By using a rare thorium nucleus as a timekeeper, physicists have demonstrated the first working nuclear clock, a device that could lead to even more precise clocks and new ways to search for dark matter.
Source: [Live Science](https://www.livescience.com/physics-mathematics/particle-physics/the-worlds-first-nuclear-clock-just-ticked-on-and-it-could-help-detect-a-fifth-fundamental-force-of-physics)