Black hole. Computer artwork of a black hole distorting spacetime on a starfield background. A black hole is a super-dense remnant left after the death of a massive star. The gravitational field around it is so strong that not even light can escape. Gravitational fields can be represented by depressions in flat spacetime. Here, normal spacetime is shown as the flat disc, which spirals down in a steeper and steeper slope, representing greater gravitational fields, to the black hole. The idea that spacetime can be distorted by mass comes from Einstein's theories of relativity.