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While remarkable progress has been made over the last few years, the conditions for adopting the redefinitions, as set by the CGPM at its 23rd meeting (2007), have not yet been fully met.
At its 20th meeting (2010), the CCU recognized that there remained small but significant discrepancies between the value of the Planck constant deduced from watt balance experiments and that which was likely to be announced from the Avogadro silicon 28 work in the near future*, and it was, therefore, premature to recommend the redefinition of the units. The CCU preferred neither to discuss nor to make recommendations as to the date at which such a redefinition will take place or the conditions to be satisfied before adopting the new definitions.
However, the CIPM shared the CCU's opinion that it is now time to declare to the wider scientific and user public exactly what is likely to be proposed, so that it can be properly and openly discussed. Resolution 1 adopted by the CGPM in 2011 takes note of the CIPM's intention to propose a revision of the SI, and sets out a detailed road-map towards the future changes.
Resolution 1 invites the CIPM to make a proposal to the CGPM for the revision of the SI "as soon as the recommendations of Resolution 12 of the 23rd meeting of the General Conference are fulfilled".
For full details the reader is referred to the formal text of the Resolution.
*. This result has since been published:
Andreas B., Azuma Y., Bartl G., Becker P., Bettin H., Borys M., Busch B., Gray M., Fuchs P., Fujii K., Fujimoto H., Kessler E., Krumrey M., Kuetgens U., Kuramoto N., Mana G., Manson P., Massa E., Mizushima S., Nicolaus A., Picard A., Pramann A., Rienitz O., Schiel D., Valkiers S., Waseda A., Determination of the Avogadro constant by counting the atoms in a 28Si crystal, Phys. Rev. Lett., 2011, 106, 030801
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Summary
