Researchers are attempting to build the world’s first nuclear clock. This is a view inside the vacuum chamber that holds crystals doped with the isotope thorium-229, which can be excited by a laser.Credit: Ye Labs/JILA/NIST/University of Colorado Denver, Colorado Physicists are getting closer to creating a long-sought ‘nuclear clock’. This device would keep time by measuring energy transitions in the nuclei of atoms and could become the most precise clock on the planet. Decades ago, scientists predicted that the isotope thorium-229 could be used in such a clock, but they couldn’t pin down its unusual nuclear energy transition. That feat, achieved with a laser in 2024, started the countdown to a nuclear clock. ‘Nuclear clock’ breakthrough paves the way for super-precise timekeeping Now, such a clock is “way closer than people think”, says Eric Hudson, a physicist at the University of California, Los Angeles, who is working on one.…