(Paris 1 June 1796 – 24 August 1832)
Eldest son of Lazare Carnot, brother of Hippolyte. Physicist known as the founding father of thermodynamics.
After having attended Charlemagne High School, Sadi was received twenty-fourth at the École Polytechnique in 1812, at the age of sixteen. He graduated at the top of his class in Artillery. He fought against the Allies with the Polytechnicians’ Battalion during the defense of the Vincennes Fort in 1824.
As a candidate to join the General Staff in 1819, he was accepted with the rank of Lieutenant. He had achieved the rank of Captain in the Corps of Engineers by the time he left the army in 1828 to settle in Paris. He died there of cholera at the age of thirty-six. He had no heirs.
Sadi Carnot is known as the founder of thermodynamics. In 1824, he published at his own expense, Reflections on the Motive Power of Fire and on Machines Fitted to Develop this Power. It is in this book—of less than a hundred-and-twenty pages, with a limited printing of only six hundred copies—that he founded what we call today the Second Law of Thermodynamics or Carnot’s Principle.
He also discovered the first principal, that of energy conservation, before the end of his life, as is shown in his essays published posthumously in 1878.