Chaotic inflationary theory is a highly speculative cosmological model in which many distinct universes form from different regions of a mother universe, with some inflating (see inflationary model) and others perhaps not. Our own universe, according to this idea, grew out of a quantum fluctuation in a pre-existing region of a much larger spacetime. Other universes, by the same token, could do the same from regions within our universe today. A new universe, or baby universe, which formed by this budding process, would have its own set of physical laws, material particles, and, possibly, life – entirely unlike anything with which we are familiar.

 

One reason for the possible appeal of the chaotic evolutionary model has to do with the anthropic principle. The multitude of resulting universes would have all possible values of the fundamental parameters. This would remove the need for "fine tuning" to make our universe habitable: we happen to live in one of the relatively few biological universe that exist in the multiverse – the infinite ensemble of all possible worlds.