Caltech scientists have developed new models of the universe that account for the recent finding that temperature variations in the cosmic microwave background radiation over half the sky appear to be about 10 percent greater than the variations in the other half.

In one scenario, the universe existed before inflation — the short-lived but enormous growth spurt associated with the Big Bang. In the other scenario, the universe is but a tiny part of a primordial structure now grown so big it exceeds the horizon of the observable universe.