In November 2018, the 26th General Conference on Weights and Measures will review the International System of Units (SI) of four of the seven base units namely kilogram, ampere, kelvin and mole by fixing the values of the Planck constant (h), the elementary charge (e), the Boltzmann constant (k) and the Avogadro constant (N_A). Upon approval, the redefined SI will be implemented worldwide starting from the following World Metrology Day which is on May 20, 2019.

The simultaneous redefinitions of four SI base units have never occurred in the history of the SI or even the Metre Convention. Obviously this will have significant impacts on the worldwide science and metrology community. On October 27 this year, the Metrology Symposium 2017 was held to introduce the latest development of this important event to the local testing and certification industry, as well as parties interested in metrology. The Symposium was jointly organised by the Government Laboratory (GL), the Hong Kong Council for Testing and Certification (HKCTC), the Open University of Hong Kong (OUHK) and the Standards and Calibration Laboratory (SCL) of the Innovation and Technology Commission (ITC).

The Symposium was attended by Dr Della Sin, Government Chemist of GL, Prof Albert Yu, Chairman of HKCTC, Ms Jane Lee, Secretary-General of HKCTC, Prof K C Ho, Dean of the School of Science and Technology of the OUHK, Mr Vincent Tang, the then Assistant Commissioner for Innovation and Technology (Infrastructure and Quality Services), and more than 200 participants from over 75 companies and organisations.

The plenary speech was delivered by Dr Della Sin on how metrology supports our daily life. Dr Sin explained the importance of metrology and introduced the global and local metrology infrastructures. Dr Sin retraced the history of development of metrology from the Metre Conventions in 1875, the adoption of the SI in 1960, to the upcoming redefinition of the four SI base units. Other speakers from the SCL and GL then presented details on the proposed redefinitions of the four SI base units. In the last presentation, one speaker reviewed the status of revision on another important document for the metrology community – “Guide to the Expression of Uncertainty in Measurement” (GUM). The participants actively engaged in discussion with the speakers on various topics of the Symposium at the question and answer session.