World Metrology Day 2019

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Monday 20 May – World Metrology Day 2019 – is a day towards which I have been working for the last 14 years.

Back in 2005, my NPL colleagues Richard Rusby,  Jonathan Williams and I compiled a report on possible methods for measuring the Boltzmann constant. The aim of the measurement would be to obtain an estimate of the Boltzmann constant with sufficiently small uncertainty that the International Bureau of Weights and Measures (BIPM) would feel able to redefine what we mean by ‘one kelvin’ and ‘one degree Celsius’ in terms of this new estimate.

To cut a very very long story short, we succeeded. And tomorrow, that project comes to fruition.

Of course it wasn’t just me. Or even me and my immediate colleagues in the thermal team at NPL. We were helped by colleagues from across the laboratory, and from other institutions. Notably:

  • Cranfield University who manufactured the key component in the experiment,
  • The Korean National Laboratory KRISS and the Scottish Universities Environmental Research Council who helped with isotopic analysis of argon gas.
  • Colleagues helped us from:
    • LNE-CNAM in France,
    • INRIM in Italy,
    • NIST in the USA,
    • PTB in Germany,
    • CEM in Spain.

And I have probably missed an important institution or partner from this list because – frankly – it has been a long haul!

But even this list doesn’t include all the other teams involved in the wider kelvin re-definition project.

Several other institutions also sought to independently measure the Boltzmann constant using a range of different techniques and the value chosen by the International Bureau of Weights and Measures (BIPM) was the weighted average of estimates from this international effort.

In all, hundreds of scientists, engineers and technical staff around the world have supported this effort and I feel humbled to have had the opportunity to take part in a project of this scale.

And it is not just the kelvin, today three other units will also be be redefined – the mole, the ampere and the kilogram.

In this troubled world, it is a real comfort to me to feel the friendships built and professional relationships created during these last 14 years.

I think it shows that the International System of Units is a living international institution which really works; which brings people together from around the globe to make measurements better. The SI is an institution of which the whole world can feel proud.

Happy World Metrology Day 🙂

One Response to “World Metrology Day 2019”

  1. Andy Henson Says:

    Read the World Metrology Day message from the Directors of the BIPM and BIML. See the posters and events organized around the world to celebrate. Visit worldmetrogyday.org and celebrate the work of Michael and the many, many scientists like him around the world.

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