Time crystals were first theorized in 2012 by Nobel laureate Frank Wilczek. After enough discussion and fleshing out by other theorists, the experimental physicists had enough to work with and began devising contraptions that would perform as a time crystal. Notably, it was roundly decided that such crystals could not exist in an equilibrium state, where all forces are perfectly balanced — after all, by definition, an equilibrium is characterized by an unchanging state, which means it would be perfectly symmetrical in time and couldn't possibly exhibit anything close to violating conservation of energy.
But nonequilibrium thermodynamics is a relatively new and hot field of physics, where systems are kept in a constant, perturbed state to see what happens. And it's here that researchers were able to develop the first time crystal, by making an electron hop around a ring of molecules by zapping it with a laser. That may not sound impressive, until you realize that the electron hopped around at a particular frequency independent of the zappiness of the laser — an indication that the system had found its lowest-energy state, called a ground state, and that time crystalness had been achieved.
But the law of conservation of energy is violated by these Time Crystals. •
Reference: Science Report- University Of Maryland