## Differential Geometry Seminar: High frequency limits in general relativity

Seminar | November 13 | 1-2 p.m. | 891 Evans Hall

Jonathan Luk, Stanford

Department of Mathematics

It is known in the physics literature that "high-frequency weak limits" of solutions to the Einstein vacuum equations are not necessarily vacuum solutions, but may have a non-trivial stress-energy-momentum tensor, which can be viewed physically as “effective matter fields” arising from back-reaction of high frequency gravitational waves. A conjecture that can be found in the physics literature is that these limits are solutions to the Einstein-massless Vlasov system. We discuss a recent construction where the limiting matter field represents a finite number of families of null dust propagating in different directions (which can be viewed formally as a (singular) limit of the Einstein-massless Vlasov system). This is a joint work with C. Huneau (Grenoble).

rbamler@berkeley.edu