Matthew Dodelson, a physicist at Harvard University, presents this talk at the Institute for Advanced Study's Wolfensohn Hall as part of the seminar series Black Holes from Theory to Observations. He takes up quasinormal ringdown, the characteristic damped oscillations a perturbed black hole emits as it settles back to equilibrium, and asks what the same mathematics looks like when applied to quantum systems rather than classical spacetimes. The talk works through how quasinormal modes are defined and computed, what they reveal about the underlying dynamics, and where the classical black hole picture and quantum descriptions agree or diverge. Dodelson keeps the discussion technical, aimed at researchers following current work on gravitational wave ringdown signals and their theoretical underpinnings, with the quantum analogy used to probe questions that are harder to access directly in gravity. It is a specialist seminar talk rather than an introductory lecture, assuming familiarity with black hole perturbation theory and quantum field theory.