  The inertial collapse of two interacting and non-translating spherical
bubbles of equal size is considered. The exact analytic solution to the
nonlinear ordinary differential equation that governs the bubble radii during
collapse is first obtained via a slowly converging power series. An asymptotic
approximant is then constructed that accelerates convergence of the series and
imposes the asymptotic collapse behavior when the radii are small. The solution
generalizes the classical 1917 Rayleigh problem of single bubble collapse, as
this configuration is recovered when the distance between the bubble centers
far exceeds that of their radii.
