At the conclusion of the lecture announcement was made and enthusiastically cheered that the blackboard used by the speaker and signed by him was to be varnished and preserved as a historic memento.
Einstein holds the primary concept of physics to be that of a rigid body. The idea of space was not known by the Greeks. Behind the geometry of Euclid with its displacement of triangles lay the thought of rigid bodies. With Descartes' analytical geometry science conceived the conception of a space continuum, but it was an entirely mathematical notion. Newton, dealing with force and acceleration, conferred on space a definite physical reality. A further change in the content of the space concept was introduced by Faraday and Maxwell when they discussed the electromagnetic field. This idea joined the former trio of realities, bodies, space and time, and seemed to requirethe setting up of the ether to account for its actions. H.A. Lorentz made great use of the ether though he robbed it of its mechanical properties. Next came the special theory of relativity. "Classical physics used three co6rdinates in space and one in time. It was now found necessary to unite these into the four co6rdinates of space-time, and give up the belief that events could be divided into categories of ' before,' ' simultaneous,' and ' after.' This prepared the way for the general theory of relativity, which dealt with the phenomena of inertia and derived the laws of motion from the geometrical structure of space, or rather of space-time, thus uniting geometry and physics in a new intimacy. The experimental verification of this theory is well known. We have now come to the conclusion that space is the primary thing and matter only secondary; we may say that space, in revenge for its former inferior position, is now eating up matter." In his endeavor to deduce all physical phenomena from the properties of space Einstein recognizes that he has not won the adherence of all physicists. "In fact, he added with a smile, they think that I am crazy on this subject." He continues, however, to seek a series of equations that will comprehend all the field of physics.
G. F. S.