An Alternative Set of Defining Constants for Use in Redefining the Four Units of the International System of Units

Abstract

Different sets of constants the fixed values of which may be selected for new definitions of the four units (kilogram, mole, ampere, and kelvin) of the International System of Units are discussed. The concept of the “order of a constant” in a given system of units is proposed. Criteria for arriving at an optimal selection of defining constants as well as a set of constants consisting of Planck’s constant h, Avogadro’s constant N_A, Boltzmann’s constant k, and the magnetic permeability of a vacuum (magnetic constant) μ₀ are considered. The proposed set is an alternative to the base set consisting of h, e, k, and N_A.