Abstract :
Dear Readers, Besides being a world-class metrologist, Michael de Podesta is passionate about the wider issue of creating a scientifically savvy population able to form sensible views about topics such as global warming, nuclear energy, depletion of global resources and so on which will greatly affect succeeding generations. He contributes to general awareness about the scientific principles needed to consider these problems via the U.K.\´s National Physical Laboratory "Protons for Breakfast" educational course, supplemented by his on-going internet blog. Bryan Kibble News about the forthcoming 2018 re-definition of the International System of Units ( SI) usually focuses on the resolution of the long-standing \´kilogram problem.\´ But, there will also be significant changes in the definition of other units and indeed, in the very concept of a \´unit.\´ Here, I would like to tell you about the proposed changes in the definition of the unit of temperature, the kelvin (K). Outside of the various National Measurement Institutes, such as the USA\´s NIST or the UK\´s NPL where I work, the number of industrial or scientific users calling for a redefinition of the kelvin is probably zero. Nonetheless, our current definition is linked to historical anomalies, and I hope to convince you that the re-definition makes a lot of sense. The SI underpins a vast measurement infrastructure: it is a truly great and often underappreciated human achievement. But all great structures have foundations, and all foundations need occasional maintenance. As anyone who has ever undertaken such work on their house will attest, this work is expensive and slow, and in the end there is nothing to \´show\´ for it except confidence that the building will not subside in the future. Let\´s look at why this work on the current kelvin definition is desirable and how the under-pinning work will support the \´new\´ kelvin.
