At the age of 16, Laplace entered Caen University to study theology. However, during his two years at the University of Caen, Laplace discovered his mathematical talents and his love of the subject. Consequently, he left Caen without taking his degree, and went to Paris. He took with him a letter of introduction to d'Alembert. Although Laplace was only 19 years old when he arrived in Paris he quickly impressed d'Alembert, so d'Alembert got him the job of professor of mathematics at the Ecole Militaire.
His approach to physics, attempting to explain everything from the forces acting locally between molecules, influenced physics greatly. In 1805, he wrote a study of pressure and density, astronomical refraction, barometric pressure and the transmission of gravity based on this new philosophy of physics. Laplace continued to apply his ideas of physics to other problems such as capillary action, double refraction, the velocity of sound, the theory of heat, and elastic fluids, and he wrote papers on all these subjects.
Laplace made many achievements in applied mathematics and astronomy, and their effects are still being felt today. Starting in 1773, he applied his mathematical talents to celestial mechanics problems. He made groundbreaking work in the orbital interactions between Saturn and Jupiter, lunar orbital motion, the shape of planetary bodies, tides, and the stability of the solar system.
Not only was Laplace adept at astronomy and mathematics, he was also cunning at politics. He managed to stay in the good graces of rulers through the French Revolution, the Napoleonic era, and the return of the French monarchy. In addition to his scientific honors, Laplace was appointed to the French Senate by Napoleon in 1799. Following Napoleon’s fall, Laplace was given the rank of Marquis by the returning French monarchy, which is why he is also known as Marquis de Laplace.
Little is known of his early life other than that his father was a farmer because the snobbish Laplace, after he became famous, did not like to speak of his humble origins. Rich neighbors, it is said, recognized his talent and helped finance his education, first at Caen and later at the military school in Beaumont. Through the efforts of the famous physicist d'Alembert, who was impressed by his abilities and his effrontery, Laplace became a professor of mathematics in Paris at age 20.
He was an opportunist, shifting his political allegiance as required so that his career successfully spanned three regimes in revolutionary France - the republic, the empire of Napoleon, and the Bourbon restoration. Napoleon made him a count and Louis XVIII made him a marquis. His mathematical abilities, however, were genuine, inspiring the great mathematician Simeon Poisson to label him the Isaac Newton of France
Pierre-Simon Laplace (1749-1827) was among the most influential scientists in all history. His career was important for his technical contributions to exact science, for the philosophical point of view he developed in the presentation of his work, and for the part he took in forming the modern scientific disciplines.
His views on the origin of the solar system, the material theory of heat, and the determinism of the universe, while recognized as innovative, seemed to fit naturally with the classical doctrines. As a result, he was pictured as a scientific sage valued more for his magisterial syntheses than for his pioneering achievements.
Pierre Simon was the fourth of five children. An older sister, Marie Anne, was born in mid-June 1745. Twins Jacques Pierre and Julie Marguerite were baptized on 12 January 1748, but died three days later. A year after Pierre Simon came Olivier, on 1 May 1750. We generally know little about the siblings and their children, none of whom figure in the scientist's later life.
"We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect, which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movement of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future, just like the past, would be present before its eyes."
- Pierre Simon Laplace, A Philosophical Essay on Probabilities