The globally trapped future: a fate for black holes and wormholes

Abstract

We present a novel framework that can generate any spherically symmetric metric (at least locally) through a coupled scalar-electromagnetic system. We then specialize to a class of non-stationary spacetimes characterized by analytically tractable global causal structure and trapping horizons, which is particularly suited for investigating the evolution of black holes and wormholes. Within this framework, we find that the fate of spacetime can be categorized into three distinct classes: those without a globally trapped future; those without a globally trapped future but containing bounded, Cauchy-foliated trapped regions; and those with a future that becomes completely trapped. The evolution of a geometrically Schwarzschild-like black hole and a horizonless wormhole demonstrates these possible fates, thus revealing the globally trapped outcome as a novel theoretical possibility. Finally, we propose that a regular black hole may contain an unattainable minimal throat—a minimal-radius throat that is causally unreachable—and refer to it henceforth as the asymptotic throat.