A landmark day for the metrology community and NPL
The 20 May 2019 is the first day of the redefined International System of Units (SI). This change has been eagerly awaited by the entire international metrology community and represents one of the most significant changes to the SI since its creation.
From 20 May, definitions of four units (the kilogram, the ampere, the kelvin and the mole) will be revised. This means that the definitions of all the SI units will be linked to constants of nature, not physical artefacts. This will guarantee their stability and universality.
Over the past 30 years, NPL has been at the forefront of the international, collaborative research that comes to fruition today.
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