On cosmological expansion and local physics

Abstract

We find an exact convergence in the local dynamics described by two supposedly antagonistic approaches in modern cosmology: one starting from an expanding universe perspective such as FLRW, the other based on a local model ignoring any notion of expansion, such as Schwarzschild dS. Both models are in complete agreement when the local effects of the expansion are circumscribed to the presence of the cosmological constant. We elaborate in the relevant role of static backgrounds like the Schwarzschild-dS metric in standard form as the most proper coordinatizations to describe physics at the local scale. Finally, making use of an old and too often forgotten relativistic kinematical invariant, we clarify some widespread misunderstandings on space expansion, cosmological and gravitational redshifts. As a byproduct we propose a {\sl unique and unambiguous} prescription to match the local and cosmological expression of a specific observable.

14 pages + appendices

References in corpus (6)

• Cosmological expansion and local physics
• Geodesic equation in Schwarzschild--(anti-)de Sitter space--times: Analytical solutions and applications
• Solar system effects in Schwarzschild--de Sitter spacetime
• Revisiting observables in generally covariant theories in the light of gauge fixing methods
• Evolution of gravitational orbits in the expanding universe
• A diatribe on expanding space