IU15. Bureau International des Poids et Mesures (BIPM)

Report to the 1999 IUPAP General Assembly

1. The 7th edition of the SI booklet issued by BIPM has appeared early in 1998, under the authority of the CIPM and its Comité Consultatif des Unités (CCU). The chairman of this last Committee is I. Mills, a member of our C2 Commission, as three other members of the CCU.

One major new feature of this booklet is to introduce some consideration of general relativity that becomes a matter of concern not only for time and frequency measurements but also for length measurements. This matter has been looked at by a working group of the Comité Consultatif pour la Définition de la Seconde (CCDS) to which our chairman B.W. Petley participated. This working party will pursue its work as a joint committee of CCDS and IAU.

2. The joint Committee for Guides in Metrology (JCGM) already mentioned in the last report has confirmed its support to the action of two working groups. One of them is in charge of preparing a shorter version of the Guide to the Expression of Uncertainty in Measurements, under the chairmanship of our member B.N. Taylor. The second one is chaired by P. Giacomo and involves five other members of our C2, with the aims of preparing a possible revision of the International Vocabulary of Basic and General Trams in Metrology (known as VIM). This second group has started work on a proposal made by an ad hoc sub-group of ISO/TC12 and IEC/TC25 who proposed a complete rewriting of the first chapter of VIM. It is fortunate that IUPAP/C2 is significantly represented in this working group since chapter 1 of the VIM deals with many fundamental physical concepts such as quantities, units, dimension or systems of quantities in their links with measurements. The views of pure physicists and pure chemists are useful to clarify some of these basic concepts. This work will probably extend over some two or three years to come.

P. Giacomo (France)