Einstein's field equations are a system of extremely nonlinear partial differential equations. Actually using them to compute something is very nontrivial. And

Einstein's field equations are a system of extremely nonlinear partial differential equations. Actually using them to compute something is very nontrivial. And of course gravity is but one of the many forces at play here. You still have to account for thermodynamics, chemistry, nuclear physics, and other complicated effects to understand what's going on here.