UNIVERSITY PARK, Pa. — Penn State researchers have extended Stephen Hawking’s foundational black hole mechanics to dynamic systems that evolve over time.

Key Finding

The team proposes a new entropy measure for black holes, replacing event horizons with “dynamical horizons” that characterize black holes at specific moments rather than relying on future predictions.

The Problem Being Solved

As Jonathan Shu explains, “event horizons can form and grow in flat regions of space-time” where “their properties cannot be determined just by the local physics.” This teleological issue prevented Hawking’s laws from applying to black holes that form, merge, and evaporate.

The Solution

The research demonstrates that dynamical horizons—already used in black hole simulations—overcome this limitation by depending only on current physical properties rather than future events.

Significance

Abhay Ashtekar notes this work allows physicists to “extend the first and second laws of thermodynamics to black holes that are not at equilibrium,” enabling better understanding of evaporating black holes and mergers detected by gravitational wave observatories like LIGO.

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Journal: Physical Review Letters
DOI: 10.1103/3c1r-v8f1
Article Title: Thermodynamics of Black Holes, Far from Equilibrium
Publication Date: June 24, 2026

Source: EurekAlert