SI Redefinition and the Role of the CODATA Task Group on Fundamental Constants

Abstract

In November 2018 representatives from over 58 countries will meet to approve a major revision to our international measurement system, the SI. This redefinition will be the most sweeping change in the last 140 years and remove the last defining artifact from the SI. In essence there definition of the SI will set the exact values of seven constants, five of which are fundamental constants of physics. This will intrinsically link physics and metrology, and in doing so improve the accuracy of our primary standards and make them inherently stable in both time and space. But how and who will chose those exact values? I will outline the history and work of the CODATA Task Group on Fundamental Constants, the committee that actually derives those values. I will review the problems that have been faced and how they were overcome and briefly outline the various committees and organizations that have contributed to the process of acceptance and final approval. Finally, I will outline how the measurement transition will be managed and what lies ahead after the redefinition of the SI.