Wormholes in an Expanding Universe
This presentation explores a surprising theoretical result: traversable wormholes can exist inside closed, dust-filled cosmologies without requiring exotic matter. Using extended Lemaître–Tolman–Bondi solutions, the authors show that ordinary dust can support wormhole geometries that evolve with cosmological expansion and contraction. The wormhole throat exists only briefly, but the surrounding wormhole region persists throughout the full cosmic cycle. Numerical photon-propagation calculations confirm that such wormholes can be traversable under suitable conditions.Script
General relativity usually demands exotic matter to hold a wormhole open. This paper asks whether ordinary dust, evolving with cosmic expansion, can support a traversable wormhole inside a closed Friedmann universe.
The authors use Lemaître–Tolman–Bondi solutions, which describe spherically symmetric dust with radial inhomogeneity. A wormhole throat is defined as a regular minimum of the areal radius on a constant-time slice, requiring both the mass function F and the velocity function h to satisfy strict continuity conditions so the dust density remains finite.
The wormhole region is matched to closed Friedmann universes at boundary surfaces. The matching imposes continuity of the areal radius and the radial velocity function, embedding the wormhole into the cosmological expansion cycle.
Numerical integration of radial photon paths reveals that light can traverse the wormhole. Some photons cross the throat and escape into the external universe, while others encounter singularities. The throat itself exists only during a brief interval, much shorter than the full cosmic cycle.
The throat and the surrounding wormhole region operate on vastly different scales. A kilometer-sized throat can sit inside a wormhole region spanning hundreds of parsecs or more. Near the throat, densities can reach nuclear levels, but at the outer boundary the density drops below the cosmic mean, resembling a cosmological void.
Ordinary dust evolving with the cosmos can briefly open a traversable wormhole, offering a window between regions or even separate closed universes. To dive deeper into cosmological geometries like these, visit EmergentMind.com and create your own explainer videos.
