What would happen if an electric current no longer flowed, but trickled instead? A new investigation involved cooling their scanning tunneling microscope down to a fifteen thousandth of a degree above absolute zero. At these extremely low temperatures, the electrons reveal their quantum nature. The electric current is therefore a granular medium, consisting of individual particles. The electrons trickle through a conductor like grains of sand in an hourglass, a phenomenon that can be explained with the aid of quantum electrodynamics.