Metrology and the Updated SI: Episode I - A New Day
On May 19, 2019, the International System of Units (SI) was changed in a fundamental way so that all the units have their basis in seven defining constants. This was nothing short of colossal, and enabled our familiar, beloved, and world-wide system of units to be more accurate, available and reproducible than ever before. Though few would disagree with the motivations that were behind the redefinition, many metrologists struggle with the practical implications that the redefinition presents in terms of performing measurements that are “traceable to the SI.” In this first of a series of webinar “episodes,” we would like to introduce and explore the redefinition of the SI in 2019 from both theoretical and practical viewpoints. Any coherent system of units is only as good as the measurements that it produces, so it is vital that a metrology practitioner understands exactly how the SI revision affects her own realization and dissemination of the SI. This is a broad topic, but we hope to provide useful information on the changes to all the SI quantities: mass, thermodynamic temperature, length, electrical current, amount of substance, luminous intensity, and time. In subsequent episodes, we plan to give a more detailed discussion of changes to mass, temperature, and electrical current (along with voltage and resistance), as these quantities are most affected by the recent revision.