SI, today is ‘the’ day

World Metrology Day – 20 May –

The theme for World Metrology Day 2019 is The International System of Units – Fundamentally better. This theme was chosen because on 16 November 2018, the General Conference on Weights and Measures agreed perhaps one of the most significant revisions to the International System of Units (the SI) since its inception. Research into new measurement methods, including those using quantum phenomena, underpin the change, which comes into force on today, 20 May 2019. Visit to the 2019 World Metrology Day Resource website <>

With the revision of the SI coming into force today, the BIPM webpages have been updated accordingly,, and the 9th edition of the SI Brochure is now official, released along with the Concise Summary, the updated Appendices and the updated Mises en Pratique of all the base units.


To celebrate IUPAC/IUPAC100 released a story titled “The New SI – The International System of units is getting a Makeover” by Ian Mills and Roberto Marquardt. (This story was first published in Chemistry International in January 2019 (CI 41(1), pp. 32-35;


Other members do celebrate as well ….

Brynn Hibbert (Div V) has a piece in The Conversation, titled “The way we define kilograms, metres, and seconds changes today.”

Roberto Marquardt (Div I) will present on May 21, at the Hungarian Academy of Sciences a lecture titled “IUPAC and the mole”. The lecture is part of a minisymposium titled “IUPAC and the seven stalwarts of science” and organized by Attila Császár.

Robert Belford (InChI) paper titled How Should General Chemistry Teaching Faculty Handle the New SI Base Unit Definitions’, co-authored with Peter Rusch, is open for comments on May 20.

others? let us know.

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