169 citations · 203 across the 10 of their papers we have counts for
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The failure of the Ehlers--Kundt conjecture in the impulsive case
Moriz L. Frauenberger, James D. E. Grant, Roland Steinbauer
In 1962, Ehlers and Kundt conjectured that plane waves are the only class of complete Ricci-flat~\emph{pp}-waves, i.e.\ metrics on of the form \[ ds^2=2du\,dv+dx^2+…
Timelike conjugate points in Lorentzian length spaces
James D. E. Grant, Michael Kunzinger, Argam Ohanyan +2
We study notions of conjugate points along timelike geodesics in the synthetic setting of Lorentzian (pre-)length spaces, inspired by earlier work for metric spaces by Shankar--Sor…
Generalizing the Penrose cut-and-paste method: Null shells with pressure and energy flux
Miguel Manzano, Argam Ohanyan, Roland Steinbauer
The cut-and-paste method is a procedure for constructing null thin shells by matching two regions of the same spacetime across a null hypersurface. Originally proposed by Penrose,…
Hawking's singularity theorem for Lipschitz Lorentzian metrics
Matteo Calisti, Melanie Graf, Eduardo Hafemann +2
We prove Hawking's singularity theorem for spacetime metrics of local Lipschitz regularity. The proof rests on (1) new estimates for the Ricci curvature of regularising smooth metr…