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arXiv · 2605.20013

Approaching the surface of an Exotic Compact Object

Shokoufe Faraji·Samir D. Mathur
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Abstract

Many approaches to quantum gravity require replacing the traditional black hole geometry with an Exotic Compact Object (ECO), which has a large but not infinite redshift at its surface. We argue that near the ECO surface, the vacuum Einstein equations imply a metric that is chaotic, with increasingly large oscillations as we approach the surface. This behavior is analogous to the `cosmic billiards' found in the BKL analysis of cosmology near the big bang. For the ECO, some of the potential walls of this billiards change sign to become `cliffs', resulting in a runaway behavior where some compact directions squeeze to zero size. In string theory such squeezing yields a natural continuation to the interior geometry of fuzzballs, where compact directions collapse to create monopoles.

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Shokoufe Faraji, Samir D. Mathur. 2026-05-19. Approaching the surface of an Exotic Compact Object. https://arxiv.org/abs/2605.20013

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