Matt Visser

TL;DR: In this article, the authors provided further generalizations of the Buchdahl-Bondi bound by placing a number of constraints on the interior geometry (the metric components), on the local acceleration due to gravity, on various combinations of the internal density and pressure profiles and on the internal compactness 2m(r)/r of static fluid spheres.

TL;DR: In this paper, the authors construct a model that shares the key features of the Mazur-Mottola scenario and which is sufficiently simple for a full dynamical analysis, and find that there are some physically reasonable equations of state for the transition layer that lead to stability.

TL;DR: In this paper, it was shown that superluminal travel, potentially caused by the tipping over of light cones in Einstein gravity, is always associated with violations of the null energy condition (NEC), and that any object travelling within the lightcones of the weak gravitational field is similarly delayed with respect to the minimum traversal time possible in the background Minkowski geometry.

TL;DR: In this paper, a cosmographic analysis of the Friedmann-Lemaitre-Robertson-Walker (FLRW) class of cosmological models has been performed using supernova data and information about galactic structure.

TL;DR: In this paper, a spherically symmetric thin-shell traversable wormhole using the ''cut-and-paste'' technique was constructed, and the stability of the wormhole was analyzed.