Hey, all! So, a friend of mine recently bought a shirt with a bunch of random, nonsensical formulas on them and it kind of seemed odd to me. So I had an idea for a T-shirt design with proper formulas... The basic, fundamental equations and laws of physics as we know them now. So far I have Newton's laws, Lagrangian and Hamiltonian mechanics, Maxwell's equations, the laws of thermodynamics, Schrödinger's equation and Einstein's field equations for general relativity. What else am I missing? What are the most general principles or equation(s) in QFT/QED? Thanks in advance!