High Energy Theory Seminar: Mihailo Čubrović

Title: Bubbling geometries, chaos and ensemble averaging

Abstract: We consider the dynamics of geodesics and waves in bubbling geometries (Lin-Lunin-Maldacena solutions and bubbling supertubes) as a diagnostic tool for chaos and ensemble averaging phenomena, and compare the outcome to the known results for black hole backgrounds. We show that both geodesics and waves are sensitive to the amount of supersymmetry (1/2 BPS vs 1/4 BPS vs 1/16 BPS), the interior region of the geometry (the existence and length of a BTZ-like throat or AdS3 throat) and the existence of the horizon. While the wave probes expectedly show stronger chaos in less supersymmetric and more black-hole-like backgrounds, the geodesics paradoxically behave in the opposite way - showing the strongest chaos in the most supersymmetric and the smoothest geometries. We explain this in terms of the singular nature of the eikonal limit. We also comment on the self-averaging properties of the probes and in this light discuss the consistence of the ensemble averaging paradigm for black holes.