Time Crystals (Theory)

Frank Wilczek's 2012 proposal that a quantum system could spontaneously break time-translation symmetry, forming a periodic structure in time analogous to how an ordinary crystal breaks spatial-translation symmetry. Bare "time crystal" collides badly with unrelated crystallography ("real-time crystal size measurements") and even film-theory literature ("The Scattering of Time [in] Crystals: Deleuze, Mysticism and Cinema"); a "symmetry breaking" qualifier is required for a clean signal.