The theory of general relativity holds that a massive body like Earth curves space-time, causing time to slow as you approach the object — so a person on top of a mountain ages a tiny bit faster than someone at sea level.
US scientists have now confirmed the theory at the smallest scale ever, demonstrating that clocks tick at different rates when separated by fractions of a millimeter.
Jun Ye, of the National Institute of Standards and Technology (NIST) and the University of Colorado Boulder, said their new clock was “by far” the most precise ever built — and could pave the