A French mathematician, physicist and writer often credited to be one of the first female scientists, Èmilie was born 17 December 1706 in Paris to a father of lesser nobility. She grew up around learned men and her father, who had the position of the Principal Secretary and Introducer of Ambassadors to King Louis XIV, held a weekly salon where many well-respected writers and scientists were invited. During her life Émilie was a famous and respected figure in France. Her works were published in several countries and translated to German and Italian; her ideas discussed in the most important journals of the era, such as the Encyclopédie of Diderot and D’Alembert. She was active from the 1730s until her early death in 1749.
Unfortunately, she is most known for being Voltaire’s mistress. But she was a great scientist and thinker in her own right; which is one of the many reasons why I wanted to write something about her. I hope I made her justice.
As a child, Èmilie, got a good education. Along with her brothers she learned fencing, riding, gymnastics and at twelve years of age she spoke Latin, Italian, Greek and German. She became fascinated by science and math at a young age and her father, encouraging her pursuits of knowledge, arranged for her to talk about astronomy with Fontenelle, the secretary of the French Académie des Sciences and an acquaintance of theirs, when she was as young as ten! It is unknown and disputed whether her mother was so happy about her education, with some sources siting that she wanted to send her to a convent; while others depict her as encouraging.
Èmilie had a flair for gambling and when she was a teenager she used her mathematical skills to devise highly successful strategies. She wanted to get money so she could buy books! In 1725, when she was eighteen, she married the Marquis Florent-Claude du Chastellet-Lomont, like most of nobility, this marriage was arranged. After giving birth to three children the couple decided to separate and she reentered society and resumed her mathematical studies in 1733. It was accepted for both men and women to have lovers during this age in France and she had three before she met Voltaire, the lover through which she has found most of her fame.
Her first teacher back in society became the mathematician, astronomer and physicist Pierre de Maupertuis, a member of the Academy of Sciences and student of Johann Bernouilli, as well as a follower of Newton’s ideas. Mathematics wasn’t de Maupertuis forte so in 1735 Du Châtelet turned to Alexis Clairaut for further mathematical training. Clairaut was a mathematical prodigy best known for Clairaut’s equation and Clairaut’s theorem.
After meeting, and striking up a friendship, with Voltaire around 1733, she invited Voltaire to live with her at her rural residence in Cirey-sur-Blaise, Haute-Marne, and they became life partners. At that estate she studied physics and mathematics, as well as publishing scientific articles and translations. The years she spent with Voltaire at her estate were some of the most productive of her life. They worked hard and well together, and she helped with Voltaire’s Elements de la philospohie de Newton (1736), but without being given attribution.
One of her most famous own works were her Dissertation su la nature et la propagation du feu, which she submitted to Academie des Sciences in 1737 for the Grand Prix. She did not win but it was published in 1744, and she was the first woman to ever get this honor. Her work is based around her research of fire, and she describes, among other things, what will later be known as infrared light.
Her second publication was Institutions de physique (Lessons in Physics, published 1740). It was presented as a walkthrough of new ideas in science and philosophy for her thirteen-year-old son, in which she, among other things, discussed the nature of space and time and the understanding of natural phenomena associated with gravity. She explains and sought to reconcile ideas from leading thinkers at the time, such as doctrines by Descartes, Leibniz and Newton.
Emilie clarified the concepts of energy and energy conservation in one of her most important experiments. She followed an experiment by Dutch physicist Willem ‘s Gravesande where she dropped heavy lead balls into a bed of clay, where the results suggested that energy was proportional to mv2, contrasting with the direct proportionate mv, as had earlier been described by Newton and Voltaire. This publication honored her a spot as a member of the academy of science in Bologna in 1746.
The same year as her early death she finished one of her most renown works, the translation of Newton’s Principia, with her own comments, to French. An incomplete edition of her work appeared in 1756, and in 1759 the full publication was published; arranged through her friend and old teacher Clairaut. Her translation contains her conclusions around mechanics and energy principles and is, to this day, the French standard-translation of this work and the only complete French translation.
She published a book Discours sur le Bonheur (Discourse on happiness), written 1746, where she defends her love for sex and gambling as well as for studying and the desire for knowledge. Émilie was a strong advocate for women’s education and in the preface of her translation of The fable of the bees, she argues that society prevents women from becoming prominent in the arts and sciences. Voltaire was known to have said that ‘du Châtelet was a great man whose only fault was that she had been born a woman’.
She passed away aged 42 after becoming pregnant with the poet Jean Francois de Saint-Lambert, dying six days after giving birth due to an embolism. At her deathbed was her husband, her lover and Voltaire.