From an online book where the author tries to discredit GR, there's a part where he talks about forgetting about the rubber sheet analogy and just remembering: "A body moves along the path that makes time dilation a minimum." Then he presents a diagram and a little argument that is really clear. I'm wondering if at least that part is ok or if the whole book is garbage. Link: [...link deleted by bcrowell...] I'm curious because I've been struggling for a way to conduct a lesson on GR for 9th graders and this is the simplest explanation I've come across so far (if correct at all). Thanks and sorry if this is taboo to post. I just don't honestly know enough about GR to criticize this properly.