Klein-Gordon-Gleichung

$(\underset{t}{\overset{2}{\partial }}-\mathrm{\Delta }+m^2)\mathrm{\Psi }(\underset{\_}{x},t)=0$

$(◻+\frac{{\hslash }^2}{c^2}{m}^2)\mathrm{\Psi }(\underset{\_}{x},t)=0$