Spherical wave
= Spherical wave
{title2=$e^{\pm ikr}/r$}
For time dependence $e^{-i\omega t}$, the three-dimensional radial solutions $e^{ikr}/r$ and $e^{-ikr}/r$ describe outgoing and incoming <spherical waves> away from the origin. Their inverse-radius amplitudes make their flux through spheres independent of radius. They form the asymptotic radial ingredients of <partial-wave scattering>.