Albert Meets America: How Journalists Treated Genius during Einstein's 1921 Travels

8 Demonstrates with Chalk (April 15–18)

Friday, April 15 Einstein in Lecture Explains His Theory Professor Demonstrates with Chalk As Audience in Horace Mann School Applauds —It’s a Theory of Method—Experience Supplies the Postulates and Reasoning Draws the Conclusions,HeAsserts Professor Albert Einstein lectured on his theory of relativity yesterday for the first time since his arrival in this country before members of the science faculties of Columbia University, and students, in the auditorium of Horace Mann School. He spoke in German, but those anxious to see and hear the man who has contributed a new theory of space and time and motion to scientific conceptions of the universe, filled every seat and stood in the aisles. Professor Einstein was greeted with great applause when he entered the room escorted by Professor M. I. Pupin, Professor George B. Peagram, and Dean Woodbridge of the science schools. Professor Pupin introduced him as the discoverer of a theory which is “an evolution, not a revolution of the science of dynamics.” In discussing the abstract conceptions of his theory, Professor Einstein showed himself possessed of a sense of humor, for he several times brought chuckles and laughs from his audience by his references to the “idiotic” behavior of certain bodies in accelerated systems. Also he caused much amusement when he wished to erase some diagrams he had drawn on the blackboard and made futile motions in the air with his hand until Professor Pupin came to his rescue. But for the most part, his audience listened 8 Demonstrates with Chalk ) to him with the absorption of men of science listening to a brother scientist expound a theory which may alter all their conceptions of motion and space. Not a Closed Theory “The relativity theory is not a closed theory, but a theory of method in which experience supplies the postulates and reasoning draws the conclusions ,”said Professor Einstein. Special relativity, he said, endeavored to find laws to account for the inability to detect absolute motion. From a purely descriptive point of view every motion was relative. It was impossible to describe the motion of a point except by its relation to another point.If two systems were moving past each other uniformly, either might be looked upon by the observer on one as at rest, with the other in motion. Thebasisof relativitywasNewton’sfirstlawof motionthatabodymoved in a straight line with uniform velocity when far away from other bodies. Professor Einstein set up two co-ordinate systems, which he sketched on the blackboard to show that the motion which one particle in a system bears to another particle in another system may result in a curve. In ordinary mechanics only one system was permissible, the second system being permissible only when it moved with uniform motion relative to the first. The mechanics of Newton and Galileo embodied the special relativity principle, he said. There was no cause for doubt of this law in the mechanical field until electric and optical phenomena were examined. Refers to Maxwell’s Theory Light traveled in a straight line with uniform velocity in space, said Professor Einstein, referring to Maxwell’s theory of optical phenomena. He inquired in what co-ordinate system Maxwell’s laws held, and how might the system be moving? If one co-ordinate system, which he sketched, moved with respect to the other, it should be expected that the velocity would be less if the second system moved in the direction of light. If this were true special relativity would be violated because absolute motion could be detected . Michelson’s experiment, however, showed that the velocity did not change and the special relativity principle held in electrical phenomena as well as in pure mechanics. This introduced a theoretical difficulty into electromagnetic theory, as formulated by Maxwell, who predicted change. Demonstrates with Chalk (April 15–18) ) 93 94 ) Albert Meets America Relativity doubted “simultaneity” where applied to two events in different places. There must be a method of determining simultaneity. A physical relation between the events was necessary. Relativity relinquished the absoluteness of simultaneity. In explaining this, Professor Einstein drew a line to represent a rod, its middle point to be determined by measurement. Simultaneous events took place at the ends when seen together from the middle, thus furnishing a criterion of simultaneity. To find the centre there must be a measure. Simultaneity held only for the special co-ordinate system ; if it was simultaneous for one system, it...