A consistent unified framework for the new system of units: Matter–wave optics

Abstract Thanks to considerable progress in quantum techniques, it has been possible to redefine all SI base units from fundamental constants. A last challenge is to produce a unified framework for fundamental metrology in which all base quantities and relevant fundamental constants appear naturally and consistently. We suggest a generalized 5D framework in which both gravito-inertial and electromagnetic interactions have a natural geometrical signification and in which all measurements can be reduced to phase determinations by optical or matter–wave interferometry. The corner stones of this unification are action and entropy. The connection is made with Kaluza's 5D theory and Planck's natural units.