2 9 8 D O C . 3 1 3 O N C U R R E N T S T A T E O F F I E L D T H E O R Y 313. “On the Current State of the Field Theory” [Einstein 1929j] Dated between 14 November 1928 and 10 January 1929[1] Published 1929 In: Emil Honegger, ed.: Festschrift zum 70. Geburtstag von Prof. Dr. A. Stodola. Zurich and Leipzig: Füssli,1929, pp. 126–132.[2] A brief treatment of the goals and content of field theories. A sketch of the more recent attempts at a field theory in the area of general relativity (continuum with a Riemannian metric and distant parallelism). The field theory, which in my opinion is the deepest conception in theoretical physics since its foundation by Newton, was the brainchild of Faraday. How simple this idea seems a posteriori and yet how sublime it is! Instead of thinking, “An elec- tric particle e 1 acts on a second particle e 2 across space and exerts a force on it, which can cause it to move,” Faraday thought as follows: “An electric particle causes a modification in the state of the immediately surrounding space (i.e., an electric field) through its very existence. The spatial distribution and the time evo- lution of such a field are determined by laws that are properties of space. Owing to these laws, the field that surrounds particle e 1 extends to particle e 2 and acts there on that particle.” Based on these ideas, Maxwell’s wonderful laws of the electro- magnetic field were soon formulated. Hertz demonstrated unequivocally that this field theory should take precedence over Newton’s action at a distance, and shortly thereafter, H. A. Lorentz showed that this field is located everywhere in empty space, even in the interior of matter indeed, that the elementary constituents of matter—at least with respect to electromagnetism—are none other than the source points of the electric field. This was the state of our knowledge around the turn of the century. Before I continue considering the development of field theory, I should like to interpose a brief remark on the goals and tendencies of theoretical research in gen- eral. This theory has two aspirations: 1. To encompass as many phenomena as possible, and their interconnections (completeness) [3] 2. To accomplish this by making use of as few logically independent concepts and arbitrary relations between them (fundamental laws or axioms) as possible. I shall call this goal that of “logical unity.” Roughly, but honestly, I can also express this second goal as follows: We do not strive to know only how nature [p. 126]
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