time crystals

Normal crystals have an atomic structure that repeats in space - just like the carbon lattice of a diamond. But, just like a ruby or a diamond, they’re motionless because they’re in equilibrium in their ground state. But time crystals have a structure that repeats in time, not just in space. And it keep oscillating in its ground state. Imagine it like jelly - when you tap it, it repeatedly jiggles. The same thing happens in time crystals, but the big difference here is that the motion occurs without any energy. A time crystal is like constantly oscillating jelly in its natural, ground state, and that’s what makes it a whole new form of matter - non-equilibrium matter. It’s incapable of sitting still.

via http://www.sciencealert.com/scientists-have-just-announced-a-brand-new-form-of-matter-time-crystals