Le laboratoire épistolaire dans les oeuvres scientifiques de la marquise du Châtelet

In the eighteenth century, three camps of scientific thought appeared within the French scientific community: the Cartesians, the Newtonians, and the Leibnizians. According to the accepted physics argued by Fontenelle, Descartes, Malebranche, and Mairan, momentum, not force, was the essential quantity of motion. While Newtonians and Leibnizians agreed upon the significance of gravity and force, they bitterly disagreed with respect to momentum as the essential measurement of force. According to Newton, momentum and gravity were the main type of forces essential to movement; as with Cartesian mechanics, Newtonian momentum was given by the product of the mass and velocity. For philosophical and scientific reasons, Leibniz favored the vis viva, or “kinetic and potential forces,” the modern conservation of energy, as the essential quantity. Despite the support of experimental evidence, French Newtonians failed to convince the Cartesian establishment, and fewer scientists accepted the Leibnizian system. This heated debate spread from the most esoteric mathematical circles to the French educated public through the essays by notable personalities such as Moreau de Maupertuis, Voltaire, and the Marquise Gabrielle-Emilie du Châtelet. Scholars have traditionally published or written little about Gabrielle-Emilie du Châtelet outside of her associations with Voltaire, due to her few formal publications. Recently, the historical community has started to review her contributions--as both a scientist and as a translator--to eighteenth-century mechanics. In collaboration with eminent mathematicians Jean Bernoulli, Maupertuis, Alexis-Claude Clairaut, and Leonard Euler, she successfully argued the scientific validities of Newtonian and Leibnizian mechanics by adapting her ideas into the first French calculus textbooks and by working toward the modern concept of the energy conservation law. Like many eighteenth-century philosophers, Du Châtelet primarily used the letter both privately and publicly to challenge and to explore. The series of letters between 1737-1741 used numerous rhetorical tactics to construct and formulate a series of image-based and logical arguments to support the vis viva or the forces vives. Through constructing these “thought experiments” on paper, she successfully facilitated the spread of Newtonian ideas, sparked and persuaded in scientific debate, and unified Newtonian and Leibnizian theories into classical physics