Scientists at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) have discovered key conditions that give rise to fast magnetic reconnection, the process that triggers solar flares, auroras, and geomagnetic storms that can disrupt signal transmissions and other electrical activities, including cell phone service. The process occurs when the magnetic field lines in plasma, the hot, charged state of matter composed of free electrons and atomic nuclei, break apart and violently reconnect, releasing vast amounts of energy. This happens in thin sheets of plasma, called current sheets, in which electric current is strongly concentrated.