Description
Traversable wormholes provide a remarkable laboratory for probing the interplay between geometry, matter, stability, and causality in general relativity. Matt Visser has played a central role in transforming these objects from speculative constructions into precisely calculable geometries. After a brief historical introduction, we will focus on Matt’s thin-shell programme: cut-and-paste wormholes, Israel-Lanczos junction conditions, the localization and quantification of exotic matter, and the Poisson-Visser stability analysis. We will then discuss the geometric characterization of static and dynamical throats, chronology issues, generic thin shells and gravastars, and the more recent black-bounce programme, where regular black holes and traversable wormholes emerge within a common geometrical framework. The unifying theme is characteristic of Matt’s approach to physics: turning bold questions about spacetime into explicit calculations of geometry, exoticity, stability, and causal structure -- in short, “sculpting spacetimes” while keeping the physical interpretation of each geometrical construction fully explicit.