Publisher's Synopsis
THE beginning of the twentieth century presented us with a scientific theory which quickly became celebrated all over the world: the Einstein Theory of Relativity. Whoever is interested in the evolution of mental progress will desire to know more of this theory, surrounded though it be by a mailcoat of mathematical formulae, that presents to every non- mathematician an apparent barrier to further investi- gation. Such a truly great idea, however, which contains matter of interest to mankind at large, must be capable of being rendered clear and intelligible, without con- sisting solely of a maze of mathematical formulae. This certainly applies to the Theory of Relativity; all the essential traits of the theory can be made clear without the aid of mathematics to those who have a fair amount of geometrical training, and, in point of fact, a number of such popular expositions have already found their way into current literature. The purpose of the present book is not to give an account of mere details appertaining to the theory, vi THE IDEAS OF EINSTEIN'S THEORY but rather to give a complete and coherent exposition of the whole, at the same time avoiding all mathe- matical accessories. The reader must not only be able to imderstand what is meant when we maintain that the space surrounding gravitational masses suffers curvature - DEGREEShe must be made to see how Einstdn was bound to arrive at such a conclusion. Hence we must follow up the logical connection of the whole theory, commencing with the Special Principle of Relativity in its most simple and primitive form, and leading up to the far-reaching speculations on the finiteness of the universe, along the path taken originally by Einstein. In order to remain intelligible to the layrhan, logical operations based on mathematics must be passed over, and it suffices to say that the suppositions A and B lead us, with the help of mathematical deductions, to the fact C, and later on to D, and so on. By arguing thus, and inducing conclusions to follow each other in right succession, like the links of a chain, we shall perhaps enable the reader to gain a more lucid view of the matter, than by going deeply into mathematical operations and losing count of what is most essential. The present book, though written primarily for lajmien, may also be useful to those who are versed in the theory from the mathematical point of view, but who may find it convenient to supplement their knowledge of the general aspects of the subject. One thing more must be considered. A serious PREFACE vii exposition of the theory will not only have to lay stress on the fact of how very revolutionary Einstein's theory is from the point of view of principle and theory, but must also indicate how very non-revolutionary it appears from a practical point of view. The phs DEGREESsical results of the theory which appertain to those pheno- mena with which we have to do in 4aily and in technical life diverge so slightly from those of former theories. that these last can be further retained with fuU justi- fication for aU practical purposes. The astronomer, therefore, with few exceptions wiU continue to calculate according to the Newtonian theory, the man of science will go on using Maxwdl's equations, and little will be altered. But the mental foimdations of the complete system of physics have been entirely changed. This will be elucidated by numerical examples, so as to dispel wrong and handful ideas of the theory on the part of the reader. J. H. T.
