Hi all - glad I found this forum. I'm trying to understand GR 15 years after I graduated from university. I studied Engineering, but all we ever did in relativity was a section on SR in the 'Modern Physics' course. Watching 'Interstellar' rekindled my interest in physics :-). I've bought Schultz's First Course in GR, and am struggling with what I am experiencing as half-explained derivations, so there'll be a lot of questions from me on this forum!