Using h to denote the gravitational potential, the Lagrangian for the graviton has terms proportional to h, h cubed, and h times this operation applied to h. This operation's associated Green's function equals a delta (15[2])function of “t minus r over c” divided by 4 pi r. In the Lorenz gauge, applying this operation to the vector potential gives negative mu-nought times the (15[1])current (15[1])density. This (*) Lorentz-invariant operation is applied to a function to give zero in (-5[1])the most compact representation of the (10[1])wave (10[1])equation. It is defined as one over (10[1])c squared (-5[1])times (10[1])the second time derivative, minus the square of the (-5[1])gradient. Either a box or “box (-5[2])squared” symbolizes, for 10 points, what operation named for a French (0[1])physicist, the analogue (10[2])of (10[2])the (10[1])Laplacian in Minkowski space? ■END■