A glittering hunk of crystal gets its iridescence from a highly regular atomic structure. Frank Wilczek, the 2012 Nobel Laureate in Physics, proposed quantum systems––like groups of particles––could construct themselves in the same way, but in time instead of space. He dubbed such systems time crystals, defining them by their lowest possible energy state, which perpetually repeats movements without external energy input. Time crystals were experimentally proved to exist in 2016.