A black hole’s center contains a singularity where density becomes infinite.

According to Einstein’s theory of general relativity, the core of a black hole is a singularity. This means that all the matter sucked into the black hole is crushed into a single point with zero volume but infinite density. This point is surrounded by an event horizon, the boundary beyond which nothing can escape. The singularity represents a breakdown of the known laws of physics because infinite density cannot be described by current theories.