On the Choice of Fixed Fundamental Constants for New Definitions of the SI Units

Abstract

Different ways of choosing the fundamental physical constants in connection with the planned transition to new defi nitions of the fundamental SI units (kilogram, mole, ampere, and kelvin) are discussed. Criteria for an optimum choice of the fundamental physical constants for this transition are considered. The advantages and disadvantages of the new defi nitions of the kilogram, mole, ampere, and kelvin based on various sets of constants chosen from the atomic mass unit, Avogadro constant, elementary electric charge, Boltzmann constant, Planck constant, and permeability of free space are analyzed.