Émilie du Châtelet

Gabrielle Émilie Le Tonnelier de Breteuil, Marquise du Châtelet was a French natural philosopher and mathematician from the early 1730s until her death due to complications during childbirth in 1749. Her most recognized achievement is her translation of and commentary on Isaac Newton's 1687 book Principia containing basic laws of physics. The translation, published posthumously in 1756, is still considered the standard French translation today. Her commentary includes a contribution to Newtonian mechanics—the postulate of an additional conservation law for total energy, of which kinetic energy of motion is one element. This led to her conceptualization of energy as such, and to derive its quantitative relationships to the mass and velocity of an object. Her philosophical magnum opus, Institutions de Physique, circulated widely, generated heated debates, and was republished and translated into several other languages within two years of its original publication.