Foundation for the redefinition of the kilogram

Abstract

The redefinition of the kilogram, expected to be approved in the autumn of 2018, will replace the artefact definition of the kilogram by assigning a fixed numerical value to a fundamental constant of physics. While the concept of such a change is pleasing, the mass community as represented by the Consultative Committee for Mass and Related Quantities (CCM) was faced with a number of technical and procedural challenges that needed to be met in order to profit in any meaningful way from the proposed change. In the following, we outline these challenges and how the CCM has met and is meeting them. We focus especially on what the mass community requires of the new definition and the process by which the CCM has sought to ensure that these needs will be met.

How to tell the difference between a model and a digital twin

“…The Kibble balance is one of the experiments that will be used to realise the SI unit of mass, the kilogram, following the redefinition of some of the SI base units on 20th May 2019. Previously the kilogram was defined as the mass of a platinum-iridium cylinder kept in Paris, but after the 2019 redefinition it is now defined in terms of a fixed value of the Planck constant and can be realised with any suitable experiment [4]. The realisation typically occurs at a National Measurement Institute (NMI) level, and is cascaded to end users through a traceability chain.…”

Advancing Science for 100 Years

“…It also influenced the derived quantities such as force, density, and pressure. Consequently, for the past 25 years, several NMIs worked to replace the IPK with a definition based on a fundamental constant of nature [Richard et al, 2016].…”

Contributions of precision engineering to the revision of the SI

“…These prerequisites are: o 3 experiments for h with u < 5 × 10 -8 o at least 2 independent methods o all results in agreement within their uncertainties o 1 experiment with u < 2 × 10 -8 The two independent methods mentioned by CCM which could potentially provide experimental data for h with u < 5×10 -8 or even u < 2 × 10 -8 are the so-called Kibble balance or watt-balance experiments and the Avogadro experiment. Following the CCM approach, CCM and the CCU jointly published a roadmap with the necessary steps to prepare for a possible redefinition of the kg [32,157].…”