2 papers
math.DG2026
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…
math-ph2025
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+…