For decades, cosmologists have wondered if the large-scale structure of the universe is a fractal — that is, if it looks the same no matter how large the scale. After completing massive surveys of galaxies, scientists finally have an answer: No, but kind of, in a way.

In the early 20th century, astronomers — beginning with Edwin Hubble and his discovery of the enormous distance to Andromeda, the closest galaxy to our own Milky Way — started to realize that the universe is almost unimaginably vast. They also learned that we can see galaxies scattered about, both near and far. And so, naturally, a question arose: Is there any sort of pattern to the arrangement of those galaxies, or is it totally random?

At first, it looked random. Astronomers saw giant galaxy clusters, each containing a thousand or more galaxies. And there were also much smaller groups of galaxies, and galaxies hanging out by themselves. Taken together, the observations made it appear as if there were no overarching pattern to the cosmos.

And astronomers were fine with that. They had long assumed an idea called the cosmological principle — that is, that the universe is mostly homogeneous (roughly the same from place to place) and isotropic (roughly the same no matter which direction you look). A bunch of random galaxies and clusters fit right into that principle.

But in the late 1970s, galaxy surveys became sophisticated enough to reveal the beginnings of a pattern in the arrangement of galaxies. Besides the clusters, there were also long, thin filaments of galaxies. There were broad walls. And then there were the voids — vast expanses of nothing. Astronomers called it the cosmic web. This pattern would violate the cosmological principle, because it would mean that large regions of the universe did not look like other large regions of the universe.

So perhaps there was more to the story.