“functions evolve, called Schrödinger’s equation. We can express Schrödinger’s equation in words as: “The rate of change of a wave function is proportional to the energy of the quantum system.” Slightly more specifically, a wave function can represent a number of different possible energies, and the Schrödinger equation says that high-energy parts of the wave function evolve rapidly, while low-energy parts evolve very slowly. Which makes sense, when we think about it. What matters for our purposes is simply that there is such an equation, one that predicts how wave functions evolve smoothly through time. That evolution is as predictable and inevitable as the way objects move according to Newton’s laws in classical mechanics. Nothing weird is happening yet.”