(November 17, 1717 – October 29, 1783)
A child prodigy who later matured into one of the most prominent geniuses of the 18th century, Jean le Rond d’Alembert earned his bachelor’s degree in law, and showed early interests in medicine and philosophy before embracing mathematics. At just 21 years old, he studied Charles-René Reynaud’s L’analyse Démontrée and rectified the errors he found there. He later projected Fluid Mechanics, made in-depth analyses of Refraction, and focused on them in his publication titled Mémoire sur la réfraction des corps solides. His contemporary, Alexis-Claude Clairaut, was impressed by this; and would later correspond with him as he (D’Alembert) devised math techniques with which he polished Isaac Newton’s Laws of Motion. His expertise in Fluid Dynamics enabled him to conjure a general math solution for one-dimensional wave equation. This solution is known as D’Alembert’s Formula, while wave equation is often referred to as D’Alembert’s Equation. He was also the first person to aver what is now called Cauchy-Riemann Equations (which Leonhard Euler, Augustin-Louis Cauchy and Bernhard Riemann later rediscovered successively). The same goes for Fundamental Theorem of Algebra (which French speakers call D’Alembert-Gauss Theorem, because D’Alembert was the first person to prove it, whereas Carl Friedrich Gauss later updated the proof with a more rigorous version). As one of 18th century’s leading scientists, Jean le Rond d’Alembert made many discoveries, doled-out publications, mentored several scholars, and helped launch the careers of both Joseph-Louis Lagrange and Pierre-Simon Laplace. A series of concepts and theorems are named in his honor.