On the 200th anniversary of John Tyndall's birth, Sir Roland Jackson looks back at the life and work of the great natural philosopher.
2 August 2020 is the 200th birthday of the provocative Irish physicist John Tyndall.
Or is it?
2 August is certainly right, as Tyndall mentioned it often. But his records held in Dublin were destroyed in 1922 during the Irish Civil War, and he gave conflicting information about his age later in his life. So, happy birthday anyway, even if the actual year may have been 1822 or 1821. The great day will be celebrated in Carlow, near his birthplace of Leighlinbridge in an online event at 2pm.
Tyndall was professor of natural philosophy at the Royal Institution from 1853 until he retired in 1887. He worked with Michael Faraday, and took over as Superintendent of the House and Director of the Laboratory on Faraday’s death in 1867.
It is surprising that he is not better known. This is despite the existence of the Tyndall Centre for Climate Change Research, The Tyndall National Institute in Cork, The Pic Tyndall on the Matterhorn, and several Mount Tyndalls, Tyndall glaciers and Tyndall craters on the Moon and Mars. From that, one can see that he was both a significant scientist and a notable mountaineer.
It’s the Tyndall Centre that gives the clue to his best-known discovery. In 1859, Tyndall showed that gases including carbon dioxide and water vapour can absorb heat. His heat source was not the sun, but radiation from a copper cube containing boiling water. That makes it, in modern terms, longwave infrared radiation, like that radiated from the earth’s surface. The work of Fourier had shown that the earth’s temperature was higher than expected, which he put down to the atmosphere acting as an insulator. But no-one knew the explanation for what we now call the greenhouse effect.
What Tyndall did was to discover and explain its mechanism. He wrote: ‘Thus the atmosphere admits of the entrance of the solar heat; but checks its exit, and the result is a tendency to accumulate heat at the surface of the planet’. He realised that any change in the amount of water vapour or carbon dioxide in the atmosphere could change the climate. His work set a foundation for our understanding of climate change and meteorology.
Tyndall was not, however, the first to make the climate link. That prize goes to the American Eunice Foote, who showed in 1856 that carbon dioxide could absorb heat. She made the supposition that an increase in carbon dioxide would result in a warmer planet. It seems likely that Tyndall was not aware of her work.
But this is just one of a host of Tyndall’s discoveries, across disparate fields of physics and biology. He made his initial reputation in the abstruse topic of diamagnetism, the weak repulsion of substances by a magnet. Soon he was at work on understanding glacier structure and motion. After that came the work on the absorption of heat by gases, and then the action of light in causing chemical changes. In the process Tyndall explained why the sky is blue, through the preferential scattering of blue light. The ‘Tyndall effect’, of light scattering from colloids, is named after him. So too is ‘Tyndallization’, a bacteriological technique of sterilization, which Tyndall discovered when undertaking experiments alongside Louis Pasteur to support the germ theory of disease. That line of research led to the invention of a respirator for firefighters, though Tyndall never took out a patent. He committed himself to fundamental research, confident that others would generate useful applications.
For many years Tyndall acted as scientific adviser to the government on lighthouses around the British and Irish coasts. His research led to an understanding of how sound could be scattered in the atmosphere, and the design of better foghorns.
As a public intellectual, Tyndall’s was one of the loudest voices advocating a scientific explanation for the natural world and for life itself, a scientific naturalism. In this, religion and theology had no place. He gave the starkest statement of this position in his famous, indeed notorious, Belfast Address, as president of the British Association in 1874. In the Ulster Hall he thundered: ‘We claim, and we shall wrest from theology, the entire domain of cosmological theory. All schemes and systems which thus infringe upon the domain of science must, insofar as they do this, submit to its control, and relinquish all thought of controlling it’.
But he was never one to belittle the role of religion. Science, for him, provided reliable knowledge of the world. Religion met people’s emotional needs, a role he thought might eventually to be replaced by poetry.
He married in his 50s, but his beloved Louisa killed him by accident in 1893, giving him an overdose of the wrong medicine in the dark. She gathered huge amounts of material to write his biography but died 47 years later with it uncompleted. That is part of the reason he is not better known, but he also had the misfortune to die on the cusp of big new discoveries in physics such as quantum theory and relativity. In a sense he represented the past. It is time now to recognise and reinstate him as a major Irish scientist, mountaineer and public intellectual.
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