2013/09/30 by Giovanni Acquaviva, Luca Bonetti, Guido Cognola +1
Mathematics · Physics and Astronomy · #Applied mathematics #Astron #Astronomy #Astrophysics #Black Holes and Theoretical Physics #Classical mechanics #Cosmology #Cosmology and Gravitation Theories #Dark energy #Direction cosine #Friedmann–Lemaître–Robertson–Walker metric #Galaxies: Formation, Evolution, Phenomena #Geodesic #Geometry #Horizon #Hubble volume #Hubble's law #Mathematical analysis #Mathematical physics #Mathematics #Observability #Observer (physics) #Physics #Quantum mechanics #Theoretical physics #astro-ph.CO #gr-qc
paper · pdf · doi:10.1103/physrevd.88.124024
14 pages, no figures, added references and a new paragraph in Sec.4. Final version accepted in PRD
arxiv created 2013/11/30 · openalex publication_date 2013/12/09 · arxiv updated 2015/06/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
In this work we take moves from the debate triggered by Melia et al. in [J. Cosmol. Astropart. Phys. 09 (2012) 029; Mon. Not. R. Astron. Soc. 421, 3356 (2012)] and followed by opposite comments by Lewis and Oirschot in [Mon. Not. R. Astron. Soc. Lett. 423, 26 (2012); 431, 25 (2013)]. The point in question regards the role of the Hubble horizon as a limit for observability in a cosmological setting. We propose to tackle the issue in a broader way by relating it to the causal character of the Hubble surface and to the tracing of null trajectories, focusing on both three-fluids and generalized Chaplygin gas models. The results should make clear that for quite reasonable and physically motivated models, light rays reaching a comoving observer at R(t0)=0 have never traveled a distance greater than the proper radius of the horizon until t0.