For readers who may have missed the news from Versailles amidst the current Brexit hullabaloo, we pass on a link to an article published by the BBC. This explains in laymen’s terms the long-awaited redefinition of the SI base unit of mass.
The BBC article may be found here:
A more technical explanation is provided by the publication Physics World:
We are grateful to one of our frequent contributors, Martin Vlietstra, who gave this explanation a few days ago of “Who does what” in the world of SI.
“The 26th CGPM is expected to agree the new definition on 16 November 2018. The draft resolution, which is being submitted by the CIPM can be seen at:
“For the record,
*The BIPM (“International Bureau of Weights and Measures” or, in French, “Bureau international des poids et mesures”) is the laboratory and associated staff located at Sevres close to Paris.
*The CIPM (“International Committee for Weights and Measures” or, in French, “Comité international des poids et mesures”) is an executive body consisting of 18 metrologists elected by the CGPM. The CIPM meets at least once a year and has executive oversight over the functioning of the Metre Convention and of the BIPM.
*The CGPM (“General Conference on Weights and Measures” or in French “Conférence générale des poids et mesures”) is a general assembly of representatives of all the countries that are party to the Metre Convention. It meets once every four to six years. This body has the final say on any changes to the definitions of SI.”
2 thoughts on “The kilogram rejuvenated”
For more than 130 years, the definition of the kilogram has been the mass of a cylinder made of a platinum iridium alloy, referred to as the International Prototype Kilogram (IPK). The cylinder was one of 40 similar standard kilograms cast in Britain by Johnson, Matthey & Co.
The new definition is in terms of a physical property of nature known as Planck’s constant. For its practical realisation, the new definition again relies on pioneering work done by British science.
British physicist Bryan Peter Kibble (1938 – 2016) was responsible for the development of the Kibble balance, an improved version of the current balance, which is the device that will be used in the practical realisation of the new definition of the kilogram.
Further to Metric Views’ recent article on the Bank of England’s request for nominations of British scientists to be considered for celebration on the new £50 note, Bryan Kibble, inventor of the device that will realise the new definition of the SI unit of mass, is certainly another worthy, and topical, candidate.
This is what happens when you use imperial: