A gravitational singularity, spacetime singularity or simply singularity is a location in spacetime where the mass and gravitational field of a celestial body is predicted to become infinite by general relativity in a way that does not depend on the coordinate system.
Source : Wikipedia
Calculations based on Einstein's theory of General Relativity show that any object which is sufficiently massive as to have a gravitational field strong enough to distort spacetime to the extent that light itself could not escape, would collapse to form a Black Hole - the central point of which would necescarily have infinite density, and therefore infinite mass. The same calculations show that this point is also infinitely small. Leading to an unresolved logical paradox which questions how an infinitely small entity can have infinite mass.
Other theories (e.g. loop quantum gravity) suggest that such singularities are impossible - due to the (proposed) quantum nature of spacetime, which means that no object can be smaller than a certain size.
Also see : The Gravitational constantplugin-autotooltip__plain plugin-autotooltip_bigThe Gravitational constant
The gravitational attraction between two objects is dependent on the mass of the objects, the distance between them, and the gravitational constant (G).
The masses and distance can vary, but the constant, as the name implies, is always a fixed number. and Naked singularitiesplugin-autotooltip__plain plugin-autotooltip_bigNaked singularities
"In general relativity, a naked singularity is a hypothetical gravitational singularity without an event horizon. In a black hole, the singularity is completely enclosed by a boundary known as the event horizon, inside which the gravitational force of the singularity is so strong that light cannot escape. Hence, objects inside the event horizon—including the singularity itself—cannot be directly observed. A naked singularity, by contrast, would be observable from the outsid…