Professor Graham Machin, FREng
Head of Temperature Standards, NPL Fellow
National Physical Laboratory
UK Immediate Past President Institute of Measurement and Control
The implications of the kelvin redefinition
In November 2018 the General Conference of Weights and Measures (CGPM) made history by agreeing to redefine the international system of units (the SI) in terms of a defined set of fundamental constants. The kelvin from that time on was defined in terms of a fixed value of the Boltzmann constant. Starting from the previous definition of the kelvin, based on the triple point of water, this talk will explain how the kelvin was redefined including; the wording of the redefinition, the co-ordinated effort in determining low uncertainty values of the Boltzmann constant for the redefinition, and, the extensive preparations undertaken for introducing the mise en pratique for the definition of the kelvin (MeP-K-19) which will regulate the realisation and dissemination of the kelvin from the date of its redefinition. As the international thermometry community transitions to realisating and disseminating the redefined kelvin the short, medium and long term implications that the redefinition will have for the disciple of thermometry will be discussed.
Professor Graham Machin FREng, BSc (Hons), DPhil (Oxon), DSc, CPhys, CEng, FInstP, FInstMC GM is the science leader of the NPL Temperature and Humidity Group and an NPL Fellow. He has more than 30 years’ experience in thermometry research, published more than 220 technical papers and given numerous invited/keynote addresses. He is visiting Professor of Clinical Thermal Imaging (University of South Wales) and Distinguished Visiting Fellow (University of Valladolid, Spain). He represents the UK on the Consultative Committee of Thermometry (CCT) and IMEKO TC12, chairs the CCT working group for Noncontact thermometry and is an international invited expert on the CAS “very low temperature thermometry” project (2017-2022). He was President of the UK Institute of Measurement and Control (2018-2019), chair of the Euramet Technical Committee for Thermometry from (2014-2018) and served on the EPSRC Physical Sciences Strategic Advisory Team (2014-2017). GM was awarded the Institute of Measurement and Control (InstMC) Callendar medal in 2012 for “outstanding contributions to the art of temperature measurement”, Honorary Scientist of the Chinese Academy of Sciences (CAS) (2019) and elected Fellow of the Royal Academy of Engineering (2019). Current research interests are primary thermometry (acoustic, radiometric and especially all aspects of realising the redefined kelvin), radiation thermometry and thermal imaging, new thermocouples, sensor self-validation methods, reliable clinical thermometry (contact, non-contact and internal), reliable temperature (and other) measurements in hostile environments (especially aerospace and nuclear decommissioning).
He is project director of the “Realising the redefined kelvin” (Sep 2019) for EURAMET, a founder member of the “Body Temperature Initiative” which aims to improve clinical thermometry throughout the NHS and leads NPL’s metrology activity in nuclear decommissioning.