Gabrielle Émilie Le Tonnelier de Breteuil, marquise du Châtelet (17 December 1706, Paris – 10 September 1749, Lunéville) was a French mathematician, physicist, and author during the Age of Enlightenment. Her crowning achievement is considered to be her translation and commentary on Isaac Newton’s work Principia Mathematica. The translation, published ten years after her death in 1759, is still considered the standard French translation.
Voltaire, one of her lovers, declared in a letter to his friend King Frederick II of Prussia that du Châtelet was “a great man whose only fault was being a woman”.
The first part of this fascinating video is all about Emile Du Chatelet and really is worth watching – Deskarati –
Du Châtelet was born on 17 December 1706 in Paris, the only daughter of six children. Three brothers lived to adulthood: René-Alexandre (b. 1698), Charles-Auguste (b. 1701), and Elisabeth-Théodore (b. 1710). Her eldest brother, René-Alexandre, died in 1720, and the next brother, Charles-Auguste, died in 1731. However, her younger brother, Elisabeth-Théodore, lived to a successful old age, becoming an abbé and eventually a bishop. Two other brothers died very young. Du Châtelet also had an illegitimate half-sister, Michelle, who was born of her father and Anne Bellinzani, an intelligent woman who was interested in astronomy and married to an important Parisian official.
Her father was Louis Nicolas le Tonnelier de Breteuil, a member of the lesser nobility. At the time of du Châtelet’s birth, her father held the position of the Principal Secretary and Introducer of Ambassadors to King Louis XIV. He held a weekly salon on Thursdays, to which well-respected writers and scientists were invited.
Du Châtelet’s education has been the subject of much speculation, but nothing is known with certainty.
Among their acquaintances was Fontenelle, the perpetual secretary of the French Académie des Sciences. Émilie’s father Louis-Nicolas, recognizing her early brilliance, arranged for Fontenelle to visit and talk about astronomy with her when she was 10 years old. Émilie’s mother, Gabrielle-Anne de Froulay, was brought up in a convent, at the time the predominant educational institution available to French girls and women. While some sources believe her mother did not approve of her intelligent daughter, or of her husband’s encouragement of Émilie’s intellectual curiosity, there are also other indications that her mother not only approved of du Châtelet’s early education, but actually encouraged her to vigorously question stated fact.
In either case, such encouragement would have been seen as unusual for parents of their time and status. When she was small, her father arranged training for her in physical activities such as fencing and riding, and as she grew older, he brought tutors to the house for her. As a result, by the age of twelve she was fluent in Latin, Italian, Greek and German; she was later to publish translations into French of Greek and Latin plays and philosophy. She received education in mathematics, literature, and science. Her mother Gabrielle-Anne was horrified at her progress and fought Louis-Nicolas at every step, once attempting to have Émilie sent to a convent.
Émilie also liked to dance, was a passable performer on the harpsichord, sang opera, and was an amateur actress. As a teenager, short of money for books, she used her mathematical skills to devise highly successful strategies for gambling.
On 12 June 1725, she married the Marquis Florent-Claude du Chastellet-Lomont. Her marriage conferred the title of Marquise du Chastellet. Like many marriages among the nobility, theirs was arranged. As a wedding gift, the husband was made governor of Semur-en-Auxois in Burgundy by his father; the recently married couple moved there at the end of September 1725. Du Châtelet was eighteen at the time, her husband thirty.
The Marquis Florent-Claude du Chastellet and Émilie du Châtelet had three children: Françoise Gabriel Pauline (born 30 June 1726), Louis Marie Florent (born 20 November 1727), and Victor-Esprit (born 11 April 1733). Victor-Esprit died as a toddler in late summer 1734, likely the last Sunday in August. In 1749 Émilie du Châtelet gave birth to Stanislas-Adélaïde Du Châtelet (daughter of Jean François de Saint-Lambert). She was born on 4 September 1749. The infant died in Lunéville on 6 May 1751.
Resumption of studies
In 1733, at the age of 26, du Châtelet resumed her mathematical studies. Initially, she was tutored in algebra and calculus by Moreau de Maupertuis, a member of the Academy of Sciences. Although mathematics was not his forte, Maupertuis had received a solid education from Johann Bernoulli, who also taught Leonhard Euler. By 1735, however, du Châtelet had turned for her mathematical training to Alexis Clairaut, a mathematical prodigy known best for Clairaut’s equation and Clairaut’s theorem.
Relationship with Voltaire
Du Châtelet and Voltaire may have met in her childhood at one of her father’s salons; Voltaire himself dates their meeting to 1729, when he returned from his exile in London. However, their friendship began in earnest in May 1733, upon her re-entering society after the birth of her third child.
Du Châtelet invited Voltaire to live in her country house at Cirey-sur-Blaise in Haute-Marne, northeastern France, and he became her long-time companion (under the eyes of her tolerant husband). There she studied physics and mathematics and published scientific articles and translations. To judge from Voltaire’s letters to friends and their commentaries on each other’s work, they lived together with great mutual liking and respect.
Final pregnancy and death
In May 1748, Du Châtelet began an affair with the poet Jean François de Saint-Lambert and became pregnant. In a letter to a friend, she confided her fears that she would not survive her pregnancy. On the night of 3 September 1749, she gave birth to a daughter, Stanislas-Adélaïde, but died a week later from a pulmonary embolism at the age of 42. Her daughter died roughly eighteen months later.
Scientific research and publications
Heat and light
In 1737, Châtelet published a paper entitled Dissertation sur la nature et la propagation du feu, based upon her research into the science of fire, that predicted what is today known as infrared radiation and the nature of light.
Institutions de Physique
Her book Institutions de Physique (“Lessons in Physics”) appeared in 1740; it was presented as a review of new ideas in science and philosophy to be studied by her thirteen-year-old son, but it incorporated and sought to reconcile complex ideas from the leading thinkers of the time.
Advocacy of kinetic energy
In it, she combined the theories of Gottfried Leibniz and the practical observations of Willem ‘s Gravesande to show that the energy of a moving object is proportional not to its velocity, as had previously been believed by Newton, Voltaire and others, but to the square of its velocity. (In classical physics, the correct formula is Ek = 1⁄2mv², where Ek is the kinetic energy of an object, m its mass and v its velocity.)
Translation and commentary on Newton’s Principia
In 1749, the year of her death, she completed the work regarded as her outstanding achievement: her translation into French, with her commentary, of Newton’s Principia Mathematica, including her derivation of the notion of conservation of energy from its principles of mechanics. Published ten years after her death, today du Châtelet’s translation of Principia Mathematica is still the standard translation of the work into French.