D'Alembert Operator Definition
noun
A differential operator which may be expressed as \partial_\mu \partial^\mu = \sum_{\mu = 0}^3 {\partial \over \partial x^\mu}{\partial \over \partial x_\mu}; it is the four-dimensional (Minkowski space ) equivalent of the three-dimensional Laplace operator .
Wiktionary
Origin of D'Alembert Operator
Named after Jean le Rond d'Alembert (1717-1783), a French mathematician, mechanician, physicist, philosopher, and music theorist.
From Wiktionary
