was the concept of forces acting instantaneously between elementary particles. A new fundamental concept was developed, that of fields. An electrically charged body was no longer supposed to act directly on another it was instead sur- rounded by a “field” that obeyed its own spatio-temporal laws & could even disen- gage from material bodies.[5] A field was understood as an energetic state of space, described by continuous functions, and initially was thought to be just as much part of physical reality as elementary particles. It soon appeared that this basic concept must be superordinate, in the sense that the electrons & protons could simply be considered as special locations of the field.[6] Electromagnetic mechanics arose as the attempt to derive mechanics from the field laws of electromagnetism. Thus, a new foundation of physics was created, which differed in principle from that of Newton in an extraordinary manner & even surpassed it in logical consis- tency. The theory of relativity that followed was nothing more than the consistent further extension of the field theory. It showed that simultaneity has no absolute character, that Euclidean geometry is not precisely valid. The positioning laws of material bodies were found to be a property of the gravitational field, whose law emerged from the theory.[7] Thus, the field theory shook the fundamental concepts of time, space, and mat- ter. But it left one of the pillars of the earlier structure of physics untouched: the hypothesis of causality. From the state of the world at a particular time, all its pre- vious & later states follow uniquely from the laws of nature. Today, however, serious doubts have arisen concerning causality as understood in this theory. This is not the fault of an addiction to novelty on the part of scien- tists, but rather it stems from the force of the empirical facts that would appear not to be compatible with a strictly causal theory. It would seem today that the field concept as the final structure of reality is not sufficient to describe correctly the phenomena of radiation & atomic structure. We have arrived at a complex of ques- tions with which the current generation of physicists struggles with an enormous expenditure of mental power.— [p. 5]