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The CIPM is progressing towards redefining the SI in 2018

“The decision by the CIPM to propose a resolution to the 26th CGPM on the redefinition of the base units in the SI brings the vision of an International System of Units based on invariant constants of nature one step closer to realization. In taking this decision, the CIPM acknowledges the outstanding contributions by many metrologists and the commitments of their institutes to undertake the long-term experiments necessary to make this decision possible.”

Dr Barry Inglis, President of the CIPM

At its meeting on 20 October 2017, the CIPM decided to take the next step towards the expected redefinition of the base units of the SI at the 26th General Conference on Weights and Measures (CGPM), which will take place in Versailles in November 2018.

The CIPM reviewed the work carried out by its Consultative Committees over recent years, and the recommendations received from them that the conditions necessary to progress to redefinition are now fulfilled.

See: Decision CIPM/2017-10


The CIPM also agreed that the latest and final values for the constants that will be used to redefine the SI should be published. These have been calculated by the CODATA Task Group on Fundamental Constants, and have now been published in Metrologia.

See: The CODATA 2017 values of h, e, k, and NA for the revision of the SI

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