D'alembert operator Updated +Created
D'alembert operator in Einstein notation Updated +Created
Given the function :
the operator can be written in Planck units as:
often written without function arguments as:
Note how this looks just like the Laplacian in Einstein notation, since the D'alembert operator is just a generalization of the laplace operator to Minkowski space.
Pseudometric space Updated +Created
Metric space but where the distance between two distinct points can be zero.
Notable example: Minkowski space.