Unresolved concerns about the “new SI”
The International Committee for Weights and Measures (CIPM) has proposed new definitions of four of the seven base units of the SI. The definitions of the proposed “new SI” have been published  and are available on the BIPM website , and have been the subject of lively discussions in the literature and in private communications. A number of concerns about the new SI have been raised in this journal and elsewhere [3, 4, 5, 6, 7, 8, 9, 10, 11]. We feel that these concerns have not been adequately addressed to date. Since the new SI definitions are to be formally proposed in a resolution to be considered in late October at the General Conference on Weights and Measures, this discussion has some urgency.
In this letter, we focus on the new SI definition of the kilogram and specifically that it fails to meet three of the criteria for a good reference quantity as presented by Mills et al. in Ref.  that (1) it “should preferably be as simple as possible both to comprehend...
KeywordsCesium Base Unit Alternative Definition Exact Mass Acceptable Alternative
- 2.BIPM draft of new SI (2010) http://www.bipm.org/utils/common/pdf/si_brochure_draft_ch2.pdf
- 9.Rusch P (2011) “Redefining the kilogram and mole”, ACS comment, chemical and engineering news digital edition. http://www.cen-online.org, 30 May
- 11.Chemistry International (2011) The kilogram in the “New SI”. http://www.iupac.org/publications/ci/2011/3305/2_kilogram.html