The wave equation of Quantum Mechanics P'(U') = P(U) completely describes the Universe, or more precisely, what we think we can know about the Universe. I'm leaving out all the usual Greek letters here (P is usually "Phi"). U is a vector in Hilbert space, essentially an infinite list of "facts", including the value of every field (gravity, electromagnetic etc) at every point in the Universe. What you pay for rent is in there somewhere. This theory becomes useful if you add another variable, K, which represents a restriction on the wave function to a domain of concern or applicability. The equation then becomes an " effective field theory ", P'(U',K) = P(U,K). K will specify things like velocities much less than the speed of light, gravitational fields weaker than in a black hole etc. K may be so restrictive that things like gravity can be entirely ignored (as in a particle accelerator, where the effect of gravity is vanishingly small c...