RELATIVITY

THE SPECIAL & THE GENERAL THEORY

A POPULAR EXPOSITION

BY

PROFESSOR OF PHYSICS IN THE UNIVERSITY OF BERLIN

AUTHORISED TRANSLATION BY

ROBERT W. LAWSON, D.Sc.

UNIVERSITY OF SHEFFIELD

WITH FIVE DIAGRAMS
AND A PORTRAIT OF THE AUTHOR

THIRD EDITION

METHUEN & CO. LTD.
36 ESSEX STREET W.C.
LONDON

This Translation was first PublishedAugust 19th 1920
Second EditionSeptember 1920
Third Edition1920[Pg v]

PREFACE

THE present book is intended, as far aspossible, to give an exact insight into the theory of Relativityto those readers who, from a generalscientific and philosophical point of view, are interestedin the theory, but who are not conversant with themathematical apparatus[1]of theoretical physics. Thework presumes a standard of education correspondingto that of a university matriculation examination,and, despite the shortness of the book, a fair amountof patience and force of will on the part of the reader.The author has spared himself no pains in his endeavour[Pg vi]to present the main ideas in the simplest and most intelligibleform, and on the whole, in the sequence and connectionin which they actually originated. In the interestof clearness, it appeared to me inevitable that I shouldrepeat myself frequently, without paying the slightestattention to the elegance of the presentation. I adheredscrupulously to the precept of that brilliant theoreticalphysicist L. Boltzmann, according to whom matters ofelegance ought to be left to the tailor and to the cobbler.I make no pretence of having withheld from the readerdifficulties which are inherent to the subject. On theother hand, I have purposely treated the empiricalphysical foundations of the theory in a "step-motherly"fashion, so that readers unfamiliar with physics maynot feel like the wanderer who was unable to see theforest for trees. May the book bring some one a fewhappy hours of suggestive thought!

December, 1916

A. EINSTEIN