Comments on redefinition of SI units based on fundamental physical constants with fixed values

TL;DR

This paper analyzes the pros and cons of redefining SI units using fixed fundamental physical constants, proposing an optimal set of constants for the redefinition, including the speed of light, hyperfine transition, Avogadro constant, carbon-12 mass, and electron charge.

Contribution

It introduces a minimal optimal set of fixed physical constants for SI redefinition and discusses criteria for selecting these constants.

Findings

Proposes an optimal FPC set for SI redefinition.

Provides criteria for choosing fixed physical constants.

Discusses implications for kelvin redefinition.

Abstract

Advantages and disadvantages of fixation of fundamental physical constants' values for definition of SI units are considered. The case with a new definition of the mass unit on the base of a fixed value of the Avogadro constant is studied in detail. Criteria on choosing of a optimum FPC set with fixed values for the redefinition of the SI units are suggested. The minimal optimum FPC set that is consistent with the criteria is presented. The set comprises the speed of light, the constant of the ground state hyperfine transition of the caesium-133 atom, the Avogadro constant, the mass of the carbon-12 atom and the absolute magnitude of the electron charge. Comment on the redefinition of the kelvin is also made.