2011/11/30 by Timothy Clifton, Chris Clarkson, Philip Bull · 1 citation
Physics and Astronomy · #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #astro-ph.CO #gr-qc
paper · pdf · doi:10.1103/physrevlett.109.051303
published as Phys. Rev. Lett. 109, 051303 (2012) · 5 pages, 1 figure
openalex publication_date 2012/08/01 · arxiv created 2012/08/03 · arxiv updated 2015/06/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The question of whether the Universe is spatially homogeneous and isotropic on the largest scales is of fundamental importance to cosmology, but has not yet been answered decisively. Surprisingly, neither an isotropic primary CMB nor combined observations of luminosity distances and galaxy number counts are sufficient to establish such a result. The inclusion of the Sunyaev-Zel'dovich effect in CMB observations, however, dramatically improves this situation. We show that even a solitary observer who sees an isotropic blackbody CMB can conclude that the universe is homogeneous and isotropic in their causal past when the Sunyaev-Zel'dovich effect is present. Critically, however, the CMB must either be viewed for an extended period of time, or CMB photons that have scattered more than once must be detected. This result provides a theoretical underpinning for testing the Cosmological Principle with observations of the CMB alone.