The International System of Units (SI), the modern metric system, is set to undergo a major revision with updated values for four fundamental constants of nature. If approved by the General Conference on Weights and Measures (CGPM) in November 2018, the revised SI will enable authoritative measurements to be made anywhere on the planet, based on accurate values of these constants.
The updated values for the Boltzmann constant, Planck constant, charge of the electron, and Avogadro constant were prepared by the Committee on Data for Science and Technology (CODATA) Task Group on Fundamental Constants (TGFC). These values will be fixed and stated as exact values, similar to the current definition of the speed of light.
The revised SI will redefine the seven base units, including the kilogram, kelvin, and ampere. This will eliminate the need for international comparisons of mass standards like Le Grand K, a platinum-iridium cylinder stored in France. The new system will provide a consistent way to define mass across all scales, from atoms to skyscrapers, using the Planck constant.
The revised SI is expected to have minimal impact on everyday life but will significantly change the world of metrology. High-precision measurements will need to be recalibrated, but the official rollout is scheduled for May 20, 2019, to allow metrologists time to adjust.
Keywords: Constants, Metrology, Precision, Standards, Measurements
