The SI, a universal language

Abstract

The SI has inherited and developed the fundamental features of the Systéme Métrique: simplicity, universality, and mainly coherence. It has to adapt itself steadily to the new fields and the increasing demand of accuracy, with the constraints of improving its coherence and universality and maintaining the continuity of measurements. The SI cannot ignore such natural units as the day, the turn, and their usual fractions and multiples; they must be tolerated for general use in spite of their incoherence. Such tolerances must be severely restricted. It is the condition for the SI to become and remain a truly universal language common to all fields and all countries. A few simple rules follow that any scientist should keep in mind.