Explain then how it has so much gravity. It's got no mass, so no weight, but it's dense, so it's still made up of something otherwise there would be nothing to make it dense. Unless, it's simply a place in space where the gravity is really strong. Einstein described gravity as big bends in space, like a bend in another dimension that causes things to move towards each other. But according to other theories, gravity is given by a particle. It's one of the 4 types of energy: nuclear, strong gravity, weak gravity and electromagnetism. So according to that, if a singularity is to have lots of gravity, it must still be made up of something. Even if it's just made up of energy, that has no mass.