On convergence of exterior solutions to radial Cauchy solutions for ${\square }_{1+3}U=0$

Helge Kristian Jenssen, Charis Tsikkou

Consider the Cauchy problem for the 3-d linear wave equation ${\square }_{1+3}U=0$ with radial initial data $U(0,x)=\Phi (x)=\varphi (|x|)$, $U_t(0,x)=\Psi (x)=\psi (|x|)$. A standard result gives that…