Physicists at Pennsylvania State University have published research that advances our understanding of black hole mechanics. For decades, the laws of thermodynamics were limited to stable black holes in equilibrium. This new work replaces traditional event horizons with dynamical horizon segments to describe objects that form, merge, and evaporate in real-time.
The team, led by Abhay Ashtekar, found that Einstein’s equations allow these dynamical horizons to follow rules similar to the first and second laws of thermodynamics. By calculating how energy and angular momentum change at specific moments, they have created a way to define entropy for black holes that are far from a stable state. This shift addresses a long-standing gap in gravitational physics where previous models required knowledge of the black hole's entire future to define its current entropy.
This research suggests that quantum effects play a significant role in the behavior of these objects. Daniel Paraizo, a team member, noted that including quantum effects may lead to the total disappearance of event horizons, aligning with theories supported by Stephen Hawking before his death. The team continues to apply these findings to theories of gravity beyond general relativity and is using loop quantum gravity to study the final stages of black hole evaporation.
These findings provide a path forward for researchers to explain puzzling data from numerical simulations of black hole mergers. The study is published in Physical Review Letters and offers a new framework for analyzing the evolution of black holes across time.