Gravitational surface tension as the origin for the black hole entropy

In this work, we explore the thermodynamics of black holes using the Gouy–Stodola theorem, traditionally applied to mechanical systems relating entropy production to the difference between reversible and irreversible work. We model black holes as gravitational bubbles with surface tension defined at the event horizon, deriving the Bekenstein–Hawking entropy relation for nonrotating black holes. One extends this approach to rotating black holes, incorporating the effects of angular momentum, demonstrating that the Gouy–Stodola theorem can similarly derive the entropy–area law in this case. Additionally, we analyze the merging of two black holes, showing that the resultant total entropy exceeds the sum of the individual entropies, thereby adhering to the second law of thermodynamics. Our results suggest that gravitational surface tension is a key factor in black hole thermodynamics, providing a novel and coherent framework for understanding the entropy production in these extreme astrophysical objects.