Written in the notation of partial derivatives, the d'Alembertian  square ^2 in a flat spacetime is defined by

  square ^2=del ^2-1/(c^2)(partial^2)/(partialt^2),

where c is the speed of light.

The operator usually called the d'Alembertian is also the Laplacian on a flat manifold of Lorentzian signature.

See also

Gradient Four-Vector, Harmonic Coordinates, Laplacian, Wave Equation

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Cite this as:

Weisstein, Eric W. "d'Alembertian." From MathWorld--A Wolfram Web Resource.

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