What are space time crystals?

A time crystal or space-time crystal is a structure that repeats in time, as well as in space. Normal three-dimensional crystals have a repeating pattern in space, but remain unchanged as time passes. read more

Such a rotating ring is periodic both in space and in time and so becomes a space-time crystal. The idea of a permanently rotating ring might have uncomfortable parallels with a perpetual motion device. But a space-time crystal does not violate any laws of physics. read more

Time crystals realize new order of space-time Two teams of experimentalists have created exotic patterns, repeating in time, that represent a new order of space-time previously thought impossible. read more