There has been a subtle prejudice against intellect since time immemorial. This was never so true as it was for young women. A lady needed to only know how to smile, look pretty and keep a household. Anything further would make her a “bluestocking” and unattractive to men. Perish the thought! 18th century France was no exception as the nobility had a deep seated aversion to educating their daughters. However, from this unlikely source came one of the great mathematicians of the century.
Gabrielle Émilie le Tonnelier de Breteuil was born December 17, 1706 in Paris to Louis Nicolas le Tonnelier de Breteuil, a high ranking official of the court of Louis XIV. Young Émilie was educated at home as befit a young noble woman, and learned to speak six languages by the time she was twelve. Mathematics was where she really shined much to her mother’s dismay as well bred girls did not have interests in such matters. Luckily, her father encouraged Émilie and introduced her to prominent scientists he knew from court. Émilie used her talent at numbers in a more practical way as well. She had a flair for gambling, and like many gamblers used her knowledge of mathematics to improve her odds. Her winnings from her gambling adventures went to fund her interest in the math and sciences by buying books and laboratory equipment. Smart and practical. I like it.
Being a practical woman, Émilie knew she would be required to marry. At age 18, she accepted the proposal of Marquis Florent-Claude du Châtelet with her family’s consent. Marquis du Châtelet came from an old noble family from Lorraine and brought a title to the table but no money. He was thirty-four to Émilie’s eighteen, an arrangement that was not unusual for the time. For the first few years of the marriage, Émilie was forced to amuse herself with trips to Paris while running their household in Semur. During this time, she gave birth to daughter and two sons. Her interest in mathematics never waned, and she amused herself by reading and studying mathematics and philosophy. Émilie returned to Paris and began serious study of Rene Descartes’ analytical geometry with Pierre-Louis Moreau de Maupertuis and Alexis-Claude Clairaut. While her husband was away in the wars of the 1730s, Émilie spent her time studying. She insisted on the best tutors of the time, and this brought her into the orbit of Voltaire. At this time, Voltaire was the rock star of the scholarly world. The two were instantly smitten, and Voltaire became her constant companion for the next fifteen years. This was even after he began an affair with her young niece.
Together, Émilie and Voltaire renovated Châtelet country house with a large library of about 20,000 books, which rivaled the libraries of many universities at the time, and extensive laboratories for scientific experiments. Émilie was barred from many scientific societies and universities solely because she was a woman. To get around this, they held elaborate dinner parties and salons with noted scholars of the day so they could share knowledge and learn. In 1737, Émilie wrote a paper based on her experiments with light, heat and fire. Dissertation sur la nature et la propagation du feu was submitted to the French Academy of Sciences, and while it did not win the contest it was well received. In this paper, she anticipated the existence of infrared radiation as well as suggested the different colors of light carried different heating powers.
She and Voltaire worked together to coauthor a book on the work of Isaac Newton, which was controversial in France as the bias ran towards Cartesian philosophy. Although Voltaire’s name was the only one to appear on Elements of Newton’s Philosophy, he openly acknowledged her role in writing it. Striking out on her own in 1740, Émilie then wrote Foundations of Physics, in which she undertook the daunting task of integrating Newtonian, Cartesian and Leibnizian views of physics.
Throughout this study, Émilie was still active as a mother and running her household. At the age of 42, she found herself pregnant again. This time, the father was her lover, Jean-François de Saint-Lambert. Despite both of them having new lovers, she and Voltaire were still devoted to each other. With his help and the help of Saint-Lambert, Émilie was able to convince her husband the child she was carrying was his. A pregnancy at the age of 42 at that time was very dangerous, but Émilie did not slow down for an instant. She was in the middle of translating Newton’s Principia into French, and wanted to make sure that it was finished. This was not merely a translation, but included Émilie’s own notes, examples and clarifications. She worked 18 hours a day to finish this masterpiece. However, this took a serious toll on her health.
In September 1749, Émilie gave birth to a daughter. Voltaire describes the birth, “The little girl arrives while her mother was at her writing desk, scribbling some Newtonian theories, and the newly born baby was placed temporarily on a quarto volume of geometry, while her mother gathered together her papers and was put to bed.” However, Émilie died from a pulmonary embolism three days later and her infant daughter followed. Her seminal work, the translation of Principia was published ten years later in 1759 with a preface by Voltaire. Her earlier work, which was being circulated privately in Enlightenment circles was published later.
Voltaire said ““she lived a life at a full tilt like a spirited healthy child” The accident of her sex did not keep her from her love for life and mathematics.