Richard McCray (JILA, University of Colorado)

The best scientific model of our cosmic origin is known as the Big Bang. According to this model, the universe was incredibly hot—billions of degrees in every direction—a few minutes after the universe first began to expand. After about half a million years, the cosmos cooled enough for matter and energy to separate, creating the cosmic microwave background radiation (CMBR). All of the large-scale structure in the universe began from fluctuations in the temperature in the CMBR. In the 1990's, astronomers used the Cosmic Background Explorer Satellite (COBE) to show that the CMBR was almost, but not quite, perfectly smooth (smooth to one part in a hundred thousand). This is akin to a sheet of glass the size of a football field with bumps only as big as grains of sand.

The cosmic web

According to astronomical theories, these tiny variations in the CMBR are manifestations of very slight fluctuations in the density of matter in the early universe. Over billions of years, gravity attracts the matter toward regions of slightly elevated density, and this process becomes amplified as these regions become more dense. Astronomers call this process gravitational instability and suspect that this process will amplify the barely-perceptible fluctuations that we see in the early universe into the giant structures (voids and superclusters) that we see in the universe today. In this movie, we fly around and through a cube of space many millions of light-years across. The web-like structures in this space trace the distribution of matter; the intersection points of the web are the locations of galaxies, clusters, and superclusters—the densest concentrations of matter in the universe.

Austin Reiter