Spatial curvature falsifies eternal inflation

Matthew Kleban, Marjorie Schillo

    Research output: Contribution to journalArticlepeer-review


    Inflation creates large-scale cosmological density perturbations that are characterized by an isotropic, homogeneous, and Gaussian random distribution about a locally flat background. Even in a flat universe, the spatial curvature measured within one Hubble volume receives contributions from long wavelength perturbations, and will not in general be zero. These same perturbations determine the Cosmic Microwave Background (CMB) temperature fluctuations, which are (10 -5). Consequently, the low-l multipole moments in the CMB temperature map predict the value of the measured spatial curvature Ω k. On this basis we argue that a measurement of |Ω k| > 10 -4 would rule out slow-roll eternal inflation in our past with high confidence, while a measurement of Ω k < -10 -4 (which is positive curvature, a locally closed universe) rules out false-vacuum eternal inflation as well, at the same confidence level. In other words, negative curvature (a locally open universe) is consistent with false-vacuum eternal inflation but not with slow-roll eternal inflation, and positive curvature falsifies both. Near-future experiments will dramatically extend the sensitivity of Ω k measurements and constitute a sharp test of these predictions.

    Original languageEnglish (US)
    Article number029
    JournalJournal of Cosmology and Astroparticle Physics
    Issue number6
    StatePublished - Jun 2012


    • CMBR theory
    • ination

    ASJC Scopus subject areas

    • Astronomy and Astrophysics


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