title: First observational tests of eternal inflation.
abstract: The eternal inflation scenario predicts that our observable Universe resides inside a single bubble embedded in a vast inflating multiverse. We present the first observational tests of eternal inflation, performing a search for cosmological signatures of collisions with other bubble universes in cosmic microwave background data from the WMAP satellite. We conclude that the WMAP 7-year data do not warrant augmenting the cold dark matter model with a cosmological constant with bubble collisions, constraining the average number of detectable bubble collisions on the full sky N(s) < 1.6 at 68% C.L. Data from the Planck satellite can be used to more definitively test the bubble-collision hypothesis.
authors: Department of Physics and Astronomy, University College London, United Kingdom. stephen.feeney.09@ucl.ac.uk
authors: Stephen M
authors: SM
authors: Feeney
authors: Matthew C
authors: MC
authors: Johnson
authors: Daniel J
authors: DJ
authors: Mortlock
authors: Hiranya V
authors: HV
authors: Peiris