The New SI and the CODATA recommended values of the fundamental constants 2017 compared with 2014, with a Comment to Possolo et al., Metrologia 55 (2018) 29

TL;DR

This paper discusses the 2017 CODATA adjustment of fundamental constants, comparing it with the 2014 values, and comments on the implications for the revision of the SI units, highlighting methodological and conceptual issues.

Contribution

It provides a detailed analysis of the 2017 CODATA recommended values, their differences from 2014, and comments on the methodology and implications for SI revision.

Findings

2017 CODATA values differ from 2014 recommendations

Discussion on the impact of these values on SI revision

Comment on the methodology and conceptual issues in CODATA adjustments

Abstract

This note comments on the special CODATA 2017 adjustment of the fundamental constants of July 2017 involved in the revision of the SI (based on: P.J. Mohr et al., Data and Analysis for the CODATA 2017 Special Fundamental Constants Adjustment for the Revision of the SI, Metrologia 2018, September 2017 preprint), with a comparison to the CODATA 2014 adjustment. In Appendix, a comment is also added on the paper Possolo et al., Metrologia 55 (2018) 29 on the Planck constant. The previous versions of this manuscript (also available on ArXiv) were aiming at pointing out some standing features of the present and future CODATA method in the light of the CODATA table of 2014 recommended values for the fundamental constants. A comprehensive discussion on this and related issues is becoming very important in view of the foreseen revision of the International System (SI) of measurement units in 2018. The present features may still raise doubts on a possible mixing of physical reasons of general validity in science with some needs specific of legal aspects of metrology concerning the SI. This illustration was adjourned in version 3 (v3) according to the CCU 2016 draft of the 9th SI Brochure and to the outcomes of its 22th meeting, with a note about the intended need of a 8th digit in the stipulated value of k.