Ebook: General Relativity

I am probably a bit biased being that Bob Wald is friend of mine and I am a former student but here it goes.

Wald's book (based on Bob Geroch's lectures) is a wonderfully concise and intuitive book for any inspiring relativist. The cosmology is certainly a bit dated and some comments are correct for the time but no longer apply with the advent of modern computing. Despite these draw backs, his treatment of linearized gravity (ala perturbation theory) as well as the Action Appendix are pure gems. He discusses the Palatini approach and shows that with the Einstein-Hilbert Action that they are one and the same. However, this little section was part of the inspiration to develop modified gravity theories in the Palatini Formalism and to show that they are different than the Einstein Formalism. I particularly enjoyed the Conformal transformation appendix and the Chapters 7 and 9 from his book. As for being an Introduction to GR, I would not recommend it for astrophysics students or classes that are hybrid graduate/undergraduate. It is for serious students of GR. Combined with John Friedman's lecture notes and De Carmo's Differential Geometry text, the student can with what passes for ease begin work in General Relativity.