The unification of general relativity and quantum field theory, often referred to as a theory of quantum gravity, is a major goal in theoretical physics. While such a theory does not currently exist, it is anticipated that it would provide a more comprehensive framework for understanding the behavior of extreme objects like black holes.
Black holes are described by general relativity, which predicts the existence of a singularity at the center of a black hole—a point of infinite density and curvature. However, the singularity is hidden behind the event horizon, making it inaccessible to direct observation.
In the realm of quantum gravity, it is speculated that the theory may modify the description of singularities. Quantum effects could potentially resolve the singularity, replacing it with a different structure or providing insights into its true nature. However, until a theory of quantum gravity is established, it is difficult to make definitive statements about the actual radius or nature of black hole singularities.
Current approaches to quantum gravity, such as string theory or loop quantum gravity, are active areas of research. These theories aim to unify gravity with quantum mechanics and may shed light on the behavior of black holes at the quantum level. Nonetheless, the precise details of the singularity and its resolution remain uncertain until a successful theory of quantum gravity is developed and confirmed by empirical evidence.