  We study bubble universe collisions in the ultrarelativistic limit with the
new feature of allowing for nontrivial curvature in field space. We establish a
simple geometrical interpretation of such collisions in terms of a double
family of field profiles whose tangent vector fields stand in mutual parallel
transport. This provides a generalization of the well-known flat field space
limit of the free passage approximation. We investigate the limits of this
approximation and illustrate our analytical results with a numerical
simulations.
