Weyl Curvature Hypothesis in Light of Quantum Backreaction at Cosmological Singularities or Bounces

@article{Hu2021WeylCH,
  title={Weyl Curvature Hypothesis in Light of Quantum Backreaction at Cosmological Singularities or Bounces},
  author={Bei-Lok Hu},
  journal={Universe},
  year={2021}
}
  • B. Hu
  • Published 3 October 2021
  • Physics
  • Universe
The Weyl curvature constitutes the radiative sector of the Riemann curvature tensor and gives a measure of the anisotropy and inhomogeneities of spacetime. Penrose’s 1979 Weyl curvature hypothesis (WCH) assumes that the universe began at a very low gravitational entropy state, corresponding to zero Weyl curvature, namely, the Friedmann–Lemaître–Robertson–Walker (FLRW) universe. This is a simple assumption with far-reaching implications. In classical general relativity, Belinsky, Khalatnikov and… 

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TLDR
The extension of the ideas of quantum cosmology and, in particular, the proposal of Hartle and Hawking for the boundary conditions of the Universe, to models which incorporate fermions in a realistic manner is considered, finding this to imply that the fermion modes start out in their ground state.
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