Scientists Discovered an 'Ultra-Large Structure' in Space That Shouldn't Exist

Our universe is so big, it’s practically unimaginable. But there are massive structures within it that defy not just imagination but some of our foundational ideas about the universe.

Since the mid 1980s, astronomers have found huge connected clumps of galaxies that form clusters, walls, and threads sitting inside a kind of scaffolding called the cosmic web. Some of these structures are so immense that they shouldn’t exist according to one of the most fundamental principles in physics—the cosmological principle—which says that, if you zoom out far enough, all matter in the universe is spread out evenly.

As of 10 January, scientists added another of these ultra-large structures to the list, further pushing cosmologists to re-examine their assumptions about the nature of our universe. The structure, dubbed the Big Ring, was discovered by University of Lancashire PhD student Alexia Lopez and presented at the 243rd meeting of the American Astronomical Society this month. 

“It’s amazing. It’s surreal,” Lopez, who discovered another ultrastructure called the Giant Arc back in 2021, said in an interview with BBC News. 

The Big Ring is on par with other huge space structures astronomers have found before (measuring in at 1.3 billion light years across or 15 Earth moons) but dwarfed by the undisputed biggest structure, called the Giant GRB Ring, which clocks in at 5.6 billion light years in diameter. 

The newly-discovered ring lies roughly 9 billion light years from Earth, or about a fifth of the way to the edge of the observable universe, in the constellation of Boötes the Herdsman. The constellation is also home to the Giant Arc. 

The fact that there are two humongous structures within the same narrow region of space is one of the hints that the Standard Model of Cosmology—also known as ΛCDM, which includes assumptions such as the cosmological principle—might not explain everything about the universe. “Neither of these two ultra-large structures is easy to explain in our current understanding of the universe,” said Lopez in a press statement. “Their ultra-large sizes, distinctive shapes, and cosmological proximity must surely be telling us something important—but what exactly?”

Lopez and her colleagues have even speculated that the Giant Arc and Big Ring together form an even bigger structure. “Identifying two extraordinary ultra-large structures in such close configuration raises the possibility that together they form an even more extraordinary cosmological system,” she said. 

One possibility that could theoretically explain such structures is cosmic strings—cracks that formed very early on in the universe’s history after it finished its first sudden expansion. These cracks could form networks or loops which show up as ultra-large structures today.

Another possibility is that they’re explained by a totally different cosmological model, called Conformal Cyclic Cosmology. This theory states that, instead of the universe definitively starting with a Big Bang and ending with a Big Crunch, the universe goes through several cycles or aeons that don’t necessarily end with a crunch. Instead, matter just becomes more diluted until the universe tapers out and is then scaled back down to another Big Bang moment. Each aeon might leave behind traces, which may be ultra-large structures, of the one before.

Although this is a tantalizing prospect, the standard cosmological model is still the best explanation for our universe and everything in it. Whatever the explanation, which for now remains a mystery, Lopez is confident that we aren’t just seeing these structures by chance.

“Yes, we can expect some occasional flukes in the cosmic structure but we’re now finding this accumulating set of really, really big structures,” she told reporters at a press conference, adding that she also used independent data to verify her finding. 

Lopez, along with her colleague Roger Clowes and collaborator Gerard Williger from the University of Louisville, discovered the Big Ring by looking for super-bright and super-far-away lights called quasars using the Sloan Digital Sky Survey. These lights travel across the universe and through clouds of matter like galaxies. When they do, the galaxies show up as gaps in the measured quasar light. “The quasars act like spotlights in a dark room, highlighting where this intervening matter is,” Lopez explained. 

They can then combine this position information with measurements of how far away the galaxies are to get a 3D map of the Big Ring. In this 3D map, the ring actually appears a bit more like a corkscrew viewed head on.

The team still has more data to analyze, which might illuminate some answers or dredge up even more questions and even more structures. “Until I look through the rest of the data, I won’t know whether these are the only cases or if there are more structures out there like this,” said Lopez.