Vision Crystallized in Time
In 2019 Alfred Shapere and Frank Wilczek published a paper in PNAS on “Regularizations of time-crystal dynamics” [1] and together with Peter Hannaford we were invited to write a commentary article [2]. The work by Alfred and Frank concerned a classical time crystal where a particle performed Sisyphus motion in order to minimize its energy. We wanted to start our commentary paper with a humorous paragraph:
The history of scientific discoveries is full of surprising plot twists because it often happens that it is not the person we had in mind who was first to come up with the scientific idea but somebody else who did it earlier. It seems that this is the case with time crystals. We heard that the ideas of time crystals were proposed by Alfred Shapere and Frank Wilczek in 2012 [3, 4]. However, when we dig sufficiently deeply into the literature we find that a long time ago — we do not even know when precisely — there was a guy who invented a time crystal earlier and even demonstrated it experimentally. He was the king of Ephyra, Sisyphus, who was forced to roll a boulder up a hill, and then allow it to roll back down again, which was repeated for eternity. Certainly Shapere and Wilczek were not aware of his discovery otherwise they would have cited Sisyphus in their papers. Probably, in order to give appropriate credit to the king of Ephyra, they decided to write the article about the Sisyphus time crystal which is published in this issue of PNAS [1]…
