(
Physikalisch-Technische Bundesanstalt (PTB)) From 20 May 2019 on (World Metrology Day 2019), natural constants will be the measure of all things when it comes to defining what exactly a kilogram, an ampere, a kelvin and a mole exactly are. After years of research at the major metrology institutes, and in particular at the Physikalisch-Technische Bundesanstalt (PTB), the world community eventually agreed upon this revision of the International System of Units, the SI -- a revision that comes into force as of on World metrology Day.
