Re-evaluation of dlk of the normalised Friedmann-Lemaitre-Robertson-Walker model: Implications for Hubble constant determinations

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ÖZTAŞ A. M., Smith M. L.

NEW ASTRONOMY, vol.88, 2021 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 88
  • Publication Date: 2021
  • Doi Number: 10.1016/j.newast.2021.101609
  • Journal Name: NEW ASTRONOMY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Communication Abstracts, INSPEC, Metadex, Civil Engineering Abstracts
  • Hacettepe University Affiliated: Yes


The description of spacetime is an fundamental problem of cosmology. We explain why the current assignments of spacetime geometries for dlk of the Friedmann-Lemaitre-Robertson-Walker (FLRW) model are probably incorrect and suggest more useful descriptions. We show that dlk represents not only curvature but the influence of matter density on the extent of spacetime between massive objects. Recent analyses of supernovae type Ia (SNe Ia) and HII/GEHR data with the FLRW model present the best fits with a small value for dlm and a large dlk. These results are consistent with our Universe exhibiting sparse matter density and quasi-Euclidean geometry and the small dlm value agrees with Big Bang nucleosynthesis calculations. We suggest the geometry of our current Universe is better described by a value for dlk approximate to 1 rather than 0. As an example we extend the FLRW model towards the Big Bang and discover a simple explanation of how matter creation developed into the currently geometrically flat Universe with sparse, homogeneous, isotropic matter and energy distributions. Assigning dlk approximate to 1 to describe quasi-Euclidean spacetime geometry is also useful for estimating H0 and should help resolve the "tension" surrounding current estimates by different investigators.