Did you know that the humble kilogramme has, until now, been defined by an object that weighs… one kilogramme? And that the measurement unit of temperature – the kelvin – is based on an intrinsic property of water?
While this has worked for centuries, the world’s leading scientists have found that, over time, these definitions have been shown to not be 100 % stable.
The ISO and IEC 80000 series of standards underpins the harmonization of terms, definitions and symbols of quantities and units used in science and engineeringSo, today, they formally agreed that all of the measurement units will now be defined by constants of nature rather than physical objects – the biggest change in international measurement since 1875.
The definitions are consecrated in the scientific community’s bible, the SI Brochure, published by the Bureau International des Poids et Mesures (BIPM), in which the ISO and IEC 80000 series of standards, Quantities and units – published respectively by ISO and the International Electrotechnical Commission (IEC) – is referenced. The series provides the internationally agreed names, definitions and symbols of quantities used in science and engineering, and their corresponding units, thus guaranteeing a unified language and reducing the risk of error.