Scientists have created a clock so precise it could redefine the second.
The strontium optical lattice clock is one of the most accurate timepieces ever made, capable of measuring seconds to 19 decimal places.
To put that into context, if the clock ran for 30 billion years – more than twice the current age of the universe – it would only be off by around a second.
This degree of precison has been possible thanks to significant advances in technology, and represents a major breakthrough in optical clock technology.
What’s more, it signifies a major step towards the goal of changing the official definition of a second within the next decade or so.
Writing in the journal Metrologia, the team said their clock ‘achieves accuracy at the level required for the roadmap of the redefinition of the second’.
Beyond redefining the second, the clock could play a crucial role in various fields, according to the researchers.
For example, it could aid the search for dark matter and even for specific measurements of Earth’s gravitational field, the scientists explained.
The ‘strontium optical lattice clock’ can measure seconds to 19 decimal places – and is so precise it could redefine the second
Time used to be defined as a fraction of a day, with one second representing a 86,400th of 24 hours.
However, because of variations in the Earth’s rotation speed, this is not a very accurate measurement.
The creation of atomic clocks in the 1950s allowed scientists to measure time much more precisely and, since 1967, the second has been defined in the International System of Units (SI) as 9,192,631,770 oscillations of the cesium–133 atom.
While this is incredibly precise, there is still a margin of error as cesium atoms swing back and forth nine billion times per second.
Strontium, however, oscillates at a significantly quicker rate of 700 quadrillion ‘ticks’ per second, making it a much more accurate measurement.
‘This performance meets the 2 x 10^–18 single–clock accuracy requirement for redefining the SI second,’ the researchers wrote.
Two other strontium optical clocks have already passed this milestone, the scientists said.
Having a third means they are one step closer to officially redefining the second.
Optical clocks (pictured) are a type of next–generation atomic clock that are able to measure time incredibly accurately
For the official definition to be changed, at least three optical clocks based on the same type of ‘tick’ and with a certain level of precision and stability need to be in use at different institutions.
The timeline for the proposed redefinition is set by meetings of the General Conference on Weights and Measures (CGPM).
These are held every four years and the committee has been requested to ‘work towards a proposal for the new definition of the second to be presented at the 29th meeting of the CGPM.’
This will be held in 2030.
‘The new achievement provides a viable technological path for developing portable and space–based optical clocks,’ the researchers, from the Chinese Academy of Sciences, said.
‘It could support future applications including tests of fundamental physical laws, next–generation satellite navigation systems and the establishment of a unified ultra–precise global time standard.’
