Lucasian Chair.org

"He had the true spirit of a philosopher, more anxious to see science advance than that he should have priority in advancement. Alexander Macfarlane

Sir George Gabriel Stokes (1819-1903), born in Ireland, followed Joshua King in the Lucasian Chair. Stokes restored the dignity and integrity of the Chair to the level of its first two professors, Barrow and Newton. Although great men such as Sir George Airy and Charles Babbage held the Chair in the first part of the century, Airy held it for only two years and Babbage for all his achievements, neither resided at Cambridge nor delivered any lectures. Stokes held the Chair for fifty-four years, longer than any other scholar. Stokes came to Cambridge for his undergraduate years in 1837, the year that Queen Victoria took the throne, and never left.¹ Although proficient in several fields, Stokes elected to lecture on optics while holding the Lucasian Chair.

Stokes's basic field was physics, but his most important contribution was in fluid mechanics when, in 1845, he described the motion of viscous fluids. These equations are known today as the Navier-Stokes equations, and are considered fundamental equations. Stokes independently discovered the equations twenty years after Claude Navier had arrived at them, but Stokes used continuous flow, not molecular flow, as did Navier, so the credit for the method is shared.² As described by his contemporaries, Stokes was modest, dedicated, hard working and religious. Administrative work and teaching slowed his productivity, but he pursued these activities out of a sense of duty. The Royal Society of London benefited for many years from his service as secretary (1854-1885) and president (1885-1890). He guided the publication of their journals, Transactions and Proceedings, with a skilled hand. He was awarded their Rumford Medal in 1852 and their Copley Medal in 1893 and was president of the British Association for the Advancement of Science in 1869. Other awards included the Gauss Medal (1877), the Arago (1899) and the Helmholtz (1901). The French made him a Foreign Associate of the French Institute and the Germans made him a Knight of the Prussian Order Pour le Merite.³ An active member of the Cambridge Philosophical Society he was its president from 1869 to 1902. He was also a member of Parliament, representing the university from 1887 to 1891. From 1888-89 he was a royal commissioner for the reform of the University of London. Stokes gave the Burnett Lectures in the winters of 1883, 1884 and 1885 in Aberdeen, Scotland, on the nature of light.⁴ In 1891 and 1893, he delivered the Gifford lectures at the University of Edinburgh, Scotland, on the topic of natural theology.⁵

As an undergraduate Stokes attended Pembroke College, graduating in 1841 as senior wrangler and winner of the Smith's Prize. He was elected as a fellow the same year.⁶ He spent virtually his entire adult life at Cambridge, sixty-six years. He was elected Master of Pembroke College in 1902 the year before he died.⁷ His contribution to Cambridge was as great as his contribution to science. He raised the status of the Lucasian Chair after his immediate predecessor had occupied it without producing any memorable achievements. "... Prof. Stokes is regarded as the principal founder of the Cambridge school of mathematical physicists, one of the main glories of the British mathematicians of the nineteenth century ..."⁸ Certainly the men who followed Stokes as the Lucasian professors were of the highest caliber.

Stokes was unselfish in his attitudes toward scientific development. The awards and honors so important to scientists are acquired through public acclaim of credit for discoveries. To share this may mean sharing the honors or missing out completely. However, "Prof. Stokes not only lectured to the junior members of the University and advised the senior members in questions of applied mathematics, but he was also very helpful to scientists in general."⁹ It appears that all who benefitted from the generosity of Stokes shared the honors with him.

Stokes was an applied mathematician working in physics, in the tradition of the work that had been done by professors of the Lucasian Chair before him. And like many of his predecessors, he branched out into other areas while continuing to develop his own speciality. He contributed in many scientific areas, but his best known work was in fluid mechanics, also known as hydrodynamics or hydrokinetics, by virtue of the Navier-Stokes equations describing viscosity. He treated elasticity and wave motion in solids and fluids exhaustively. As a result, he made important contributions to mathematics as he developed techniques and tools to assist him in his work.

In 1843, he published a paper which spelled out his theory of viscosity of fluids and the famous equations for its influence in fluid motion.¹⁰ second paper, published in 1850, used the contents of the earlier paper to solve several nontrivial problems concerning oscillations of a globe and cylinder in fluids and the motion of a viscous fluid around these geometrical shapes. These solutions had immediate applications to the study of ocean waves and of electrolysis, and long-term applications to the design of aircraft and automobiles. The 1850 paper also reported Stokes' Law, describing the terminal velocity of objects falling through liquids.

Other discoveries were named for him, for example, the Stokes Theorem (1854) reduced selected surface integrals to line integrals. The theorem "...relates a surface integral taken over a surface to a line integral taken around the boundary curve of the surface."¹¹ It is a generalization of an earlier theorem known as Green's Theorem. In 1847, Stokes figured out the uniform convergence of a series. Kelvin noted that Stokes had done such outstanding work in the areas of light and optics, that he could be considered great based on this work alone.¹² One of Stokes' major discoveries was fluorescence, explained in his paper in 1852. Stokes published the Dynamical Theory of Diffraction in 1849, supporting the wave theory of light.

The work that Stokes did that did not get as much attention as his work on fluids was on the ether. During the 1800's, the ether was still not really questioned as the medium for light to travel in as the waves traveled in air or water. There was contention over the specific makeup and characteristics in which Stokes participated. His work on the aether as an elastic solid provided the basis for the modern day understanding of elastic solids. Even though the aether is no longer accepted as a reality, the understanding of the solid Stokes believed composed it, has withstood the test of time.

Stokes was a religious man. He delivered the Gifford lecture series on natural theology and then published them.¹³ In this book he details his view of God and his relationship to the world. He was conservative in his views, mirroring the existing religious establishment. He was president of the Victoria Institute, which had been founded in the 1860s in response to the scientific movement exemplified by Charles Darwin's Origin of Species.¹⁴ Furthermore, he was vice president of the Evangelical British and Foreign Bible Society and active in the Church Missionary Society. He was outspoken on religious issues, speaking often in public and writing extensively to the clergy. As Stokes was a man who thought deeply and analytically, it is not surprising that his views contained beliefs from opposing camps of thought. For example, although he was an establishment believer, he embraced ideas of the Evangelical movement, known for emotional attachment to religion devoid of the sophisticated theological positions of high-church Anglicanism.

Several major issues occupied Stokes in his religious thinking. One that bothered him from childhood was the problem of eternal suffering. He believed that because of his propensity for mathematics at an early age, the thought of infinity had far more meaning to him than to other children. He was unable to accept that God would make children suffer forever. In his more developed arguments he proposed that Christ died so that we would not have to be punished forever. The principle of conditional immortality was accepted by him and many others.

The next principle was the tripartite nature of man. Stokes proposed, as well, that man consisted of body, soul and spirit, rather than the dual nature consisting of only body and soul. The dual nature of man was first put forth by Plato, not the Bible, according to Stokes, and he believed that the concept was propagated by theologians and philosophers who did not go back to the source. For Stokes, the spirit was the element that provided the life essence to the body and it survived death. The difficulty for him was explaining the difference between spirit and soul.¹⁵ But he also believed that the source for this knowledge was revelation and not reason.

A third part of his religious thought was directionalism, a concept he created to oppose materialism. A problem had arisen from the new theory of evolution: it seemed that nonthinking, nonliving matter was bound to living matter by the laws of the conservation of energy. Everything was bound together so that every event had a cause and an effect. There was no free will, and no need for God or moral behavior. Directionalism stated that life was not energy, but rather directed energy, so it was above the conservation of energy laws. These were furious debates at the time providing a pivotal point in the history of the relationship of science and religion.¹⁶

Footnotes

1. Lord Rayleigh, "Sir George Gabriel Stokes, Bart. 1819-1903," Proceedings of the Royal Society of London 75 (1905): 200.
2. L. Rosenhead, Laminar Boundary Layers (Oxford: Oxford University Press, 1963), 121.
3. Rayleigh, 215.
4. Macfarlane, 102
5. Macfarlane, 104.
6. Rayleigh, 200.
7. Rayleigh, 215.
8. Macfarlane, 96.
9. Macfarlane, 98.
10. Lord Kelvin ed., Mathematical and Physical Papers 6vols. (Cambridge: Cambridge University Press, 1882-1911), 6:340.
11. S. C. Malik, Mathematical Analysis (New York: John Wiley & Sons, 1984), 687.
12. Kelvin, 6:339.
13. Sir George Gabriel Stokes, Natural Theology. The Gifford Lectures delivered before the University of Edinburgh in 1891 (London: A. and C. Black, 1891).
14. David Wilson, "A physicist's alternative to materialism: the religious thought of George Gabriel Stokes," Victorian Studies 28 (Autumn 1984): 71.
15. D. Wilson, 84.
16. D. Wilson, 96.