Here we have a collection of Albert Einstein’s lectures delivered in Princeton University back in 1921. The book is basically introduction to both special and general theories of relativity plus an introduction on the pre-relativity physics.
The book is quite simple, with almost no diagrams, but the style is readable and clear. As for the pre-requisites to understand the content of the book, I would recommend knowing at least the basics of special relativity and, of course, Newtonian dynamics. However, to understand general relativity, at least a couple years of college physics are needed, so the second part of the book is mostly recommended for science students.
Also check out the website called The Gutenberg Project, which has the book, among many others, hosted on it. It’s a website dedicated to open source and public domain books and audio books, which has thousands of books free.
Category: Free eBooks