Universe may be mere bubble in greater multiverse

New Scientist : A puzzling asymmetry in the cosmic microwave background (CMB)—thermal radiation left over from the Big Bang—was discovered by the Wilkinson Microwave Anisotropy Probe and confirmed by the Planck satellite: Temperature fluctuations in one half of the sky differ in amplitude from those in the other half. To explain how such an asymmetry can occur without violating the homogeneity of the universe, Andrew Liddle of the University of Edinburgh in the UK and colleagues have woven together two earlier theories. They propose that our universe started as a relatively small bubble in a greater multiverse and that when the Big Bang occurred, small variations in the consistency of matter were carried along as if on an ocean wave. Whether or not there is anything beyond our own bubble of a universe has yet to be proved, however.