In 2019, the International System of Units (SI) was redefined in terms of constants that relate to the natural world. This assures the future stability of the SI and opens the opportunity for the use ...

Until 2018, the SI unit of mass, the kilogram, was defined as the mass of a real object: the International Prototype Kilogram, kept in a secure facility in the outskirts of Paris. On November 16, 2018 ...

In measuring Planck's constant with the NIST Kibble balance, researchers carefully measured the effects of the magnetic field that is generated to counteract the weight of masses. In their experiments ...

The watt balance—also known as the Kibble balance—is a precision electromechanical instrument that has revolutionised the realisation of the kilogram by linking it directly to the Planck constant.