Investigating Hidden Worlds
Time crystals repeat themselves in time as well, leading the crystal to change from moment to moment. A time crystal never reaches thermal equilibrium, as it is a type of non-equilibrium matter.
Of all harmonic devices, it [a drone] is not only the simplest, but probably also the most fertile.
— Peter van der Merwe, Origins of the Popular Style: The Antecedents of Twentieth-Century Popular Music
Drone by Wolf Maps.