NIST researchers have conducted the most accurate test yet of a key principle in Einstein’s general relativity theory by comparing different types of remote atomic clocks. The experiment, described in a Nature Physics paper, involved comparing data from 12 atomic clocks around the world over a 14-year period. The results confirmed Einstein’s prediction that all objects in a free-falling elevator would accelerate at the same rate, with a constrained violation of local position invariance (LPI) of 0.00000022 ± 0.00000025 – the most precise measurement yet. The improved accuracy was made possible by more advanced atomic clocks, better time transfer processes, and updated data on Earth’s position and velocity. The findings have implications for fundamental physics and could be further refined using next-generation optical frequency clocks.
Keywords: atomic clocks, general relativity, LPI violation, gravitational field, electromagnetic radiation
