Which one for the first thinkers to form Free will in antiquity was also well-known for formulation of an atomic theory of the universe?
Democritus Democritus ( ; Greek: Δημόκριτος , "Dēmókritos", meaning "chosen of the people"; c. 460 – c. 370 BC ) was an influential Ancient Greek pre-Socratic philosopher primarily remembered today for his formulation of an atomic theory of the universe.
Émilie du Châtelet Gabrielle Émilie Le Tonnelier de Breteuil, Marquise Du Châtelet (] ; 17 December 1706  – 10 September 1749) was a French natural philosopher, mathematician, physicist, and author during the early 1730s until her untimely death due to childbirth in 1749. Her most recognized achievement is her translation of and commentary on Isaac Newton's book "Principia" containing basic laws of physics. The translation, published posthumously in 1759, is still considered the standard French translation today. Her commentary includes a profound contribution to Newtonian mechanics—the postulate of an additional conservation law for total energy, of which kinetic energy of motion is one element.