 Take, for example, Newton’s laws of motion. The 1st law asserts that bodies not acted upon by an external force will move with constant velocity; similarly for the 2nd law and acceleration. These laws seem to presuppose that these are meaningful terms, but in spacetime terms their meaning is given by geometric structures: for instance, constant velocity in Galilean spacetime means having a straight spacetime trajectory. And the problem is not restricted to Newtonian physics; the same point can be made regarding theories that presuppose the Minkowski background spacetime structure, e.g., the quantum field theories of the Standard Model.