Imagine a galaxy reflected in a funhouse hall of mirrors. The galaxy could be seen repeating again and again, with each image becoming more distorted and grotesque. Near the event horizon of a black hole, one of the most warped places in the cosmos, that’s how the universe looks. What such regions looked like physicists had some previous ideas about. What could be seen around black holes a new calculation has shown exactly, opening up new methods to test Einstein’s theory of general relativity.
When the heavy object is looked at directly wouldn’t give eyes much to focus on; by the black hole’s event horizon, light rays get swallowed, the point at which nothing can ever escape its massive gravitational influence. But if one has placed a galaxy behind the black hole and then looks off to the side, a distorted image of the galaxy can be seen.
The black hole’s extreme gravity makes such light would get bent toward the line of sight. The galaxy would seem to be far away from the black hole, not directly behind it. The gravity around the black hole is space-time and so intense and is so incredibly warped light itself can orbit the black holes at a certain distance. Some of the lights from the background galaxy even get trapped.
In order to get trapped in orbit, the light would need to come to the exact right distance from the black hole. A black hole can be hit by light at an angle that allows it to make one loop before eventually escaping. When one looks at the edge of the black hole, eyes would see one image of the background galaxy from its deflected light. Then 2nd image of the galaxy could be seen from light rays that managed to make a single orbit before escaping and then again from light rays that made two orbits, and then three, and so on. Physicists for decades have known through simple estimates that each image is e^2𝜋 times closer than the last.