Post-Newtonian cosmological modelling
TLDR
In this article, the authors developed a new approach to building cosmological models, in which small pieces of perturbed Minkowski space are joined together at reflection-symmetric boundaries in order to form a global, dynamical space-time.Abstract:
We develop a new approach to building cosmological models, in which small pieces of perturbed Minkowski space are joined together at reflection-symmetric boundaries in order to form a global, dynamical space-time. Each piece of this patchwork universe is described using post-Newtonian gravitational physics, with the large-scale expansion of the Universe being an emergent phenomenon. This approach to cosmology does not require any assumptions about nonlocal averaging processes. Our framework clarifies the relation between the weak-field limit of general relativity, and the cosmological solutions that result from solving Einstein's equations with a set of symmetry assumptions. It also allows the effects of structure formation on the large-scale expansion of the Universe to be investigated without averaging anything. As an explicit example, we use this formalism to investigate the cosmological behavior of a large number of regularly arranged pointlike masses. In this case we find that the large-scale expansion is well modelled by a Friedmann-like equation that contains terms that take the form of dust, radiation, and spatial curvature. The radiation term, while small compared to the dust term, is purely a result of the nonlinearity of Einstein's equations.read more
Citations
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Black-hole lattices as cosmological models
TL;DR: The search for solutions of Einstein's equations representing relativistic cosmological models with a discrete matter content has been remarkably fruitful in the last decade as mentioned in this paper, and in this review we disc...
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Cosmological backreaction in the presence of radiation and a cosmological constant
TL;DR: In this article, the authors construct high-precision models of the universe that contain radiation, a cosmological constant, and periodically distributed inhomogeneous matter, and find general expressions that precisely and unambiguously quantify the effect of small-scale inhomogeneity on the large-scale expansion of space.
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Parameterized post-Newtonian cosmology
TL;DR: In this article, an extension of the parameterized post-Newtonian (PPN) formalism is proposed to constrain a large class of metric theories of gravity with data collected from isolated astrophysical systems.
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The magnetic part of the Weyl tensor, and the expansion of discrete universes
TL;DR: In this paper, the authors examined the effect of the magnetic part of the Weyl tensor on the large-scale expansion of space and found that the influence of this part increases with the number of masses in the universe.
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CMB seen through random Swiss Cheese
Mikko Lavinto,Syksy Räsänen +1 more
TL;DR: In this paper, the effect of Lemaȋtre-Tolman-Bondi holes on the temperature, angular diameter distance and, for the first time in Swiss Cheese models, shear of the CMB was studied.
References
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Theory and Experiment in Gravitational Physics
TL;DR: In this article, the authors provide a complete treatment of techniques for analyzing gravitation theory and experience, taking into account the Dicke framework, basic criteria for the viability of a gravitation theories, experimental tests of the Einstein equivalence principle, Schiff's conjecture, and a model theory devised by Lightman and Lee (1973).
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On regular polytopes
Luis J. Boya,Cristian Rivera +1 more
TL;DR: In this article, the authors attributed these peculiarities and exceptions to special properties of the orthogonal groups in these dimensions: the SO(2)=\mathrm{U}(1)$ group being (abelian and) \emph{divisible, is related to the existence of arbitrarily-sided plane regular polygons, and the splitting of the Lie algebra of the O(4)-group is responsible for the Schlafli special polytopes in 4-dim., two of which percolate down to three.