A Popular Explanation of the Einstein Theory That Approaches an Actual Visualization of the Subject.

The preparation of this essay on the Principle of Relativity has been undertaken after a careful study of practically all the literature hitherto published on the subject purporting to be of a popular or semi-popular nature. With due appreciation of the merit of many of these works, a perusal of them has made it increasingly apparent that the writers have not succeeded in eliminating technical phraseology sufficiently to bring the subject down to the level of the untrained reader, and that a really popular exposition of both the Special and the General Theory is needed.

Notwithstanding the laudable efforts of some to meet this need it is manifest that the public continues to be in the dark and many erroneously suppose that “only twelve men in the world” can really comprehend this new theory of the universe. Even book reviews ofttimes betray a surprising lack of appreciation of the fundamentals of Einstein’s noble contribution to science.

It is the purpose of this booklet therefore, to bring within the scope of visualization, as nearly as possible, the very essence of relativity, and to state its principles in terms devoid of unfamiliar phrases and illustrations. The popular mind is not satisfied with vague statements, mathematical equations and formulæ. It calls for an explanation in words of every day usage, and where a technical term must be employed then a definition of that term in language simple and lucid. To meet these requirements without sacrificing scientific accuracy has been the earnest endeavor of the author.

Acknowledgment is hereby made to Dr. S. I. Bailey and Dr. G. D. Birkhoff of Harvard, Dr. Edward Kasner of Columbia, Prof. Victor Schmidt of Cincinnati, and Dean J. A. Robison of the Oakland Technical High School (Calif.), all of whom have kindly criticized the manuscript and made valuable suggestions for improvement of the text.—W. F. H.

New York, Dec., 1922.