Black holes reflect the universe, and the equation explains how

A group of astronomers has developed a mathematical equation that may finally describe how black holes mirror our universe. Until now, to observe this, researchers have looked 500 times closer to the edge of these objects or used the exponential function of two pi, that it^2π. However, it was difficult to describe mathematically why this happened.

The mathematical solution to explain the phenomenon was developed by Albert Snippen, a physics student at the Niels Bohr Institute in Denmark, in July 2021, in a paper published in the journal Scientific reports. This discovery gave scientists a potential new tool for observing the gravitational environment around black holes.

There is something fantastically beautiful in understanding why images repeat themselves so elegantly. Moreover, it provides new opportunities to test our understanding of gravity and black holes.

Lukács Pawel Szczepanski

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The gravitational force of a black hole

Black holes are known for their intense gravitational pull, from which even light cannot escape up to a certain radius known as the event horizon. However, beyond this limit, its gravitational field is still incredibly strong, to the point of bending the spacetime surrounding it circularly.

Any photon that enters this space will have to follow this curvature before falling into the black hole or being able to escape into space. Thus, at the boundary of the event horizon it is possible to see a ring of photons responsible for distorting the path of light, when viewed from our perspective.

This phenomenon, known as gravitational lensing, allows light from distant objects at the bottom of the black hole to be magnified, distorted and “reflected” many times over. This way, the closer you are to the event horizon, the more reflections from distant objects you can see.

To explain why this happened, Snepen reformulated the path of light and determined its linear stability, using second-order differential equations. This formula allowed us to determine not only how the universe reflects, but is also useful for when these objects rotate.

It turns out that when it rotates very quickly, you no longer need to get closer to the black hole by a factor of 500, but much less. In fact, each image is now only 50, five, or even two times closer to the edge of the black hole.

Albert Sneben

In practice, it will be difficult to notice this soon, but in theory there should be countless rings of light around these supermassive objects. Perhaps in the future it will be possible to observe these photons around these objects with better images, which will allow us to study not only the space-time physics of the black hole, but also the objects behind it.