Researchers at the University of Science and Technology of China (USTC) have developed a strontium optical lattice clock capable of measuring time to 19 decimal places. The device, which operates with an uncertainty of 9.2 x 10⁻¹⁹, meets the criteria for redefining the second in the International System of Units (SI).
This level of precision-where the clock would drift by less than one second over 30 billion years-could revolutionize timekeeping, geodesy, and dark matter detection.
The USTC’s clock joins two other strontium-based clocks and two aluminum-ion clocks that have already surpassed the required accuracy. With more such systems coming online, the General Conference on Weights and Measures is expected to propose a new definition of the second at its 2030 meeting.