The generally covariant meaning of space distances

Capozziello, Salvatore; Chiappini, A.; Fatibene, L.; Orizzonte, A.

doi:10.1140/epjp/s13360-020-00968-7

Cited by 2 publications

(1 citation statement)

References 19 publications

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“…One can show that defining atomic clocks then a space-time decomposition follows [see 30,31], and one can define space and time lengths out of each specific atomic clock. That is very well known in standard GR, though it extends to a Weyl geometry [32], as required in Palatini f (R)-theories.…”

Section: Introductionmentioning

confidence: 99%

Solar System Tests in Brans-Dicke and Palatini f(R)-theories

Bonino,

Camera,

Fatibene

et al. 2020

Preprint

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We compare Mercury's precession test in standard General Relativity (GR), Brans-Dicke theories (BD), and Palatini f (R)-theories. We avoid post Newtonian (PN) approximation and compute exact precession in these theories. We show that the well-known mathematical equivalence between Palatini f (R)-theories and a specific subset of BD theories does not extend to a really physical equivalence among theories since equivalent models still allow different incompatible precession for Mercury depending on the solution one chooses. As a result one cannot use BD equivalence to rule out Palatini f (R)-theories. On the contrary, we directly discuss that Palatini f (R)-theories can (and specific models do) easily pass Solar System tests as Mercury's precession.

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Section: Introductionmentioning

confidence: 99%

Solar System Tests in Brans-Dicke and Palatini f(R)-theories

Bonino,

Camera,

Fatibene

et al. 2020

Preprint

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The effective equation of state in Palatini $$f({{\mathcal {R}}})$$ cosmology

et al. 2023

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We investigate how the cosmological equation of state can be used for scrutinizing extended theories of gravity, in particular, the Palatini $$f({{\mathcal {R}}})$$ f ( R ) gravity. Specifically, the approach consists, at first, in investigating the effective equation of state produced by a given model. Then, the inverse problem can also be considered in view of determining which models are compatible with a given effective equation of state. We consider and solve some cases and show that, for example, power-law models are (the only models) capable of transforming barotropic Equations of State into effective barotropic ones. Moreover, the form of equation of state is preserved (only) for $$f({{\mathcal {R}}})={{\mathcal {R}}}$$ f ( R ) = R , as expected. In this perspective, modified Equations of State are a feature capable of distinguishing extended gravity with respect to general relativity. We investigate also quadratic and non-homogeneous effective Equations of State showing, in particular, that they contain the Starobinsky model and other ones.

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The generally covariant meaning of space distances

Cited by 2 publications

References 19 publications

Solar System Tests in Brans-Dicke and Palatini f(R)-theories

Solar System Tests in Brans-Dicke and Palatini f(R)-theories

The effective equation of state in Palatini $$f({{\mathcal {R}}})$$ cosmology

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