The Theory of Cosmic Inflation

cosmic inflation is the idea that in the very first moments of the universe, all these identical patches of the universe were very, very close together. They then wished apart expedientially fast, a moment of expansion that would have taken in a trillionth of a trillionth  of a second. Those then got locked in, so that to day, when we look at them, they still seem nearly identical even though they are half way across the universe from each other.