Physics Colloquium - Black Hole Imaging: Successes, Outstanding Questions, and Future Efforts

The Event Horizon Telescope (EHT) has delivered the first horizon-scale images of supermassive black holes, opening a new window onto ultrastrong gravity and accretion physics. With the release of multi-year data, we can now probe the stability and evolution of black hole images across time. In this talk, I will review the early key successes and highlight new multi-year results. I will then focus on two surprising findings: the unexpected image symmetry and the lack of variability in the image structure, both of which pose challenges for current theoretical models of black holes. Finally, I will discuss what is required to extend black holeimaging to a broader population of sources and how future space-based interferometers can enable black hole imaging as a systematic tool for exploring fundamental physics and astrophysical engines.