What Is Real?: The Unfinished Quest for the Meaning of Quantum Physics

by Adam Becker

Everything has a wave function in quantum physics: this book, the chair you’re sitting in, even you. So do the atoms in the air around you, and the electrons and other particles inside those atoms. An object’s wave function determines its behavior, and the behavior of an object’s wave function is determined in turn by the Schrödinger equation, the central equation of quantum physics, discovered in 1925 by the Austrian physicist Erwin Schrödinger. The Schrödinger equation ensures that wave functions always change smoothly—the number that a wave function assigns to a particular location never hops instantly from 5 to 500. Instead, the numbers flow perfectly predictably: 5.1, 5.2, 5.3, and so on. A wave function’s numbers can go up and down again, like a wave—hence the name—but they’ll always undulate smoothly like waves too, never jerking around too crazily.