JILA Clocks Detect Time Dilation Across 1 Millimeter, Reaching 10^-21 Precision
Updated
Updated · spacedaily.com · May 20
JILA Clocks Detect Time Dilation Across 1 Millimeter, Reaching 10^-21 Precision
4 articles · Updated · spacedaily.com · May 20
A JILA team led by Jun Ye measured gravitational time dilation across about 1 millimeter, showing atoms lower in the sample ticked measurably slower than those higher up.
The result came from an optical lattice clock using ultracold strontium atoms, with precision near 1 part in 10^21—about 50 times better than previous clock comparisons.
That sensitivity pushes tests of Einstein’s general relativity down to ordinary human scales, where height differences within a room or across a body produce real, if tiny, differences in elapsed time.
Researchers say the same leap in precision could turn optical clocks into ultra-sensitive gravimeters for mapping underground water or geological structures, while also supporting future time standards and searches for new physics.
If our most precise clocks reveal a crack in Einstein's theory, what new physics might we be on the verge of discovering?
With time now measured at the millimeter scale, which industry will be the first to be totally transformed by this new precision?
If your head truly ages faster than your feet, how must we rethink the fundamental nature of our own human experience?
Einstein’s theory of general relativity predicts that gravity slows the flow of time, so atomic clocks tick more slowly at lower elevations where gravity is stronger. This effect, called gravitational time dilation, was previously measured over distances of about 33 centimeters. In 2022, JILA researchers achieved a breakthrough by observing this effect across just 1 millimeter using an extremely accurate atomic clock and hundreds of thousands of strontium atoms. Their experiment confirms that even over tiny distances, gravity can measurably affect time, opening new possibilities for exploring the connection between relativity and quantum physics.