Physicists investigate theoretical possibility of black hole splitting

A theoretical study published in Physical Review D examines whether a single black hole could split into two smaller objects, a process that contradicts standard observations of black hole mergers.

Researchers Giacomo Cacciapaglia, Francesco Sannino, Manuel Del Piano, and Vania Vellucci found that the second law of thermodynamics and the area theorem typically prevent such a split. Because black hole entropy is proportional to the area of its event horizon, dividing one large black hole into two smaller ones would generally reduce total entropy, making the process unfavorable.

The team identified a narrow theoretical loophole: extremely fast-spinning Kerr black holes rotating near their maximum possible rate might satisfy the necessary entropy conditions. However, the study notes that meeting thermodynamic requirements does not guarantee a physical mechanism exists to facilitate the split, nor does it ensure the resulting fragments would avoid immediately merging again. The researchers described the potential geometric transition of the event horizon using the term ‘pair-of-pants topologies’ to illustrate the division.