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Cosmology

Designs for an asymmetric universe

Nature Physics volume 5, pages 89–90 (2009)Cite this article

Puzzling anisotropies in the cosmic microwave background radiation across the sky are leading some researchers to contemplate cosmology in an asymmetric universe.

At the same time there are puzzling features of the temperature maps that threaten to undermine confidence in the simplest models of inflation. The WMAP team themselves identified a surprising absence of correlations between temperature anisotropies on the largest angular scales2 — surprising if the quantum fluctuations produced by the inflationary expansion are close to scale-invariant. Subsequent analyses found unexpected alignment of the lowest multipole moments of the temperature anisotropies, which has been dubbed “the axis of evil”3. The statistical significance of these anomalies is tricky to assess because we have only a small number of independent measurements of the correlations on large angular scales — and cosmologists have only one universe to observe. We have, for example, only five independent components of the quadrupole moment on our microwave background sky, and predictions based on any given realization of a random distribution have an intrinsic 'cosmic variance', which is large if we have only a small number of observables.

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Figure 1: Anisotropy in the cosmic microwave background radiation.

NASA/COBE/DMR NASA/WMAP SCIENCE TEAM

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Authors and Affiliations

  1. David Wands is at the Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth PO1 3FX, UK. david.wands@port.ac.uk,

    David Wands

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Wands, D. Designs for an asymmetric universe. Nature Phys 5, 89–90 (2009). https://doi.org/10.1038/nphys1195

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