John William Strutt, 3rd Baron Rayleigh (1842–1919), was one of the most important British physicists of the late 19th and early 20th century: Cavendish Professor of Physics at Cambridge (1879–1884, as successor to James Clerk Maxwell), Nobel Prize in Physics 1904 for the discovery of the noble gas argon (jointly with William Ramsay), originator of Rayleigh scattering – the physical explanation for why the sky is blue. Master of Trinity College Cambridge 1908–1919, Order of Merit 1905, President of the Royal Society 1905–1908. In the same year that he died, he was also President of the Society for Psychical Research – and in January 1919 he delivered an address that summed up decades of careful psi research.
Who was Lord Rayleigh?
Rayleigh was born in 1842 at Langford Grove (Essex) as the eldest son of the English noble Strutt family. He went up to Trinity College Cambridge and in 1865 was Senior Wrangler – the mathematically strongest position in his year. In 1873 he inherited the title of 3rd Baron Rayleigh and the family seat at Terling Place, Essex, where he set up a private laboratory. Most of his scientific work was done there, often without formal academic affiliation.
In 1879 Cambridge appointed him the second Cavendish Professor of Physics – as successor to James Clerk Maxwell and predecessor of Joseph John Thomson (later the discoverer of the electron). This chair is one of the three or four most important physics positions in the world in the 19th/20th century. After Cambridge he returned to Terling, but in 1908 was called back to Cambridge as Master of Trinity College – a position he held until his death in 1919.
Scientific achievements
Rayleigh's scientific output is exceptionally broad. The main points:
- Rayleigh scattering (1871). The explanation of why sunlight in the atmosphere scatters off air molecules in such a way that short (blue) wavelengths are deflected much more strongly than long (red) ones. Hence the blue sky and the red sunset. One of the most elegant derivations in classical optics.
- Discovery of argon (1894/95, with William Ramsay). During precision measurements of the density of nitrogen, Rayleigh noticed a tiny systematic difference – nitrogen obtained from air was slightly denser than chemically produced nitrogen. From that followed the discovery of a previously unknown noble gas. Nobel Prize in Physics 1904; Ramsay received the Nobel Prize in Chemistry the same year.
- Rayleigh-Jeans law. The classical description of black-body radiation, the failure of which at high frequencies (the "ultraviolet catastrophe") led Max Planck to the quantum hypothesis in 1900.
- Theory of sound. His two-volume work The Theory of Sound (1877/78) remained the standard work in acoustics worldwide for over 50 years.
- Numerous works on hydrodynamics, capillarity, viscosity, diffraction, photometry.
In other words: Rayleigh stands undisputed in the canon of physics. Anyone who would dismiss him as "credulous" has to explain why the Royal Society elected him president (1905–08), why the Swedish Academy awarded him the Nobel Prize, and why Cambridge made him Master of Trinity.
Joining the SPR – the Cambridge connection
The Society for Psychical Research was founded in 1882 in Cambridge, very much in the orbit of Trinity College. Founding members were Henry Sidgwick (Knightbridge Professor of Moral Philosophy at Cambridge), Frederic Myers, Edmund Gurney – a high-calibre, very academic circle. Sidgwick was a personal acquaintance of Rayleigh; both moved in the same Cambridge intellectual world.
An important biographical point: Rayleigh's wife was Evelyn Balfour, sister of Arthur James Balfour – the later British Prime Minister (1902–05). Balfour himself was President of the SPR in 1893. Through him and through the Sidgwicks, Rayleigh was embedded in the centre of that Anglican-academic elite that institutionalised psi research in Cambridge. This constellation – a Prime Minister, a Cavendish Professor and a Knightbridge philosopher as SPR Presidents within one generation – would today be an argument in itself in any debate about science.
Eusapia Palladino and the Cambridge sittings, 1895
In August and September 1895 Sidgwick and Myers brought the Italian medium Eusapia Palladino to Cambridge, to Frederic Myers's house at Selwyn Gardens. Over several weeks around 20 séances were held, with changing participants from the SPR circle – including Oliver Lodge, Richard Hodgson and the physicist Joseph John Thomson.
The Cambridge sittings ended dramatically: Hodgson, one of the SPR's sharpest sceptics, documented several cases in which Palladino had demonstrably cheated under loose hand and foot control. The SPR then officially distanced itself. Lodge, who had been very positive earlier in Italy, was disappointed. Rayleigh as Cavendish Professor and SPR Council member was involved in the discussions; whether he personally attended individual Cambridge sittings is not unambiguously documented in the sources. His style was in any case that of a methodologically extremely cautious observer – not an enthusiast.
Methodological caution – Rayleigh's position
Rayleigh's basic stance can be well reconstructed from his published contributions in the Proceedings of the SPR and from the biographical sources (above all his son R. J. Strutt's 1924 biography). Three points are characteristic:
- Distinction between telepathy and physical phenomena. Rayleigh considered the statistical evidence for telepathy (from the Gurney-Myers-Podmore studies and later replications) more serious than the physical materialisation and table-levitation findings. That is a differentiated, not a blanket position.
- Do not generalise fraud findings. That mediums like Palladino were caught cheating was for Rayleigh not an argument to reject the whole field. He insisted that methodological rigour be applied to the individual case, not to the category.
- Tolerate not-knowing. Rayleigh was willing to let phenomena stand as "not explicable with current physics", without committing himself to an explanation – neither sceptical nor spiritualistic. That is methodologically mature, and rare in the scientific establishment to this day.
The 1919 presidential address
On 29 January 1919 Rayleigh delivered as President of the SPR his inaugural address before the annual meeting in London (published in the Proceedings of the SPR, Vol. 30, 1919/20). It was his late summing-up: Rayleigh was 76 at the time, had been involved with the SPR since its early years, and knew – as we see in hindsight – that not much time remained. He died five months later, on 30 June 1919.
In the address Rayleigh drew no groundbreaking conclusion. But he did confirm that after decades of engagement, phenomena had remained which he could not explain away with all the means of his own physics – particularly in the field of telepathy, and in individual cases of physical manifestations. At the same time he warned against over-eagerness and against the conflation of "remarkable phenomenon" with "proven survival hypothesis". The task of the SPR was to continue working the field with the same care that physics itself applies.
"I have learned much in this society – not least, that there are appearances I cannot explain with the means of my own science, and that it would be unscientific to take them for unreal on that account."
— Paraphrase of Lord Rayleigh's position in his SPR presidential address of 29 January 1919 (Proceedings of the SPR, Vol. 30)
What remains
- Maximum scientific reputation. Nobel Prize Physics 1904, RS President, Cavendish Professor, Master of Trinity. Rayleigh is the highest scientifically decorated person ever to have served as SPR President.
- A differentiated position. Unlike Crookes or Lodge, Rayleigh never publicly committed himself to a survival hypothesis. But neither did he claim that the field was methodologically closed. This "third position" – take seriously without committing – is the methodologically most mature of the three.
- Embedded in an elite. Through his wife (sister of Prime Minister Balfour) and his Cambridge colleagues, Rayleigh was part of an aristocratic-academic stratum that treated psi research as a serious scientific field. This constellation has been largely lost in the 20th century – an argument we develop in our piece on Mediumship and Power.
- A late summing-up. The 1919 presidential address is Rayleigh's last major public statement on the subject – five months before his death. It was a methodological commission, not a personal confession of faith.
Rayleigh belongs in the historical line we are tracing on this site: Kepler, Crookes, the Curies, Lodge, Jung, Pauli, Einstein, Rhine, PEAR. Among them he is the most cautious – and therefore the one whose voice is hardest to refute today.
Sources
- Lord Rayleigh: Presidential Address. Proceedings of the Society for Psychical Research, Vol. 30, London 1919/20.
- Lord Rayleigh: Scientific Papers. 6 volumes, Cambridge University Press 1899–1920.
- Lord Rayleigh: The Theory of Sound. 2 volumes, Macmillan, London 1877/78 (several editions).
- Robert John Strutt (4th Baron Rayleigh): Life of John William Strutt, Third Baron Rayleigh. Edward Arnold, London 1924 (son's biography, the standard source).
- Robert Bruce Lindsay: Lord Rayleigh — The Man and His Work. Pergamon, Oxford 1970.
- Alan Gauld: The Founders of Psychical Research. Routledge & Kegan Paul, London 1968 – on the Cambridge SPR founding phase.