Physical action is a spacetime bivector. Based on this single assumption, this paper argues that spacetime itself is responsible for much of physics. The properties of its elements and their derivatives, especially the transformations of special relativity, allow us to successively derive and confirm major empirically found laws and equations. We exemplary derive equations for electromagnetism including: Biot-Savart Law, Electrostatic Force, Lorentz Force, Maxwell's Equations including charges, and also constants like the fine-structure constant, electric permittivity, and even additional terms that are related to spin. In strict analogy, we gain very similar equations for gravitation which, e.g., include Poisson's equation for gravity. A further derivation of these equations of gravitation leads to field equations which are comparable to the field equations of general relativity. Electromagnetism and gravitation unite into one set of equations. The fact that bivectors can be written as wave equations also unify classical physics with wave mechanics.