Just about everybody has heard of Isaac Newton, who figured out a lot of stuff that’s pretty basic to modern science and engineering. But just because Newton came up with his his principles and observations didn’t mean that everybody simply said “Oh, yes, that’s a better way to understand the universe.” It’s science, after all, and that means ideas, even Newton’s, have to be tested and his results replicated.
One of the most prominent scientists who helped validate Newton’s work was Alexis Clairaut, who was born May 13, 1713 in Paris. Among other things, he helped validate Newton’s theory of the exact size and shape of the Earth (it’s not exactly a sphere; it’s slightly flattened at the poles due to its spin).
Clairaut’s parents had twenty children, but it was the 1700s and only a few of them survived. He did, obviously, and was a child prodigy. He started calculus when he was 10, and at 12 wrote a mathematical paper about four geometrical curves he discovered. It was a pretty good paper; he was invited to read it in front of the Académie française. Then at 16 he published a paper about Tortuous Curves that got him admitted into the Royal Academy of Sciences — they waived their age limit for him.
Clairaut got a lot of attention from being a young genius, and it probably didn’t do him any good. At an early age he got used to the 18th-century equivalent of a jet-set lifestyle, and as his friend Charles Bossut wrote, “He was focused with dining and with evenings, coupled with a lively taste for women, and seeking to make his pleasures into his day to day work, he lost rest, health, and finally life at the age of fifty-two.” Even with all his high living, though, Clairaut continued making major contributions to math and science.
He joined an expedition to Lapland intended to validate Newton’s theory that the Earth had an ellipsoid shape. Although he started out skeptical of the idea, the expeditions measurements, along with calculations and new formulas he himself contributed, the theory turned out to be correct. Clairaut’s theorem is still around, and it’s one of the products of the expedition.
He was always eager to encourage students in math and geometry, and in 1741 published Éléments de Géométrie, a textbook that made geometry much more accessible. Some of the theories and methods from that text are still used.
You may have heard of the contemporary book and movie The Three-Body Problem. Clairault was one of the first (after Newton, who came up with it) to work on the problem. He even solved it, although his equations only give approximate answers. In the process he came up with a technique still used today to depict “orbital precession.” If you’ve seen an animation of the moon (or, for that matter, the ISS) orbiting the earth that shows each orbit proceeding along a slightly different path, that’s orbital precession. He did some other work in astronomy, including the first accurate measurements of the size and distance of Venus, and the path of Haley’s Comet.
Clairaut is not a household name on the order of Newton, but in math and geometry there are equations, theorems, and a “relation” that bear his name. He may have been the first to organize computation in such a way that he was able to divide a problem (the orbit of Haley’s Comet) among three people including himself, each computing a different aspect of the problem and combining the results later. It’s a very early example of a common computer programming technique. In fact, since the word “computer” meant “people” at the time, it really was computer programming. You can read more about Clairaut here, although it’s in French.
