The study, headed by Enrico Rinaldi, is based upon an idea known as holographic duality. This states that the theory of gravity and the theory of particles are mathematically the same. However, the theory of gravity describes the third dimension, while particle theory describes the second. As far as black holes go, both of these theories are relevant in describing how they operate. The University of Michigan study looked into what this holographic duality idea means for black holes and what’s inside of them.
Source: What Is Inside A Black Hole? Here’s What Astronomers Say