Asked by Ben
A black hole is an area that has so much mass concentrated in it there is no way for a nearby object to escape its gravitational pull. Therefore, there is no way of knowing for certain what lies at the heart of a black hole. Einstein’s theory of general relativity, however, suggests that at the centre lies a gravitational singularity. Here, matter is crushed to infinite density under the pull of infinite gravity. At a singularity, space and time cease to exist.
Elisa Jones, Science Museum explainer