Beyond Weird: Why Everything You Thought You Knew about Quantum Physics Is Different

by Philip Ball

But there was already a mature mathematical theory of classical waves; maybe we could use that to describe the alleged waviness of particles? That’s just what Erwin Schrödinger, a professor of physics at Zurich, did. After being given de Broglie’s thesis and challenged to describe wave-like particles in formal terms, he wrote down an expression for how they might behave. It was not quite like an ordinary wave equation of the sort used to describe water waves or sound waves. But it was mathematically very similar. Why wasn’t it identical? Schrödinger didn’t explain his reason, and it now seems clear that he didn’t exactly have one. He simply wrote down what he thought a wave equation for a particle such as an electron ought to look like. That he seems to have made such a good guess is even now rather extraordinary and mysterious. Or to put it another way: Schrödinger’s wave equation, which is now a part of the core conceptual machinery of quantum mechanics, was built partly by intuition and imagination, albeit combined with a deeply informed sense of which parts of classical physics it was appropriate to commandeer. It can’t be proved, but only inferred by analogy and good instinct. This doesn’t mean that the equation is wrong or untrustworthy; but its genesis shows how creativity in science depends on more than cold reason.