Fundamental Ideas and Problems of the Theory of Relativity

Albert Einstein’s Nobel Lecture, Fundamental Ideas and Problems of the Theory of Relativity, was delivered to the Nordic Assembly of Naturalists at Gothenburg on July 11, 1923. The lecture says that the whole development of the theory turns on the question of whether there are physically preferred states of motion in Nature. The lecture adds that concepts and distinctions are only admissible to the extent that observable facts can be assigned to them without ambiguity.

On physically preferred states of motion in reference to extensive regions, the lecture says that from the viewpoint of classical mechanics the answer is in the affirmative, and that the preferred states are those of the inertial frames. The lecture says that gravitational field and metric are only different manifestations of the same physical field. The speaker says he does not know whether the formal connection so derived can really be regarded as an enrichment of physics as long as it does not yield any new physical connections.