Two independent research teams have achieved a longstanding goal in physics: building a working nuclear clock. The devices, developed by Beichen Huang and colleagues at Tsinghua University and by Luca Toscani De Col and colleagues at the Vienna Center for Quantum Science and Technology in Austria, e xploit the nucleus of a thorium-229 atom to keep time with extraordinary precision—possibly surpassing even the best atomic clocks available today. ...read more read less