New type of atomic clock keeps time even more precisely December 19, 2020MIT The design, which uses entangled atoms, could help scientists detect dark matter and study gravity’s effect on time. Atomic clocks are the most precise timekeepers in the world. These exquisite instruments use lasers to measure the vibrations of atoms, which oscillate at a constant frequency, like many microscopic pendulums swinging in sync. The best atomic clocks in the world keep time with such precision that, if they had been running since the beginning of the universe, they would only be off by about half a second today.