Optical clock makes moves on fresh insights into Earth

A European team including researchers from the UK’s National Physical Laboratory carried out the experiment using one of the world’s only transportable optical atomic clocks.

According to Einstein’s Theory of Relativity, clocks closer to massive bodies run slower, meaning a clock at the bottom of a mountain will run more slowly than one at the top.

Optical clocks are now so precise that they are sensitive to these changes, meaning the technique can be used to accurately measure height differences as small as 1cm across Earth’s surface.

Unlike satellite-based measurements, which average the gravity potential over large distances, optical clocks can make measurements at specific locations. And with a transportable clock, these measurements can be taken at points of particular interest, according to Helen Margolis, fellow in optical frequency standards and metrology at NPL.

In this way, the technique could be used to monitor changes to Earth’s gravity potential caused by climate change, for example.