Fundamental constants are to define the units in the International System of Units in the future
The second and the metre have already surged ahead. The kilogram, the ampere and the other physical base units are now trying to catch up. This is one way of describing what is currently happening in the world of metrology, in the world of measuring. The International System of Units is facing a redefinition of its foundations: fundamental constants are to serve as the defining reference values for all seven base units and for all derived units in the future. Delicate, unstable objects such as the International Prototype of the Kilogram or completely impractical definitions like the one used for the electric current will then be a thing of the past. The experimental preparations for these new definitions are running at full speed all over the world - and especially at the Physikalisch-Technische Bundesanstalt (PTB). At the next General Conference on Weights and Measures in November 2018 in Versailles, it is expected that this new era will be officially heralded: The new or revised SI will be decides. Half a year later, on 20 May 2019 (on World Metrology Day) the new SI will come into force. The scientific and high-technology communities will benefit from this. Consumers will not notice the changes in their everyday measurements.