Astronomers have developed a set of equations that accurately describe the reflection of space in diffracted light around a black hole. The distance between each reflection depends on the viewing angle relative to the black hole and its rotation speed. Albert Sneppen, a physics student at the Niels Bohr Institute in Denmark, came up with this solution in July 2021. Mr. Sneppen said: He also offers new opportunities to test our understanding of gravity and black holes. ”

Black holes are known for their extremely large gravity, as light cannot escape their gravitational field. Just outside a black hole’s event horizon, the gravitational field is so strong that the curvature of spacetime is nearly circular, and photons entering that space follow that curvature. This causes the light path to appear twisted and curved from our perspective. At the innermost edge of this space, just outside the event horizon, we see the so-called photon ring. In this ring, photons orbit around the black hole several times before falling or flying into space. This means that light from distant objects behind a black hole can be magnified several times, distorted, and reflected.

Scientists knew about this effect before Sneppen’s work, but it was difficult to explain it mathematically. Sneppen reformulated the path of light and quantified its linear stability using a second-order differential equation. He not only explained mathematically why images repeat at intervals e2π, ​​but also showed that this applies to rotating black holes, and that the distance between repeats depends on the rotation. “We found that if the rotational speed is very fast, we no longer need to get 500 times closer to the black hole, much less,” Sneppen said.In theory, a black hole could be surrounded by an infinite number of lights. There should be a ring. The shadow of a supermassive black hole has already been photographed once, so we will get better images as time goes on, and there are already plans to photograph the photon ring. One day, images of infinity near black holes could become a tool for studying not only the space-time physics of black holes, but also the infinitely repeating objects behind them.