The structure of quantum singularities on a Cauchy horizon
Abstract Spacetime singularities pose a long-standing puzzle in quantum gravity. Unlike Schwarzschild, a generic family of black holes gives rise to a Cauchy horizon on which, even in the Hartle-Hawking state, quantum observables such as ⟨T μν ⟩ — the expectation value of the stress-energy tensor —...
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| Language: | English |
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2025-07-01
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| Series: | Journal of High Energy Physics |
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| Online Access: | https://doi.org/10.1007/JHEP07(2025)218 |
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| author | Arvin Shahbazi-Moghaddam |
| author_facet | Arvin Shahbazi-Moghaddam |
| author_sort | Arvin Shahbazi-Moghaddam |
| collection | DOAJ |
| description | Abstract Spacetime singularities pose a long-standing puzzle in quantum gravity. Unlike Schwarzschild, a generic family of black holes gives rise to a Cauchy horizon on which, even in the Hartle-Hawking state, quantum observables such as ⟨T μν ⟩ — the expectation value of the stress-energy tensor — can diverge, causing a breakdown of semiclassical gravity. Because they are diagnosed within quantum field theory (QFT) on a smooth background, these singularities may provide a better-controlled version of the spacetime singularity problem, and merit further study. Here, I highlight a mildness puzzle of Cauchy horizon singularities: the ⟨T μν ⟩ singularity is significantly milder than expected from symmetry and dimensional analysis. I address the puzzle in a simple spacetime W P $$ {\mathcal{W}}_P $$ , which arises universally near all black hole Cauchy horizons: the past of a codimension-two spacelike plane in flat spacetime. Specifically, I propose an extremely broad QFT construction in which, roughly speaking, Cauchy horizon singularities originate from operator insertions in the causal complement of the spacetime. The construction reproduces well-known outer horizon singularities (e.g., in the Boulware state), and remarkably, when applied to W P $$ {\mathcal{W}}_P $$ , gives rise to a universal mild singularity structure for robust singularities, ones whose leading singular behavior is state-independent. I make non-trivial predictions for all black hole Cauchy horizon singularities using this, and discuss extending the results beyond robust singularities and the strict near Cauchy horizon limit. |
| format | Article |
| id | doaj-art-3d985e541b2648cd9d2f86eaac6e835a |
| institution | Kabale University |
| issn | 1029-8479 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Journal of High Energy Physics |
| spelling | doaj-art-3d985e541b2648cd9d2f86eaac6e835a2025-08-20T04:01:47ZengSpringerOpenJournal of High Energy Physics1029-84792025-07-012025713910.1007/JHEP07(2025)218The structure of quantum singularities on a Cauchy horizonArvin Shahbazi-Moghaddam0Center for Theoretical Physics and Department of Physics, University of CaliforniaAbstract Spacetime singularities pose a long-standing puzzle in quantum gravity. Unlike Schwarzschild, a generic family of black holes gives rise to a Cauchy horizon on which, even in the Hartle-Hawking state, quantum observables such as ⟨T μν ⟩ — the expectation value of the stress-energy tensor — can diverge, causing a breakdown of semiclassical gravity. Because they are diagnosed within quantum field theory (QFT) on a smooth background, these singularities may provide a better-controlled version of the spacetime singularity problem, and merit further study. Here, I highlight a mildness puzzle of Cauchy horizon singularities: the ⟨T μν ⟩ singularity is significantly milder than expected from symmetry and dimensional analysis. I address the puzzle in a simple spacetime W P $$ {\mathcal{W}}_P $$ , which arises universally near all black hole Cauchy horizons: the past of a codimension-two spacelike plane in flat spacetime. Specifically, I propose an extremely broad QFT construction in which, roughly speaking, Cauchy horizon singularities originate from operator insertions in the causal complement of the spacetime. The construction reproduces well-known outer horizon singularities (e.g., in the Boulware state), and remarkably, when applied to W P $$ {\mathcal{W}}_P $$ , gives rise to a universal mild singularity structure for robust singularities, ones whose leading singular behavior is state-independent. I make non-trivial predictions for all black hole Cauchy horizon singularities using this, and discuss extending the results beyond robust singularities and the strict near Cauchy horizon limit.https://doi.org/10.1007/JHEP07(2025)218Black HolesSpacetime Singularities |
| spellingShingle | Arvin Shahbazi-Moghaddam The structure of quantum singularities on a Cauchy horizon Journal of High Energy Physics Black Holes Spacetime Singularities |
| title | The structure of quantum singularities on a Cauchy horizon |
| title_full | The structure of quantum singularities on a Cauchy horizon |
| title_fullStr | The structure of quantum singularities on a Cauchy horizon |
| title_full_unstemmed | The structure of quantum singularities on a Cauchy horizon |
| title_short | The structure of quantum singularities on a Cauchy horizon |
| title_sort | structure of quantum singularities on a cauchy horizon |
| topic | Black Holes Spacetime Singularities |
| url | https://doi.org/10.1007/JHEP07(2025)218 |
| work_keys_str_mv | AT arvinshahbazimoghaddam thestructureofquantumsingularitiesonacauchyhorizon AT arvinshahbazimoghaddam structureofquantumsingularitiesonacauchyhorizon |