Alexis Clairaut
Who was Alexis Clairaut?
French mathematician, astronomer, and geophysicist (*1713 – †1765)
Biographical data adapted from Wikipedia’s article on Alexis Clairaut (CC BY-SA 4.0).
Biography
Alexis Claude Clairaut was born on May 13, 1713, in Paris, France, and passed away there on May 17, 1765. He was a leading figure in eighteenth-century Europe's scientific scene as a mathematician, astronomer, and geophysicist. His work was heavily influenced by Newton, and he spent much of his career verifying and expanding the principles Newton introduced in the Principia in 1687. Clairaut showed remarkable mathematical talent early on and joined the French Académie des Sciences at just eighteen, a rare recognition of ability during a time of intense scientific activity.
Clairaut's most famous work in geodesy came during the French geodetic expedition to Lapland in the 1730s. This expedition aimed to measure the length of a degree of arc along the meridian near the North Pole to determine whether the Earth was oblate, as Newton predicted, or prolate, as some of Descartes' followers thought. The measurements taken in Lapland, along with those near the equator in Peru, confirmed Newton's prediction of Earth's flattening at the poles. From this work, Clairaut developed what is now known as Clairaut's theorem, linking gravity variation at Earth's surface to the planet's shape and rotation speed.
In celestial mechanics, Clairaut made significant strides with the gravitational three-body problem, a tough issue in Newtonian physics. He was the first to provide a solid theoretical explanation for the Moon's orbit apsidal precession, a problem that had challenged many and was seen by some as a potential flaw in Newton's law of universal gravitation. His major work, the Théorie de la Lune published in 1752, offered a rigorous lunar theory valuable for navigation. He also wrote Recherches sur différents points importants du système du Monde, tackling other questions in gravitational astronomy.
In pure mathematics, Clairaut identified the symmetry of second-order partial derivatives, now a standard theorem in calculus. He also created Clairaut's equation, a type of first-order ordinary differential equation, and described Clairaut's relation in differential geometry, concerning geodesics on surfaces of revolution. His work on hydrostatic equilibrium connected his mathematical methods to significant physical problems, dealing with conditions for rotating fluid bodies to maintain a stable shape. In 1737, he was elected a Fellow of the Royal Society of London, showing the widespread respect for his work.
Clairaut spent his life in Paris, within the bustling scientific environment of the Académie des Sciences. He corresponded with leading mathematicians and astronomers across Europe and was seen as one of the prominent Newtonians of his time. His death in Paris on May 17, 1765, just after turning fifty-two, ended a career that had already brought about essential results in various science and mathematics areas.
Before Fame
Alexis Claude Clairaut came from a family with a strong math background. His father, Jean-Baptiste Clairaut, was a math teacher in Paris and nurtured Alexis’s talents early on. By ten, Clairaut was already studying calculus, and by twelve, he was reading papers on differential geometry to the Académie des Sciences. As a teenager, he presented original mathematical research, and his work on the geometry of space curves, published at eighteen, got him into the Académie in 1731.
Clairaut grew up during a time when French science was involved in a heated debate between Cartesian natural philosophy and Newtonian mechanics, which had been gaining popularity since the late 1600s. This lively period, combined with the Académie des Sciences’ goal to answer questions about Earth's shape, provided Clairaut with both the theoretical background and real-world problems to apply his impressive analytical skills. His early grasp of advanced math put him at the center of these discussions before he turned thirty.
Key Achievements
- Derived Clairaut's theorem relating surface gravity variation to the Earth's oblateness, confirmed by the Lapland geodetic expedition
- Produced the first satisfactory theoretical explanation of the apsidal precession of the Moon's orbit in the Théorie de la Lune (1752)
- Identified the symmetry of second-order mixed partial derivatives, a foundational result in calculus
- Formulated Clairaut's equation, a significant class of first-order ordinary differential equations
- Elected Fellow of the Royal Society in 1737 in recognition of his contributions to mathematics and natural philosophy
Did You Know?
- 01.Clairaut was admitted to the French Académie des Sciences at age eighteen, one of the youngest members ever accepted at that time.
- 02.He traveled to the Arctic Circle as part of the 1736–1737 Lapland expedition, enduring harsh polar conditions to take geodetic measurements that helped settle a major scientific controversy about the shape of the Earth.
- 03.His father taught him calculus before he was ten years old, and he was presenting mathematical papers to the Académie by the age of twelve.
- 04.Clairaut used his lunar theory to refine predictions of the return of Halley's Comet, helping to narrow the estimated date of its 1759 perihelion passage.
- 05.He died just four days after his fifty-second birthday, having published important work across geodesy, celestial mechanics, differential equations, and differential geometry within a single career.
Awards & Honors
| Award | Year | Details |
|---|---|---|
| Fellow of the Royal Society | 1737 | — |