INTERCONTINENTAL OPTICAL CLOCK COMPARISON

SETS STAGE TO REDEFINE THE SECOND

- 

Because they can enumerate one second up to around 18 decimal places, scientists expect optical clocks will become the world's new time standard around 2030

Researchers from around the world have completed the world's largest, most demanding head-to-head comparison of clocks in history to build confidence for the upcoming redefinition of the second.

The duration of a single second is currently defined by caesium (Cs) atomic clocks. Lasers 'count' the radiation emitted by Cs atoms in these devices to measure one second, give or take a few billionths. As the applications of atomic clocks have expanded — including GPS navigation, climate science, and radio astronomy — expectations of their performance have also increased, necessitating the more advanced optical clocks.

Scientists around the world have been studying and testing these next-generation devices. Because they can enumerate one second up to around 18 decimal places, scientists expect optical clocks will replace Cs atomic clocks as the world's new time standard around 2030. Until then, however, optical clocks will have to pass rigorous tests attesting to their ability to work in step from different parts of the world.

The new effort presents the largest, most sophisticated such test to date. It involved 10 optical atomic clocks on three continents and 65 researchers.

New portable atomic clock offers very accurate timekeeping at sea

SI unit of time

To measure the passage of time, strike up a conversation with the person next to you. If it's riveting, time will fly. But if it advances in painstaking steps, time will slow to a crawl.