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arXiv · 2603.12319

Quantum Signatures of Cosmic Topology: How Casimir Backreaction Transmits Isotropy Violation

Anna Negro·Kurt Hinterbichler·Glenn D. Starkman·Yashar Akrami·Stefano Anselmi·Javier Carrón Duque·Mikel Martin Barandiaran·Thiago S. Pereira·George Alestas·Craig J. Copi·Fernando Cornet-Gomez·Linn Htat Lu·Andrew H. Jaffe·Arthur Kosowsky·Deyan P. Mihaylov·Joline Noltmann·José Javier Ortega Gómez·Catherine Petretti·Amirhossein Samandar·Andrius Tamosiunas
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Abstract

A finite, scheme-independent Casimir contribution to the stress-energy tensor arises naturally for quantum fields in universes with non-trivial spatial topology. We compute this Casimir stress-energy tensor contribution for a conformally coupled scalar field and for a minimally coupled scalar field. We show that, for the conformally coupled case, the backreaction of this contribution to the Einstein equations during an expanding de Sitter phase drives anisotropic expansion even when the Universe begins in a locally homogeneous and isotropic state. We conclude that quantum imprints of the underlying non-trivial topology inevitably give rise to local departures from homogeneity and isotropy.

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Anna Negro, Kurt Hinterbichler, Glenn D. Starkman, Yashar Akrami, Stefano Anselmi, Javier Carrón Duque, Mikel Martin Barandiaran, Thiago S. Pereira, George Alestas, Craig J. Copi, Fernando Cornet-Gomez, Linn Htat Lu, Andrew H. Jaffe, Arthur Kosowsky, Deyan P. Mihaylov, Joline Noltmann, José Javier Ortega Gómez, Catherine Petretti, Amirhossein Samandar, Andrius Tamosiunas. 2026-09-08. Quantum Signatures of Cosmic Topology: How Casimir Backreaction Transmits Isotropy Violation. https://arxiv.org/abs/2603.12319

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