On Day Two of our special celebration of Lord Kelvin, some of the University of Glasgow’s leading academics discuss the importance of measurement in his work and how that legacy remains a force in today’s innovations

“When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind.” 

These are the words of Lord Kelvin, the University of Glasgow alumni whose commitment to measurement as a pathway to scientific knowledge and technological progress, continue to be relevant today in understanding the world around us.

As we celebrate his life and work on Day Two of our special commemoration of his bicentenary, we focus on how Lord Kelvin’s expertise in precision measurement and mathematics inspire and inform researchers at the University of Glasgow. These are scientists pushing the boundaries of what it is possible to measure and playing key roles in cutting-edge technologies, such as quantum optics and gravitational wave detection. 

Much of Lord Kelvin’s living legacy is due, too, to his indomitable work ethic, as Professor Miles Padgett, Royal Society Research Professor and Kelvin Chair of Natural Philosophy explains.

“Kelvin is the first scientist I can think of who, in addition to doing all this fundamental research in thermodynamics and understanding temperature, actually rolled up his sleeves and applied his intellect to solve the real engineering problems of the day. He had fantastic research outputs but worked hard to ensure the societal impact of his research; he almost has more to show on the impact side. 

“He’s still exciting and much of his science relevant. More importantly, his attitude of ‘I am very smart but I also want to do work on things that are important and make a difference’ is a powerful message for researchers today.”

Prof Padgett believes one of Kelvin’s strengths lay in bringing together expertise, incisive measurements and the ability to invent things that were practical and worked.

“This attitude persists of being entrepreneurial, pragmatic and seeking knowledge. And perhaps that’s his true legacy. You’ve the Kelvin temperature scale, the tangible things, but the attitude is what’s really important.”

Prof Padgett and his research team certainly share that all-encompassing attitude in the way they cover all things optical, from the basic ways in which light behaves as it pushes and twists the world around us to the application of new optical techniques in imaging and sensing. 

As principal investigator of QuantIC, the UK hub for quantum imaging that brings together 120 full-time researchers in quantum technology across eight UK higher education partner institutions, he is involved with research that includes the development of a new form of endoscope the width of a human hair. 

“What did Kelvin’s transatlantic cable have to do with his great work on temperature? Absolutely nothing. On the other hand, he saw it as the problem that needed solving and applied his creativity to do so successfully. So, I didn’t set out to build a very, very, very thin endoscope. I learned about light, I learned about shaping light, I learned about optical fibres . . . then you see something that needs done and apply those skills to that problem in front of you. 

“Inspired by this use of deep scientific knowledge to drive practical solutions, my colleagues and I are now turning complex quantum science into technologies for healthcare, green energy and navigation. 

“We hope our efforts, like Kelvin’s, will lead to future innovations that improve lives and address global challenges.”

Lord Kelvin married many disciplines in his pursuit of knowledge and innovation

These challenges are not only global but daunting; thanks, however, to Kelvin’s inspirational lead, today’s scientists are making huge leaps, even if the steps are almost fantastically tiny – as Professor Sheila Rowan, director of the University’s Institute for Gravitational Research, explains.

“I’ve spent my career along with others in my institute working on designing and building instruments to detect gravitational waves. These are signals that come from colliding stars, black holes, far out in the universe, and they give us a different way to do astronomy – not through looking at light from the stars but from measuring gravitational signals. 

“These waves were a prediction by Einstein in 1916 but it took decades of development, the work of many people, to build instruments sensitive enough to make these first detections. Next year will be the 10th anniversary of the first detection in which Glasgow played a part. 

“That’s quite a story when you look at the work put in by many people over many years with many setbacks. For a long time people didn’t think it would be possible to make instruments sensitive enough to detect these tiny signals. Getting over those challenges, not giving up – that’s what Kelvin would have understood. He believed what he wanted to do in terms of the transatlantic telegraph cable was going to be possible. He didn’t give up,” says Prof Rowan, who holds the Chair of Natural Philosophy, the same position Kelvin held during his time at the University.  

“For me, it’s that persistence, married with interest in instrument building, that is vital. Lord Kelvin was a great believer in precision measurement but he also thought about how his work might be practically useful. 

“That’s something we see more and more in science now, even in the area I work in. It sounds esoteric; we’re doing a form of astronomy but we’re developing precise technology all the time. We are also thinking how this can be useful.

“Other research at my Institute looks at some of those spin-offs and how technology from our wave detectors can be useful. 

“The Institute is leading work to take some of that technology and build miniature gravity sensors that can measure local changes on the surface of the earth. 

“Why is that important? Well, you can do things like put multiple little instruments near volcanoes to measure magma flow and geophysical effects.

“So there are practical applications we are looking at from the spin-offs of our instrument building and technology. It’s a good exercise we all should do when we do science. We sometimes do it for fundamental reasons, but you know, we should always be thinking, how can this be useful? Is there an application there because some of these things can be revolutionary.”


GRAVITATIONAL astrophysics and cosmology may be topics that came long after Kelvin but there, too, is a strong link to the 19th century pioneer. 

“The real connection is abstract,” says Professor Martin Hendry, the University of Glasgow’s Clerk of Senate and Vice Principal, who worked as an astrophysicist in its School of Physics & Astronomy, where he also served as Head of School. 

“It’s firstly the idea of mathematics being something you can use to make quantitative predictions, even in areas where there isn’t currently the means of directly testing those predictions. We have this idealised picture of science as a virtuous circle where theoreticians come up with ideas and experimentalists test those ideas, and this helps refine the theory and so on. It’s great if that happens. But a lot of the time there’s a long lag between the ideas and the ability to test them. 

“That is true in spades when it comes to our gravitational wave work because Einstein basically predicted their existence before we had the technology capable of really measuring them. 

“So the spirit of Kelvin is manifest in these ways: the idea that theory can take the lead and guide you to fundamental truths, even if it takes a while before you can experimentally test them. But the key to doing the experimental testing is to develop incredibly precise measurement techniques. With regards to the gravitational wave discovery that’s ongoing, it’s not a case of, right, we’ve detected them now what’s next? 

“It’s about opening up a new window on how to study the universe in this new way. That I think is what Kelvin would’ve been fascinated by if he had lived long enough to see it.”

Professor Hendry was part of the team at the University’s Institute for Gravitational Research, which played a key role in the historic first direct detection of gravitational waves in 2015.

“Something that speaks to our gravitational wave work, although not personally, because I’m mainly on the theory analysis side, is that some of our research group are involved in translating precision measurement technology into useful things. 

“The kind of precision measurement and control techniques we need to operate in our wave detectors and move the mirrors by incredibly tiny amounts: our former colleague Stuart Reid was able to translate some of that technology into ‘nanokicking’, a viable technique to stimulate embryonic stem cell growth and is in the process of setting up a spin-out company to do this.”

“That’s a great example of where, just like Kelvin, you had the fundamental signs leading more or less in real time into practical applications. 

“We are inspired by the Kelvin example to do that. Thanks to Kelvin, these are all useful lessons we have in our toolkit.”

Dr Stephen J Watson, lecturer in the University of Glasgow’s School of Mathematics and Statistics, notes Kelvin profoundly shaped and influenced the scientific thought of his generation through his use of abstract mathematical analysis to uncover deep and abiding truths in the realms of science, engineering and materials science. 

Dr Stephen J Watson of the School of Mathematics & Statistics pays tribute to Kelvin’s lasting legacy

He says: “Driven by a desire to understand the laws of nature at their deepest level, he not only mastered the most sophisticated analysis methods of his time, but also created new mathematical tools and logical frameworks to unlock the mysteries of the great physical problems of his day: thermodynamics (the science of James Watt’s steam engine), 
electricity and magnetism, and the theory of light.

“The impact of his remarkable mathematical contributions are to be found throughout the science and engineering of the modern era. William Thomson’s seminal axiomatic formulation of the Second Law of Thermodynamics laid the cornerstone for the definitive formulation of the theory of equilibrium thermodynamics.

“Kelvin’s mathematical analysis of electricity and magnetism also inspired James Clerk Maxwell (Scotland’s other great 19th century scientist) to uncover the definitive theory of electro-magnetism, which lead to the transcendent proof that light is an electromagnetic wave!

“His dissipation principles governing non-equilibrium thermo-mechanical processes, and his discovery of associated reciprocal relations, also later found full-expression in the Nobel Prize winner Onsager’s 1931 work on such reciprocal relations: the significance and impact of which resonates to this day via the Principle of Maximal Dissipation. 

“He also made seminal contributions to the theory of crystal structure and equilibrium crystal growth through the Gibbs-Thomson equation, and thereby laid the foundations for the modern disciplines of materials and surface science that underpin the advanced materials and nano-scale technologies of today.”