New international system of units, SI

Abstract

On November 16th, 2018, during the 26th meeting of the General Conference on Weights and Measures (CGPM) in Versailles, the new International System of Units, SI, was approved. In the new system, all seven units of measurement are defined by universal constants making the system independent of the properties of materials, as well as the place and time of the individual units realization. The four basic units - kilogram, ampere, kelvin and mole - were re-defined in terms of the following physical constants: the Planck constant h, the elementary charge e, the Boltzmann constant k and the Avogadro constant NA, respectively. In the present paper, a brief history of system of units is presented, and information on the activity of scientists and the International Bureau of Weights and Measures that led to the re-definition of the system is provided.