Milestone in the history of science for SI-system

Fri, 25/01/2019

Unique moment in the history of science for SI-system 

In December, Professor Geoffrey Boulton from the School of GeoSciences, stepped down as President of the International Science Council’s Committee on Data for Science and Technology (CODATA) after the announcement of a high point of its 50-year history, completion of the re-definition of the values of the fundamental constants in the International System of Units (SI-system).  The re-definition was adopted in November 2018 by the General Conference on Weights and Measures, which meets at Versailles every four years. This event is a unique moment in the history of science, replacing values derived from measurement, with their attendant errors, by precise values derived from fundamental laws, which will now remain stable “for all time.” The process began 50 years ago with the definition of the second by means of atomic clocks, the definition of the metre from the speed of light thirty years ago, and now the definition of the kilogram, together with Planck's constant, the Avogadro constant, the Boltzmann constant, and the charge of the electron.  Geoffrey commented that “scientists should recognise the magnitude and significance of this 50-year effort, and applaud not only the members of the current CODATA Task Group that completed it, but all their predecessors since 1969".

Does the re-definition have practical value?

In a high-tech world where length subdivision does not end with nanometres and nor time subdivision with femtoseconds, the technical openness of the new SI is a huge bonus for all future progress in accuracy and precision; for example, in developing quantum technologies, enhancing diagnostic capabilities in the medical sector, improving the efficiency of energy harvesting or the analytical methods used in climate research. Precise measurement (metrology) has a long history. Four thousand years ago in the area of the Aegean Sea, the dominant trade route between Arabia-Asia and Europe, the reputation and influence of major trading cities depended on trustworthy weights and measures. One of the few crimes for which death was the penalty was cheating on these measures.  

Geoffrey has now been appointed to the Governing Board of the International Science Council, the senior international representative body for science, in which the natural and social sciences are integrated, much as in principle they are in the School. It is the recognised representative body for science at the United Nations, and is developing a new strategy to act as “the global voice for science” in an era where, though science is needed more than ever, there is probably more reluctance to listen to its voice.

Related links

Professor Geoffrey Boulton - staff profile

International Science Council’s Committee on Data for Science and Technology (CODATA) 

International Science Council

L to R: Professor Geoffrey Boulton; A replica of Le Grand K, the international weight that defines a kilogram; and the new base units of the SI.
L to R: Professor Geoffrey Boulton; A replica of Le Grand K, the international weight that defines a kilogram; and the new base units of the SI.