Changes
:The math is way out of my depth, but I tried clarifying the section about Eddington's experiment. It now says what I think it said - if I'm way off-base, please correct me. -- [[User:EvanW|EvanW]] 19:01, 13 November 2009 (EST)
::Yep, everything in there seems okay. Can't wait to read the rest of the article.--[[User:DanHutchin|DanHutchin]] 19:14, 13 November 2009 (EST)
:::Yeah, I'm struggling with the math. The math of general relativity is hellishly complex, to the point where only a small number of exact solutions have been found in nearly a century. But I think ''examining'' the mathematics, even if it's in a superficial way, could really help the motivated student understand what the theory ''means,'' and to understand what it does and doesn't predict. I'm not planning to dive into covariant and contravariant tensor transformations or the expansion of the Christoffel symbols, but I'm trying to provide a sort of nickel tour of the equations. To your right, we see the stress-energy tensor; it's like mass. To your left, we see the Ricci tensor; it's a contraction of one of the vector fields of the Riemann with its dual, leaving the fully traceless Weyl tensor to describe gravitational radiation and yeah, I think you see my point. It's challenging.
:::But the math is so ''pretty.'' Really, it's like a jigsaw puzzle, and every piece has a really clear physical interpretation. ''This'' piece describes how the volume of a sphere in curved spacetime differs from the volume of a sphere in flat spacetime; it's a direct representation of the shape of spacetime in a gravitational field. ''This'' piece represents the plain, old, warm-and-friendly Pythagorean theorem; it's really no more complicated than that! ''This'' slot here is where you put the energy of the vacuum in order to model a vacuum-dominant expanding universe. The math is ''gorgeous,'' and I want to find a way to share that with kids without boring them or scaring them off.
:::Anyway, the Mercury thing really deserves its own section under tests of general relativity, I think. It's such an important prediction from the points of view of astronomy, theoretical physics ''and'' the modern history of science. I'll turn my attention to it after I finish the quantitative section, unless somebody wants to dive into it.
:::Thanks for the feedback, you guys! Enjoy your Friday night. --[[User:KSorenson|KSorenson]] 19:25, 13 November 2009 (EST)
