The Steep Price of No Hair in a Modified Loop Quantum Cosmology
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arXiv
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| Format: | Preprint |
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2026
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| _version_ | 1866911533944012800 |
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| author | Motaharfar, Meysam Singh, Parampreet |
| author_facet | Motaharfar, Meysam Singh, Parampreet |
| contents | A specific loop quantum cosmology model, mLQC-I, motivated by Thiemann's regularization of the Hamiltonian constraint, leads to the resolution of the big bang singularity and bounce in the isotropic setting, in which either the pre-bounce or post-bounce epoch is necessarily characterized by an emergent Planckian de Sitter phase. In this work we explore the Planckian physics of this mLQC-I prescription for the Bianchi-I spacetimes. We show that as in the isotropic model, there exists an emergent de Sitter phase which naturally dampens anisotropic shear and removes cosmic hair. However, this isotropization comes at a steep price: although a macroscopic post-bounce regime is achieved, the universe never becomes truly classical. We further demonstrate that this isotropization mechanism is non-generic. These results help clarify and reinterpret recent results by Gan et al. [1] that, in anisotropic mLQC-I, quantum gravity effects generically damp anisotropic shear in a way that is independent of initial conditions and the matter content, and that this anisotropic shear damping mechanism arises from a novel quantum gravity effect. Our work explains the origin of this mechanism and its limitations in the mLQC-I model. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2603_18175 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | The Steep Price of No Hair in a Modified Loop Quantum Cosmology Motaharfar, Meysam Singh, Parampreet General Relativity and Quantum Cosmology A specific loop quantum cosmology model, mLQC-I, motivated by Thiemann's regularization of the Hamiltonian constraint, leads to the resolution of the big bang singularity and bounce in the isotropic setting, in which either the pre-bounce or post-bounce epoch is necessarily characterized by an emergent Planckian de Sitter phase. In this work we explore the Planckian physics of this mLQC-I prescription for the Bianchi-I spacetimes. We show that as in the isotropic model, there exists an emergent de Sitter phase which naturally dampens anisotropic shear and removes cosmic hair. However, this isotropization comes at a steep price: although a macroscopic post-bounce regime is achieved, the universe never becomes truly classical. We further demonstrate that this isotropization mechanism is non-generic. These results help clarify and reinterpret recent results by Gan et al. [1] that, in anisotropic mLQC-I, quantum gravity effects generically damp anisotropic shear in a way that is independent of initial conditions and the matter content, and that this anisotropic shear damping mechanism arises from a novel quantum gravity effect. Our work explains the origin of this mechanism and its limitations in the mLQC-I model. |
| title | The Steep Price of No Hair in a Modified Loop Quantum Cosmology |
| topic | General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2603.18175 |