Using an eigenfunction expansion in to solve for G ( r, , t| r0 , 0 , 0) that satisfies \u0012 \u0013 (r r0 ) ( 0 ) it 1 G 1 2G 2G = r + 2 e , r > 0, 0 < < r r r r 2 t2 r G G = 0, = 0, r 0 =0 = G outgoing as r Some guy refer me this is monochromatic wave in upper half plane, could any one solve this Green's function? 1