How Quantum is the Uncertainty Principle?

The Uncertainty Principle is often the physicists first taste of quantum mechanics. The idea that the very position or momentum of an object could ever be unknown or uncertain is like catnip to a mind which has only ever known the Newtonian universe. And yet, even when taught at the undergraduate level, it is often portrayed as quantum weirdness. Maybe it was just slow uptake on my part, but the idea always seemed to just be a fundamental quantum effect, something plucked from the rear of reality and presented on a platter, its true origins unclear. But its not. The uncertainty principle isn’t quantum at all. And I think it’s time we stopped presenting it like it is.

First, a quick refresher of what we’re talking about. The uncertainty principle, in its most common form, states that there’s a fundamental relationship between our knowledge of a quantum particle’s position and momentum. The more we know about the particle’s location in space, the less we know about how its moving, and vice versa. This is a stark removal from our usual experience of the world, where the simultaneous precise knowledge of both the position and speed of, say, a car is crucial to deciding when to cross the street without an unexpected trip to the hospital.

And so, the uncertainty principle is strange. It goes against our intuition about the world around us. But while the…