Collisions of false vacuum bubbles in cylindrical symmetry

We explore the collision of two cylindrical bubbles in classical general relativity with a scalar field stress-energy tensor. Inside each bubble the field rests at a local minimum of the potential with non-negative energy density. Outside the field rests at zero potential, the global minimum. The calculation resolves the connection from the inner de-Sitter region to the asymptotically flat Minkowski spacetime. We choose initial conditions such that the two bubbles collide and study the full nonlinear evolution by means of a two-dimensional numerical simulation of Einstein's equations. The collision generates a strongly interacting region with spatially varying fields and potentials. These circumstances promote dynamical exploration of the potential's landscape. No horizon is present and the scalar curvature invariants eventually diverge. We speculate that Schwarzschild-like horizons will encompass only part of the complicated, interesting regions of spacetime in the analogous case of colliding spherical bubbles.