Chinese scientists have engineered a clock so accurate it could lead to a redefinition of the second and an ultraprecise global time standard.
The new optical clock is so accurate that it loses or gains less than one second over roughly 30 billion years.
This means if the clock ran for more than twice the current age of the universe, it would be out only by one second, according to researchers at the University of Science and Technology of China.
Optical clocks can measure seconds to 19 decimal places and are the most precise timekeeping devices currently available,
They measure time by using the frequency of light emitted when electrons transition between energy levels in atoms.
Such clocks provide highly accurate time references for modern technologies such as satellite navigation, telecommunications and precision measurements.
Optical clocks are also used for testing fundamental physics principles as well as for the detection of gravitational waves and dark matter.
Until now, scientists had not been able to make highly accurate clocks surpassing the 10⁻¹⁹ level, which would lose or gain only about a second over tens of billions of years.
With the newly achieved accuracy, researchers could open the door to a range of frontier applications, according to a study published in the journal Metrologia.
The new clock could enable tiny millimetre-level observations of gravity and altitude and monitor deformation of the Earth’s crust, groundwater changes, as well as more precise measurements of volcanic activity.
While the second was originally defined as 86,400th of a day, this wasn’t a precise measurement for scientific applications.
In 1967, with the advent of atomic clocks, the International System of Units in France defined the second as 9,192,631,770 oscillations of the caesium-133 atom.
However, there seemed to be more room for improvement as optical clocks were found to be more precise.
Now, with more accurate optical clocks, new approaches to detecting dark matter could be possible by capturing low-frequency signals potentially induced by dark matter interactions, scientists said.
“This performance meets the 2 x (10^-18) single-clock accuracy requirement for redefining the SI second,” the study noted, adding that it could lead to “high-resolution dark matter searches”.
In order to redefine the second, at least three such optical clocks, with a certain degree of precision and stability, need to be used at different institutions.
Currently two other optical clocks have already passed this milestone and as more such ultra-precise clocks join forces, the criteria to redefine the second could soon be met, scientists said.
