This installment of Free Online Math Materials dips into physics to bring you two Project Gutenberg (PG) ebooks on Einstein's general relativity.
Relativity: The Special and the General Theory, Third Edition is a 1920 translation by Robert W. Lawson. In the preface, Einstein writes: 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!
Project Gutenberg (PG) offers two other versions of this book, as well: A 2004 digitization by Brian Basgen and Jeroen Hellingman, revised in 2022 by Richard Tonsing, and an audio book released in 2009.
The Meaning of Relativity is a 1922 translation by Edward Plimpton Adams. The book contains four colloquium lectures on relativity delivered at Princeton in 1921. These lectures are not without mathematics, yet do start from intuitive physical principles and should be largely accessible to students who have experience with multivariable calculus.
These books are two of my earliest solo productions (not at Distributed Proofreaders) for PG. In 2023 and 2024, Laura Natal Rodrigues kindly converted both ebooks from PDF to HTML+SVG to better accommodate variable screen sizes of ebook readers. The PDF of The Meaning of Relativity appears not to be available any longer from PG, but may be downloaded from the preceding link.