How Isotropic is the Universe?

  title={How Isotropic is the Universe?},
  author={Daniela Saadeh and Stephen M. Feeney and Andrew Pontzen and Hiranya V. Peiris and Jason D. McEwen},
  journal={Physical review letters},
  volume={117 13},
A fundamental assumption in the standard model of cosmology is that the Universe is isotropic on large scales. Breaking this assumption leads to a set of solutions to Einstein's field equations, known as Bianchi cosmologies, only a subset of which have ever been tested against data. For the first time, we consider all degrees of freedom in these solutions to conduct a general test of isotropy using cosmic microwave background temperature and polarization data from Planck. For the vector mode… 

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