General Relativity 101
Introduction Screenshot of the conversation that instigated this post. The Credible Hulk made a few posts on General Relativity, which is Einstein's theory of gravity. The comment thread to the right (image) ensued. I have taught myself some general relativity, and I am aiming for a Ph. D. that involves general relativity. Can I explain it, even if slightly? I think I can, at least, try to do so. So, here I will try to explain the concepts involved: Riemann Tensor Ricci Scalar Ricci Tensor Christoffel Symbol Energy-Momentum Tensor .. As you can see, general relativity is scary. It really is - one of the standard texts for an introduction course is Spacetime and Geometry by Sean Carroll, and the first four chapters are mathematics. Yet the information contained does have conceptual explanations. There's a familiar one, involving space as a sort of elastic cloth and planets and stars as really heavy balls that dent the fabric. Ho...