New research from Penn State scientists reveals that dynamic black holes may adhere to Hawking-style thermodynamics using an alternative entropy measure. This study, led by Abhay Ashtekar, was published in the journal Physical Review Letters on July 2, 2026.
Understanding Black Holes and Thermodynamics
Black holes are among the universe's most extreme entities, compacting massive amounts of mass into a small region, creating gravity so strong that not even light can escape. Historically, physicists have employed complex equations from Einstein's theory of general relativity and quantum mechanics to describe their properties. In the 1970s, Stephen Hawking and others established parallels between the laws of thermodynamics and black hole mechanics, leading to a new understanding of their properties.
“Hawking's laws of black hole mechanics provided a satisfying connection between extreme and ordinary physics and have been the paradigm for 50 years, but they have a serious limitation,” Ashtekar noted. The original laws were formulated for black holes at equilibrium, but these cosmic phenomena are constantly changing, forming, merging, and evaporating.
New Entropy Measure for Dynamic Black Holes
The research team proposes a new measure for a black hole's entropy, which is a measure of disorder that cannot decrease according to the second law of thermodynamics. This alternative approach links entropy more closely to the physical properties of a black hole, such as its spin and energy. It could enhance our understanding of the dynamic processes that black holes undergo, including evaporation and merging with others.
“These analogies only really work for a black hole that is at equilibrium,” said Jonathan Shu, a graduate student and co-author. The team suggests replacing event horizons with “dynamical horizons,” which focus on the properties of a black hole at a specific moment, thus avoiding the teleological issues that arise with event horizons.
Implications of the New Research
This groundbreaking research has the potential to extend the first and second laws of thermodynamics to non-equilibrium black holes, overcoming limitations of previous paradigms. “We can apply these generalized laws to better understand evaporating black holes in quantum theory and black hole mergers,” Ashtekar stated, noting the relevance to recent detections made by the LIGO-Virgo-KAGRA collaboration using gravitational waves.
- Publication Date: July 2, 2026
- Journal: Physical Review Letters
- Key Researchers: Abhay Ashtekar, Daniel E. Paraizo, Jonathan Shu
- Key Concepts: Thermodynamics, Black Holes, Quantum Gravity
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