The group led by Fabrizio Carbone at EPFL and international colleagues have used ultrafast transmission electron microscopy to take attosecond energy-momentum resolved snapshots (1 attosecond = 10-18 or quintillionths of a second) of a free-electron wave function. Though unprecedented in itself, the scientists also used their experimental success to develop a theory of how to create electron flashes within zeptosecond (10-21 of a second) timeframes, using existing technology. This breakthrough could allow physicists to increase the energy yield of nuclear reactions using coherent control methods, which relies on the manipulation of quantum interference effects with lasers and which has already advanced fields like spectroscopy, quantum information processing, and laser cooling.