We Have No Idea: A Guide to the Unknown Universe

by Jorge Cham

Fairly recently we learned that the galaxies themselves are not distributed evenly throughout the universe. They tend to clump together into loose groups106 and clusters, which themselves group together into massive superclusters, each with dozens of clusters. Our supercluster weighs in at about 1015 times the mass of our Sun. Heavy stuff. So far, up to the scale of galactic superclusters, the structure of the universe is very hierarchical: moons orbit planets, planets orbit stars, stars orbit the center of galaxies, galaxies move around the center of their clusters, and the clusters zoom around the centers of superclusters. The strange thing is that it ends there. Superclusters don’t form megaclusters, superduperclusters, or uberclusters, but instead they do something much more surprising: they form sheets and filaments hundreds of millions of light-years across and tens of millions of light-years thin. These sheets of superclusters are impossibly vast structures, and they curve around to form irregular bubbles and strands that surround huge empty cosmic voids in which there are no superclusters or galaxies and very few stars, moons, or quintillionaires.