The standard definition of time is about to change and get a lot more accurate in the near futureCreative Commons

The most precise clocks, which are used to tell global time, are so accurate that they are only off by about one second every 300 million years. Scientists now say that these clocks can be made even more accurate using lutetium, a rare-Earth element.

When humans first started to measure time, it was just a fraction of one day – a 24 hour time period divided by 86,400 (24 hours divided by 60 minutes divided by 60 seconds). That was, however, not accurate enough because the Earth's rotation is not very accurate and varies by slight margins ever so often.

To overcome these slight margins of error, scientists scaled down from a cosmic star to planet scale to the atomic. In 1967, scientists at the International Committee for Weights and Measures set about defining what constitutes a second and according to a report by, it was the exact time taken for a Caesium atom to absorb enough energy for it to get excited or the time it takes to jump from one energy state to the next. This was measured at exactly 9,192,631,770 cycles of microwave radiation. These measurements took three whole years to complete.

The same type of measurement is still used – caesium clocks play an important role in keeping time throughout the globe. They are the reason why GPS is also so accurate. However, in the last ten years or so, scientists have developed "optical clocks", which are more accurate than the Caesium ones. 

Optical clocks are reportedly 100 times more accurate and make use of aluminium or ytterbium and they get excited by higher frequencies of radiation – within the visible light spectrum. Visible light is also a lot faster than microwaves, so there is a lot more data that goes into exciting the atoms, this makes measuring time a lot more precise.

However, while optical clocks are a lot more precise, they are also not too stable and also do not maintain the same level of accuracy in changing environments.

This is where Lutetium – chemical element, atomic number 71, a rare silvery-white metal – comes into play. It was found to be a lot more stable in changes caused by atmospheric temperature and pressure, unlike the aluminium or ytterbium that was first used in optical clocks. 

Lutetium also compensates for "micromotion shift", a slight wiggling of the charged aluminium or ytterbium atoms that cause slight variations in their positions caused by the wave patterns of both microwaves and visible light.

The study was first published in the journal Nature Communications.