Brisk Light: A New Middle-Ground Model for Black-Hole Imaging
Physicists propose 'brisk light', an intermediate approach between fast-light (single emission time per image) and slow-light (full time-delay map) to model how photons from different moments reach us around black holes. Brisk light preserves the dominant time-delay structure while reducing computational costs, and while current Event Horizon Telescope images of M87* and Sgr A* are well captured with fast-light, the next generation of observatories aiming to resolve photon rings will need timing-accurate models.