This is a computer simulation showing early structures which collapsed out of the rather smooth initial universe. The filamentary like structures also resemble "bubbles". These simulations try to match the kinds of structures seen in large scale galaxy surveys which show such bubbles or voids between large sheet-like structures of galaxies and galaxy clusters.

The density of matter in the region of space that now contains the Milky Way was perhaps 0.5% higher than in adjacent regions. Because its density was higher, this region of space expanded more slowly than surrounding regions. As a result of this slower expansion, its relative over-density grew. After a billion years of this slow expansion, our region of space was roughly twice the density of neighboring regions. This, about 1 billion years after the Big Bang, was the time in which galaxies formed, as seen in the most distant HST Deep Field.