# Oliver Petersen: Unique continuation through compact Cauchy horizons

**Time: **
Thu 2023-10-05 10.30

**Location: **
3418, Lindstedtsvägen 25

**Language: **
English

**Participating: **
Oliver Petersen, KTH

In 1983, Moncrief and Isenberg conjectured that any compact Cauchy horizon in smooth vacuum spacetimes are Killing horizons, meaning that there is a Killing vector field in a neighbourhood of the horizon and in the globally hyperbolic region. The conjecture is now a theorem the non-degenerate case. A central ingredient in the proof is a unique continuation theorem for wave equations through non-degenerate compact Cauchy horizons. In this talk, the goal is to present the proof of this theorem and the necessary Carleman estimate in the simplest case possible: the Misner spacetime.

(Please note the unusual starting time.)