It's official – a kilogram is no longer what it was

The international system of measures has been revised with new definitions for the kilogram and other key units.

At a meeting in Versailles, France, countries voted in favor of adopting the vast changes that underlie vital human activities such as global trade and scientific innovation.

The most closely observed change was the revision of the kilo, the measure of mbad.

Until now, it was the mbad of an iridium platinum block, called Grand K, kept in a safe at the gates of Paris. This is the only true kilo in the world against which all others have been measured since 1889.

The head of the BIPM (International Bureau of Weights and Measures) Martin J.T. Milton holds a replica of the prototype international kilogram at Sèvres, near Paris. The metal cylinder the size of a golf ball, the heart of the global mbad measurement system, is about to retire. (Christophe Ena / Associated Press)

It is now removed and replaced by a new definition based on a scientific formula. In their vote, the countries also unanimously approved the update of three other key units: the Kelvin for the temperature, the amp for the electric current and the mole for the amount of electricity. ;a substance.

The vote was greeted with applause and sustained applause, after the more than 50 countries present said yes or yes to the request one after the other of their decision.