At the 26th meeting of the General Conference on Weights and Measures (CGPM), the international community adopted a fundamental revision of the International System of Units (SI) in Versailles today. As from 20 May 2019, new definitions of the base units of the SI, including kilogram, kelvin and ampere, will apply for the 60 Member States and the 42 Associate States of the BIPM, which was founded back in 1875 when the Metre Convention was signed.
said: "In daily life, we all take weights and measures for granted. Therefore it is all the more important that we have clearly defined, precise and internationally . This is the precondition for trade and a functioning world economy. The revision of the International System of Units that was adopted today lays the foundation for a modern, knowledge-based system."
Following the decision taken by the CGPM, base units like the kilogram will in future be deduced from constants of physics and nature. As a consequence, they can basically be realised anywhere, at all times and with utmost precision. At present, prototypes of the kilogram still need to be compared with the International Prototype Kilogram (IPK) in a time-consuming process. In addition, the mass of these prototypes changes in the course of time. As early as in 1900, Nobel Physics Prize Laureate Max Planck called for universal units that would apply for all times and for all cultures, including extraterrestrial and non-human ones.
The new base units, however, will not affect daily life. The underlying constants of nature for the base units have been newly defined with very precise measuring methods in many years of scientific work. Numerous metrology institutions worldwide, including Germany's National Metrology Institute (PTB), were involved.