The hypothesis that all nature is in principle explicable by the laws of theoretical physics celestial and terrestrial mechanics and subject to experimental tests.
Pierre Simon Laplace (1749-1827) made major contributions to theoretical physics and celestial mechanics. In their time he and Adrien-Marie Legendre (1752-1833) were the outstanding figures in these fields, often developing each other’s ideas. Laplace lived through tumultuous times in France, held public office under several regimes, was appointed a Count of the Empire, later a Marquis, and in 1916 elected one of the Forty Immortals of the Academic francaise. He is said to have discussed astronomy with Napoleon Bonaparte on the held of battle. He published both mathematical and explanatory books on celestial mechanics and on the theory of probability. His work on probability laid the foundation for all subsequent work in the subject.