*Project Gutenberg*. Public domain.

## Part II: The General Theory of Relativity

18. Special and General Principle of Relativity 19. The Gravitational Field 20. The Equality of Inertial and Gravitational Mass as an Argument for the General Postulate of Relativity 21. In What Respects are the Foundations of Classical Mechanics and of the Special Theory of Relativity Unsatisfactory? 22. A Few Inferences from the General Principle of Relativity 23. Behaviour of Clocks and Measuring-Rods on a Rotating Body of Reference 24. Euclidean and non-Euclidean Continuum 25. Gaussian Co-ordinates 26. The Space-Time Continuum of the Speical Theory of Relativity Considered as a Euclidean Continuum 27. The Space-Time Continuum of the General Theory of Relativity is Not a Eculidean Continuum 28. Exact Formulation of the General Principle of Relativity 29. The Solution of the Problem of Gravitation on the Basis of the General Principle of Relativity

## Part III: Considerations on the Universe as a Whole

30. Cosmological Difficulties of Netwon’s Theory 31. The Possibility of a “Finite” and yet “Unbounded” Universe 32. The Structure of Space According to the General Theory of Relativity

Appendices:

01. Simple Derivation of the Lorentz Transformation (sup. ch. 11) 02. Minkowski’s Four-Dimensional Space ("World”) (sup. ch 17) 03. The Experimental Confirmation of the General Theory of Relativity 04. The Structure of Space According to the General Theory of Relativity (sup. ch 32) 05. Relativity and the Problem of Space

Note: The fifth Appendix was added by Einstein at the time of the fifteenth re-printing of this book; and as a result is still under copyright restrictions so cannot be added without the permission of the publisher.

## PREFACE

(December, 1916)

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