My understanding of the mathematics of General Relativity is quite limited. So I am not expecting any mathematically rigorous answers, but what I do understand is that energy curves spacetime, which in turn dictates the motion of energy and mass. I've seen a lot of videos which explain why einstein thought of the universe as 4D space but non of them seem to explain how he related energy, pressure and stress to the curvature of spacetime
- I understand why einstein proposed that energy curves spacetime, but how did he know how much mass curves how much spacetime? I could randomly say that the curvature is linear with radius for a spherical mass which is not true. Where did einstein get his constraint from? that relates energy and curvature?
Is this the conservation of some quantity?