A mathematical fingerprint can now tell the difference between a real black hole and a smooth, empty shell that looks just like it.
April 29, 2026
Original Paper
Chaos of Berry curvature for BPS microstates
arXiv · 2604.23287
The Takeaway
Berry curvature is a geometric property that can distinguish between black hole microstates and smooth, horizonless states. Microstates resemble random matrices and exhibit chaotic behavior, while the smooth versions do not. This provides a concrete diagnostic for one of the biggest debates in quantum gravity. It helps physicists understand if black holes are truly empty voids or if they are made of complex, microscopic structures. This discovery brings us closer to a Theory of Everything that can link the physics of the very small with the physics of the very large.
From the abstract
We expect black hole microstates to differ in their chaotic properties from states associated with other geometries. For supersymmetric black holes, ordinary level statistics cannot diagnose this distinction, since their energy levels are exactly degenerate. We propose that there is an intrinsic probe of chaos, encoded in the mixing of the microstates under changes in the couplings of the theory, as determined by the non-Abelian Berry curvature of the BPS states under certain deformations. For s