Black hole singularity is a surface not a point

Researchers argue that black hole singularities are two-dimensional surfaces rather than points, as observers falling along different trajectories lose causal contact before reaching the center due to the spatial-causal distance paradox in general relativity. For rotating black holes, the singular surface likely exists at the inner horizon where quantum perturbations trigger mass inflation and collapse. The findings suggest that quantum states of black holes may reside at these effectively 2-dimensional singular surfaces in thermodynamic equilibrium with Hawking radiation.