Chinese physicists created a time crystal — a cloud of cesium atoms that behaves like an ideal swing. One push — and they keep swinging for 17 hours non-stop, because all friction was eliminated by laser and radio frequency tuning.

The atoms were given a superposition — a mixture of two states at once — and irradiated with precisely tuned radio waves. Their synchronous oscillations were tracked via spectroscopy, and calculations predicted record-low energy losses.

This stability is useful for quantum sensors: they will be able to detect ultra-weak fields. Inside, the entropy (disorder) barely grows, and the system remains ordered as if defying the laws of thermodynamics. This was achieved through quantum optics methods. Even Boltzmann, the father of thermal chaos theory, would not have expected this: his rule of striving for equilibrium fails here.