Gabrielle Émilie Le Tonnelier de Breteuil, Marquise du Châtelet (; 17 December 1706 – 10 September 1749) was a French mathematician and physicist.
Her most recognized achievement is her philosophical magnum opus, Institutions de Physique (Paris, 1740, first edition; Foundations of Physics). She then revised the text substantially for a second edition with the slightly modified title Institutions physiques (Paris, 1742). It circulated widely, generated heated debates, and was translated into German and Italian in 1743. The Institutions covers a wide range of topics, including the principles of knowledge, the existence of God, hypotheses, space, time, matter and the forces of nature. Several chapters treat Newton's theory of universal gravity and associated phenomena. Later in life, she translated into French, and wrote an extensive commentary on, Isaac Newton's Philosophiæ Naturalis Principia Mathematica. The text, published posthumously in 1756, is still considered the standard French translation to this day.
Du Châtelet participated in the famous vis viva debate, concerning the best way to measure the force of a body and the best means of thinking about conservation principles. Posthumously, her ideas were represented prominently in the most famous text of the French Enlightenment, the Encyclopédie of Denis Diderot and Jean le Rond d'Alembert, first published shortly after du Châtelet's death.
She is also known as the intellectual collaborator with and romantic partner of Voltaire. In the two centuries since her death, numerous biographies, books, and plays have been written about her life and work. In the early twenty-first century, her life and ideas have generated renewed interest.
Early life Émilie du Châtelet was born Gabrielle Émilie Le Tonnelier de Breteuil in Paris, in the Kingdom of France, on 17 December 1706. She was the only daughter among six children of Louis Nicolas le Tonnelier de Breteuil and Gabrielle Anne de Froulay. Her father was a member of the lesser nobility and served at the court of Louis XIV as Principal Secretary and Introducer of Ambassadors.
Her brothers included René-Alexandre Le Tonnelier de Breteuil, Charles-Auguste Le Tonnelier de Breteuil and . Two other brothers died young. Du Châtelet also had an older paternal half-sister, Michelle, born in 1686.
Her father held a weekly salon at the family home, where writers and scientists were among the guests. When Louis XIV died in 1715, her father retired from his court position, and the family remained in Paris during the rest of du Châtelet's childhood.
Education
Du Châtelet's early education is not well documented, and accounts of it contain considerable uncertainty.
Her father, Louis Nicolas le Tonnelier de Breteuil, arranged for Bernard Le Bovier de Fontenelle, the permanent secretary of the French Académie des Sciences, to discuss astronomy with her when she was ten. Accounts differ about the role of her mother, Gabrielle Anne de Froulay, in her education. Some sources state that she opposed her daughter's intellectual interests, while others indicate that she encouraged du Châtelet to question accepted claims.
Her father arranged training in fencing and riding and later brought tutors to the family home. By the age of twelve, she was fluent in Latin, Italian, Greek and German, and she later translated Greek and Latin plays and philosophy into French. She also studied mathematics, literature and science. Du Châtelet danced, played the harpsichord, sang opera and acted. As a teenager, she used mathematical strategies in gambling when she needed money to buy books.
In 1733, aged 26, du Châtelet resumed her mathematical studies. She initially studied algebra and calculus with Pierre Louis Moreau de Maupertuis, a French mathematician and member of the Académie des Sciences. By 1735, she was studying with Alexis Clairaut, a French mathematician known for Clairaut's equation and Clairaut's theorem.
Du Châtelet also sought access to the intellectual life of Paris. At the Café Gradot, where men gathered for intellectual discussions, she was ejected when she attempted to join one of her teachers. She returned wearing men's clothing and was admitted.
Du Châtelet later corresponded with Johann II Bernoulli and Leonhard Euler, both Swiss mathematicians.
Relationships and children
Florent-Claude du Chastellet-Lomont On 12 June 1725, she married the Marquis Florent-Claude du Chastellet-Lomont (1695–1765).The Lomont suffix indicates the branch of the du Chastellet family; another such branch was the du Chastellet-Clemont. Her marriage conferred the title of Marquise du Chastellet.The spelling Châtelet (replacing the s by a circumflex over the a) was introduced by Voltaire, and has now become standard. () Like many marriages among the nobility, theirs was arranged. As a wedding gift, her 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-four.
Émilie du Châtelet and the Marquis Florent-Claude du Chastellet-Lomont had three children: Françoise-Gabrielle-Pauline (1726–1754), married in 1743 to Alfonso Carafa, Duca di Montenero (1713–1760), Louis Marie Florent (1727–1793), and Victor-Esprit (1733–1734). Victor-Esprit died as an infant in late summer 1734, likely the last Sunday in August. On 4 September 1749 Émilie du Châtelet gave birth to Stanislas-Adélaïde du Châtelet, daughter of Jean François de Saint-Lambert. She died as a toddler in Lunéville on 6 May 1751.Smith, D. W. "Nouveaux regards sur la brève rencontre entre Mme Du Châtelet et Saint-Lambert." In The Enterprise of Enlightenment. A Tribute to David Williams from his friends. Terry Pratt and David McCallam (eds.). Oxford, Berne, etc.: Peter Lang, 2004, pp. 329–343. See also Anne Soprani, ed., Mme Du Châtelet, Lettres d'amour au marquis de Saint-Lambert, Paris, 1997.
After bearing three children, Émilie, Marquise du Châtelet, considered her marital responsibilities fulfilled and reached an agreement with her husband to live separate lives while still maintaining one household.
Voltaire
Du Châtelet may have known the French writer and philosopher Voltaire during her childhood through the salons held by her father, which Voltaire attended. Voltaire later dated their first meeting to 1729, after his return from England. Their romantic relationship began in 1733, when du Châtelet was 26, after she returned to society following the birth of her third child. Du Châtelet remained married to Florent-Claude du Chastellet-Lomont, while her relationship with Voltaire continued until her death 16 years later.
In 1734, when du Châtelet was 27, Voltaire left Paris after his Letters on the English brought the threat of arrest and established himself at the Château de Cirey, the du Châtelet family estate in Haute-Marne in northeastern France. Cirey became a home for both du Châtelet and Voltaire and the main setting for their intellectual collaboration. The château was remodelled to include a laboratory with scientific instruments for their experiments.
Du Châtelet and Voltaire worked closely together at Cirey and shared an interest in the work of the English mathematician and physicist Isaac Newton. Du Châtelet's mathematical work with Pierre Louis Moreau de Maupertuis exceeded Voltaire's mathematical abilities. Scholars have identified significant contributions by du Châtelet, particularly to the more technical material, in Voltaire's Elements of the Philosophy of Newton, published in 1738, although the extent of her contribution to the work is uncertain. Voltaire addressed the work to du Châtelet in both verse and prose dedications, praising her knowledge of the subjects it discussed.
Saint-Lambert and fourth child A new relationship began late in du Châtelet's life. In 1748, aged 41, she became involved with Jean François de Saint-Lambert, a French poet and military officer, during a stay at Lunéville in the Duchy of Lorraine. Saint-Lambert belonged to the court of Stanisław Leszczyński, the former king of Poland and then Duke of Lorraine. Du Châtelet remained close to Voltaire, who accompanied her during her stays at Lunéville in 1748 and 1749.
Du Châtelet became pregnant by Saint-Lambert more than 16 years after the birth of her previous child. At the age of 42, she feared that she would not survive another childbirth and expressed her concern in her correspondence. She nevertheless continued working intensively on her French translation and commentary on Newton's Principia Mathematica, his major work on mathematics and physics. By January 1749 she had completed a preface to the work, and in May she was devoting most of her time to it while working with the French mathematician Alexis Clairaut.
On 4 September 1749, du Châtelet gave birth at Lunéville to her fourth child, a daughter named Stanislas-Adélaïde. Du Châtelet died there at about 1 a.m. on 10 September, aged 42, six days after giving birth, with Saint-Lambert present. Her daughter survived her by less than two years, dying in Lunéville on 6 May 1751.
Correspondence
Seventy-six surviving letters from du Châtelet to Pierre Louis Moreau de Maupertuis, a French mathematician and natural philosopher who taught her mathematics, date from 1734 to 1744. In her early letters to Maupertuis, du Châtelet discussed her mathematical studies and sought his advice. Their correspondence later covered subjects including Newtonian gravity, the properties of matter, free will, the vis viva debate and the ideas of the German mathematician and philosopher Gottfried Wilhelm Leibniz.
Du Châtelet also corresponded with mathematicians and scientists elsewhere in Europe. They included the French mathematician Alexis Clairaut, the Swiss mathematicians Leonhard Euler and Johann II Bernoulli, and the French mathematician and physicist François Jacquier. She also exchanged letters with Frederick II, king of Prussia and a patron of the arts and sciences. In May 1739, Frederick had a work by the German philosopher Christian Wolff translated into French and sent to du Châtelet at the Château de Cirey. Du Châtelet later sent Frederick an advance copy of her Institutions de Physique.
Du Châtelet continued corresponding with other mathematicians while working on her translation and commentary on the English mathematician and physicist Isaac Newton's Principia. Her correspondence with Johann II Bernoulli, a Swiss mathematician and professor at the University of Basel, continued until shortly before her death in 1749.
Publications and works
Dissertation sur la nature et la propagation du feu In 1737, when du Châtelet was 30, the Royal Academy of Sciences in Paris announced its 1738 prize competition, seeking an explanation of what fire was and how it spread. The Academy was a major scientific institution in 18th-century Europe. Women could attend its activities as members of the audience but could not participate in the institution on equal terms with its male members. Du Châtelet began investigating the subject while Voltaire, her partner and intellectual collaborator, was preparing his own entry at the Château de Cirey in northeastern France. She initially worked with him but came to disagree with several of his ideas about fire. Without telling Voltaire, she conducted her own work and prepared a separate entry for the competition.