The Einstein field equations appear very simple, but they encode a tremendous amount of complexity. What looks like one compact equation is actually 16 complicated ones, relating the curvature of spacetime to the matter and energy in the universe. It showcases how gravity is fundamentally different from all the other forces, and yet in many ways, it is the only one we can wrap our heads around. Although Einstein is a legendary figure in science for a large number of reasons — E = mc², the photoelectric effect, and the notion that the speed of light is a constant for everyone — his most enduring discovery is also the least understood: his theory of gravitation, general relativity. Before Einstein, we thought of gravitation in Newtonian terms: that everything in the universe that has a mass
