Helgoland: Making Sense of the Quantum Revolution

by Carlo Rovelli

This is the significance of Heisenberg’s original intuition: to ask what the orbit of an electron is when it is not interacting with anything is an empty question. The electron does not follow an orbit because its physical properties are only those that determine how it affects something else, for instance, the light that it emits when it is interacting. If the electron is not interacting, there are no properties. This is a radical leap. It is equivalent to saying that everything consists solely of the way in which it affects something else. When the electron does not interact with anything, it has no physical properties. It has no position; it has no velocity.