# Relativity (1931)

An introduction to Einstein’s space-bending, time-stretching Theory of Relativity, first published in December 1916. Special and General relativity explain the structure of space time and provide a theory of gravitation, respectively. Einstein’s theories shocked the world with their counterintuitive results, including the dissolution of absolute time. In this book, he brings a simplified form of his profound understanding of the subject to the layperson.
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RELATIVITY
THE SPECIAL AND GENERAL THEORY
RELATIVITY
THE SPECIAL AND GENERAL THEORY
BY
ALBERT EINSTEIN, Ph.D. PROFESSOR OF PHYSICS IN THE UNIVERSITY OF BERLIN
TRANSLATED BY
ROBERT W. LAWSON, D.Sc., F. Inst. P. UNIVERSITY OF SHEFFIELD
NEW YORK PETER SMITH
Copyright, 1920 BY HENRY HOLT AND COMPANY
Reprinted, September, 1931, by permission of Henry Holt and Company, Inc.
PRINTED IN THE U. S. A. BY QUINN & BODEN COMPANY, INC, RAHWAY, N. J.
PREFACE
THE present book is intended, as far as possible, to give an exact insight into the theory of Relativity to those readers who, from a general scientific and philosophical point of view, are interested in the theory, but who are not conversant with the mathematical apparatus of theoretical physics. The work presumes a standard of education corresponding to that of a university matriculation examination, and, despite the shortness of the book, a fair amount of patience and force of will on the part of the reader. The author has spared himself no pains in his endeavour to present the main ideas in the simplest and most intelligible form, and on the ​whole, in the sequence and connection in which they actually originated. In the interest of clearness, it appeared to me inevitable that I should repeat myself frequently, without paying the slightest attention to the elegance of the presentation. I adhered scrupulously to the precept of that brilliant theoretical physicist, L. Boltzmann, according to whom matters of elegance ought to be left to the tailor and to the cobbler. I make no pretence of having withheld from the reader difficulties which are inherent to the subject. On the other hand, I have purposely treated the empirical physical foundations of the theory in a “step-motherly” fashion, so that readers unfamiliar with physics may not feel like the wanderer who was unable to see the forest for trees. May the book bring some one a few happy hours of suggestive thought!
A. EINSTEIN
NOTE TO THE THIRD EDITION
IN the present year (1918) an excellent and detailed manual on the general theory of relativity, written by H. Weyl, was published by the firm Julius Springer (Berlin). This book, entitled Raum—Zeit—Materie (Space—Time—Matter), may be warmly recommended to mathematicians and physicists.
BIOGRAPHICAL NOTE
ALBERT EINSTEIN is the son of German-Jewish parents. He was born in 1879 in the town of Ulm, Würtemberg, Germany. His schooldays were spent in Munich, where he attended the Gymnasium until his sixteenth year. After leaving school at Munich, he accompanied his parents to Milan, whence he proceeded to Switzerland six months later to continue his studies. From 1896 to 1900 Albert Einstein studied mathematics and physics at the Technical High School in Zurich, as he intended becoming a secondary school (Gymnasium) teacher. For some time afterwards he was a private tutor, and having meanwhile become naturalised, he obtained a post as engineer in the Swiss Patent Office in 1902, which position he occupied till 1909. The main ideas involved in the most important of Einstein’s theories date back to this period. Amongst these may be mentioned: The Special Theory of Relativity, Inertia of Energy, Theory of the Brownian Movement, and the Quantum-Law of the Emission and Absorption of Light (1905). These were followed some years later by the ​Theory of the Specific Heat of Solid Bodies, and the fundamental idea of the General Theory of Relativity.
During the interval 1909 to 1911 he occupied the post of Professor Extraordinarius at the University of Zurich, afterwards being appointed to the University of Prague, Bohemia, where he remained as Professor Ordinarius until 1912. In the latter year Professor Einstein accepted a similar chair at the Polytechnikum, Zurich, and continued his activities there until 1914, when he received a call to the Prussian Academy of Science, Berlin, as successor to Van’t Hoff. Professor Einstein is able to devote himself freely to his studies at the Berlin Academy, and it was here that he succeeded in completing his work on the General Theory of Relativity (1915–17). Professor Einstein also lectures on various special branches of physics at the University of Berlin, and, in addition, he is Director of the Institute for Physical Research of the Kaiser Wilhelm Gesellschaft.
Professor Einstein has been twice married. His first wife, whom he married at Berne in 1903, was a fellow-student from Serbia. There were two sons of this marriage, both of whom are living in Zurich, the elder being sixteen years of age. Recently Professor Einstein married a widowed cousin, with whom he is now living in Berlin.
R. W. L.
TRANSLATOR’S NOTE
IN presenting this translation to the English reading public, it is hardly necessary for me to enlarge on the Author’s prefatory remarks, except to draw attention to those additions to the book which do not appear in the original.
At my request, Professor Einstein kindly supplied me with a portrait of himself, by one of Germany’s most celebrated artists. Appendix III, on “The Experimental Confirmation of the General Theory of Relativity,” has been written specially for this translation. Apart from these valuable additions to the book, I have included a biographical note on the Author, and, at the end of the book, an Index and a list of English references to the subject. This list, which is more suggestive than exhaustive, is intended as a guide to those readers who wish to pursue the subject farther.
I desire to tender my best thanks to my colleagues Professor S. R. Milner, D.Sc., and Mr. W. E. Curtis, A.R.C.Sc., F.R.A.S., also to my friend Dr. Arthur Holmes, A.R.C.Sc., F.G.S., ​of the Imperial College, for their kindness in reading through the manuscript, for helpful criticism, and for numerous suggestions. I owe an expression of thanks also to Messrs. Methuen for their ready counsel and advice, and for the care they have bestowed on the work during the course of its publication.
ROBERT W. LAWSON
The Physics Laboratory The University of Sheffield June 12, 1920
CONTENTS
Footnotes
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