https://apnews.com/75303baeb5af4643938128b403298a36 > WASHINGTON (AP) — Black holes are cosmic prisons, where nothing escapes, not light or even data. But lots did come out of Wednesday's first image of the shadowy edge of a supermassive black hole. Here are four things we learned: > Scientists have known for decades that black holes exist, but only indirectly. Three years ago, they essentially heard the sound of two smaller black holes crashing together to form a gravitational wave. The image revealed Wednesday showed the edges of the black hole — called the "event horizon" — for the first time.