3 papers
math.DG2023
A conformal Hopf-Rinow theorem for semi-Riemannian spacetimes
Annegret Burtscher
The famous Hopf-Rinow Theorem states, amongst others, that a Riemannian manifold is metrically complete if and only if it is geodesically complete. The Clifton-Pohl torus fails to…
math.DG2021
Variations of Weyl's tube formula
Annegret Burtscher, Gert Heckman
In 1939 Weyl showed that the volume of spherical tubes around compact submanifolds M of Euclidean space depends solely on the induced Riemannian metric on M. Can this intrinsic nat…
math.AP2019
Initial data and black holes for matter models
Annegret Y. Burtscher
To observe the dynamic formation of black holes in general relativity, one essentially needs to prove that closed trapped surfaces form during evolution from initial data that do n…