Pierre Simon de Laplace (1749 - 1827)

Pierre Simon de Laplace was a French mathematician and astronomer
who lived on the planet from 1749 to 1827. At the age of just 19, he
was appointed Professor of Mathematics in Paris. His research on the
eccentricities and inclinations of planetary motions helped prove their
stability. His papers on integral calculus discussed finite differences,
differential equations and varied subjects of astronomy, which gave rise
to the analysis of Spherical Harmonics. He described the nature of the
solar system in his "Exposition of the System of the World," through his
famous Nebular Hypothesis, which viewed the solar system as originating
from the contracting and cooling of large, flattened, and slowly rotating
clouds of incandescent gas. His acclaimed "Treatise on Celestial Mechanics,"
based partly on gravitational theory, further described the relationship
of the planets within our solar system. His Theory of Analytical Probabilites
helped us understand and develop systems of mathematical probabilites.

Laplace's most enduring contribution to mathematics is clearly the
differential operator, called the "Laplacian" in his honor. This fundemental
operator describes electrostatics, wave propagation, heat flow and has deep
generalizations to modern mathematical physics. The Laplacian of one is
zero, as illustrated by the equation below: