Einstein believed that black holes didn't really exist. But they do: that much we know. We don't know much else about them.

and a stellar ring — despite possessing one of the most violent supermassive black holes ever seen in a spiral galaxy.

supermassive black hole could explain the Cosmic Horseshoe's unusual appearance. In astronomical observations, the system forms a halo of light known as an Einstein ring. As the famed physicist ...