Joachim Ullrich

Metrology: Understanding and Shaping the World – in a Digital and Interconnected Future

Stefan Hell, Chemistry Nobel Prize 2014

Metrology, the science of measurement and its application, is the foundation of science, technolo-gy, and trade. Since ancient times mankind was aware that there are certain quantities that are measurable, i.e., that can be compared by ratio. For a structured comparison, agreeing on “units” is most convenient. These have been artefacts over thousands of years among them, most promi-nently, the international prototype of the kilogram, the IPK. In 2019, the General Conference on Weights and Measures, CGPM, abolished all artefacts in a revolutionary decision defining the Inter-national System of Units, the SI, by fixing the numerical values of 7 defining constants – a sound basis for digitalization. In the talk, a brief review of the historical development and the foundation of the SI is provided followed by some examples on ever-improving realizations of units based on the revised SI. Being defined by fixing real numbers, the revised SI is the ideal foundation for digitalisation providing the metrological anchor of trusts for the international scientific and quality infrastructure in a digital and interconnected world – the “CIPM Vision on Transforming the International System of Units for a Digital World”. The main part of the talk is dedicated to describing this vision, along with the “The SI Digital Framework” providing the metrological basis for inter-operable digital data within the quality infrastructure. This is followed by highlighting recent developments at the BIPM like the establish-ment of the digital SI Reference Point or ongoing work aiming at the formulation of an axiomatic system of core metrological terms. Finally, the rich future and the role of metrology in digitalisation is envisioned for interconnected measurement systems in cities of the future with smart homes and factories, for autonomous driving, smart health and for providing trust in artificial intelligence e.g., by certifying training and test data sets, defining uncertainty budgets in interconnected sys-tems and much more. All of these topics are addressed in the newly established “CIPM Forum on Metrology and Digitalisation”.