Talk:D'Alembert operator

Is is written $\Box$ or $\Box ^{2}$?

Is it equal to $\nabla ^{2}-{\frac {1}{c^{2}}}{\frac {\partial ^{2}}{\partial t^{2}}}$ or ${\frac {1}{c^{2}}}{\frac {\partial ^{2}}{\partial t^{2}}}-\nabla ^{2}$ ? Sources differ again.

It should be $\Delta :=(\mathrm {d} +\mathrm {d} ^{*})^{2}=|_{\mathbf {R} ^{3}}-\nabla ^{2}$ and $\Box$ is simply the Laplacian in Minkowski space. Of course signs are subject to conventions, but the square I have never seen before.MarSch 16:18, 18 Mar 2005 (UTC)