Final answer:
The distribution of galaxies on large scales follows a complex pattern of walls, voids, and filaments, which has likely been established since shortly after the universe began. Astronomical surveys like the Sloan Digital Sky Survey confirmed these structures. Theory suggests that the interplay between dark matter and gravity over time shaped these structures.
Step-by-step explanation:
The distribution of galaxies on large scales in the universe is not random. Instead, galaxies are structured into a complex pattern of walls, voids, and filaments. Galaxies, and in particular clusters of galaxies, tend to be found in the 'walls' of immense voids, with few galaxies within the voids themselves. These structures have likely been in place since shortly after the universe began its expansion 13.8 billion years ago. The cosmological principle asserts that on large scales, the universe is homogeneous and isotropic. However, concerning the detailed arrangement of galaxies, they are grouped together in clusters that, along with superclusters, fill only a minor fraction of space, being surrounded by large voids.
These findings are supported by large-scale astronomical surveys, such as the Sloan Digital Sky Survey. Theories of galaxy formation face the challenge of explaining how the nearly uniform distribution of matter in the early universe formed the intricate superclusters, clusters, voids, and filaments observed today. The interaction of dark matter, gravity, and time is critical in creating the structures we see in the current universe.