Artist impression of a blackhole Shutterstock/ Vadim Sadovski
Black holes could have a unique version of pressure that is not found anywhere else in the universe. Quantum mechanics' effect on gravity at the edges of black holes has been calculated to show that these regions could have pressure. This was a surprising finding for physicists.
It is a big mystery how quantum mechanics and gravity can be combined. The edge of a dark hole is one region that has some answers.