Pierre-Simon Laplace rose from humble beginnings in Normandy to become renowned in the fields of engineering, mathematics, statistics, physics, astronomy, and philosophy.  Traité de mécanique céleste was probably Laplace’s best-known contribution to mathematics and astronomy and is thought to be as important as Isaac Newton’s contribution in the previous century.  The first four volumes were published between 1798 and 1805, with a fifth and final volume appearing in 1825.

Laplace was born into a rural farming family but went to study mathematics in Paris.   As a mathematician, he lived in the world of the infinitesimal governed by differential equations.  In applying mathematics to physical problems, Laplace’s approach was to:

… establish that the phenomena of nature can be reduced in the last analysis to actions at a distance between molecule and molecule, and that the consideration of these actions must serve as the basis of the mathematical theory of these phenomena.

In later years he applied his ideas to a wide range of phenomena: e.g. probability theory as applied to physical observations, capillary action, refraction of light, speed of sound, heat transfer, and the dynamics and cooling of the Earth.

Laplace equation

Laplace and his assistant, Baron Siméon Denis Poisson (1781–1840), are probably familiar to every engineering student today because of the equations named after them involving the so-called Laplacian operator.  These equations have been applied to understanding a wide range of physical phenomena, including in recent times, the stresses that arise in a twisted shaft or beam.  Laplace also had thoughts about the origins of the universe and Professor Stephen Hawking (1942–2018) stated that Laplace had predicted what we now term ‘black holes’.