A wormhole that hides inside a black hole — solved exactly

Using a type of field borrowed from string theory, two physicists built exact solutions where a black hole's central singularity is replaced by a 'bounce' into a wormhole throat. One solution behaves like a Schwarzschild black hole with a cosmological constant at large distances; the other produces exotic matter only near the bounce, turning normal near the horizon — a trick previously requiring modified gravity. Both geometries are everywhere finite, suggesting singularity-free black holes are possible within standard general relativity.