Last week, I had the opportunity to give two lectures (totaling 3 hours) on black-hole perturbation theory in Alessandra Buonanno’s course on gravitational waves at the AEI. The course is offered to students at Humboldt University, the University of Maryland, and the AEI. The (excellent) PhD student Aldo Gamboa conducted a tutorial session.
What did we cover? We went over some general ideas about perturbation theory and quasinormal modes, computed quasinormal frequencies using the WKB approximation (and discussed their relation with null geodesics in the eikonal/geometrical optics limit), learned how to do metric perturbations of static spherically symmetric spacetimes (and derived the famous Regge–Wheeler equation), and, finally (phew!), had an overview of the Newman–Penrose formalism and the Teukolsky equation.
It was quite intense, as you can tell from the above!
This was my second time as a guest lecturer in Alessandra’s course. The first time was in 2022. My lecture notes from 2022 and 2024 can be found here.
Also, on September 16, I went to Burg Wanzeleben (near Magdeburg) to give a one-hour lecture on “Strong-field experimental relativity” as part of the IMPRS lecture week “Gravity at the Extreme: from Theory to Observation.” I tried to convince the AEI students from Hannover and Potsdam that neutron stars are awesome and that testing theories of gravity is fun!