“The experiments are beautiful and open up a new class of states of matter that really qualitatively are new and fascinating in their own right,” MIT theoretical physicist and Nobel laureate Frank Wilczek told Gizmodo. Wilczek proposed time crystals in 2012, while wondering whether certain properties changing in time, rather than in space, could yield new phases of matter. He said “the new discoveries... are certainly a recognizable descendant of the original vision and have retained the name.”
Physical laws are laden with symmetries—instances where an action produces the same reaction in a different environment. If you punch a solid wall with the same force, it will hurt equally no matter where along the length of the wall you punch it or what time of day it is—those are spatial and time translation symmetries. Some symmetries can break. Crystals, solids where particles arrange themselves in a lattice, break a so-called spatial translational symmetry, since the molecules prefer a specific place in space. If you had a picket fence instead of a solid wall, that might break a spatial translational symmetry, since punching a picket feels different than punching the space between planks.
Wilczek’s idea was simple: Can molecules break time translational symmetry? Can certain solids crystallize in time, preferring different states at different time intervals? That question became: Do certain periodic behaviors of a collection of atoms have preferred tempos? This would kind of be like 17-year cicadas—they could come every year, but instead they break a time translational symmetry, since they clump on the 17th year rather than appearing evenly every year. |