Cosmology’s Lumpiness Problem Defies Theory

A record-breaking structure in the universe “defies theory,” the news said, ignoring that theory has been defied for decades since smaller large structures were found (the lumpiness problem).

PhysOrg‘s article begins with an image of it. It’s 4 billion light-years across, Science Daily‘s headline reads. And National Geographic led off with: “Biggest Thing in Universe Found—Defies Scientific Theory.” What is it? a huge Large Quasar Group (LQG), found in data from the Sloan Digital Sky Survey.

Talk about a whopper—astronomers have discovered a structure in the universe so large that modern cosmological theory says it should not exist, a new study says.

Well, then, will they junk theory and start over? Roger Clowes confessed, “It could mean that our mathematical description of the universe has been oversimplified—and that would represent a serious difficulty and a serious increase in complexity.” Nobody seems ready, however, to jump ship, even with the confessions:

• “This structure is bigger than we expect based on the shockwaves formed in the universe after the big bang,” said [Gerard] Williger.
• “This discovery was very much a surprise, since it does break the cosmological record as the largest structure in the known universe,” said study leader Roger Clowes, an astronomer at University of Central Lancashire in England.
• So this represents a challenge to our current understanding and now creates a mystery—rather than solves one,” Clowes said.
• One theory holds that this type of colossal collection of quasars may be precursors to galaxy superclusters in the modern universe—but the exact nature of their connection is still a mystery.

Theory will survive because they need it to solve other problems. National Geographic speculates,

….the massive structure could possibly shed light on the evolution of galaxies like our own Milky Way. Quasars, which pump out powerful jets of energy, are among the brightest and most energetic objects from when the universe was still young. They represent an early, but brief, stage in the evolution of most galaxies.

—not that anyone has seen that happen, but it fits with theory.

The Lumpiness Problem in cosmology is old.* PhysOrg writes, “Since 1982 it has been known that quasars tend to group together in clumps or ‘structures’ of surprisingly large sizes, forming large quasar groups or LQGs.” Geller and Huchra threw down the first challenge in 1989 with their discovery of a “Great Wall” of galaxies. This LQG is so big, though, that big bang theory cannot deal with it. It spans 1/20 the observable universe. That’s 500 Mpc (megaparsecs), far exceeding the limit of theory: “Based on the Cosmological Principle and the modern theory of cosmology, calculations suggest that astrophysicists should not be able to find a structure larger than 370 Mpc.” Well, now they do.

The team, led by Dr Roger Clowes from UCLan’s Jeremiah Horrocks Institute, has identified the LQG which is so significant in size it also challenges the Cosmological Principle: the assumption that the universe, when viewed at a sufficiently large scale, looks the same no matter where you are observing it from.

New Scientist says the trend to find larger and larger structures has been ongoing:

“As time went on, people did more and more surveys,” says Clowes. “Each time they found structures the size of the new survey, and you began to wonder when it would all stop.“

Previous calculations gave a value of one billion light years as the maximum possible size of a cluster. The 1991 LQG is at this supposed limit, but Huge-LQG smashes right through it. The researchers say this could undermine the cosmological principle, although it may simply mean that we need to revise upwards the size limit on large structures.

Aha—that suggests that theory can be rescued with a revision, something like raising the national debt ceiling. But the Huge-LQG is not the only crisis: a controversial stream of galaxies all moving in the same direction, called the “dark flow,” also flies in the face of theory.

Getting from a smooth beginning to a universe of structure has long proved a challenge to modern cosmology. Now, at the other end of the problem, according to another article on Science Daily, spacetime is “a smoother brew than we knew.” It’s not foamy like beer, but smooth like whiskey, the reporter quipped. So how does one get from a smooth spacetime, and a cloud of expanding gas, to dense clusters of dense matter in long chains of quasars? If it was hard to imagine in 1982, it’s much worse now.

The responses of some cosmologists are instructive.  Reporter Jacob Aron at New Scientist ends with these:

The search for such large structures is key to furthering our understanding of the universe and creating new and improved cosmological models, says Subir Sarkar of the University of Oxford. “All of this suggests there is structure on scales at which the universe is supposed to be boring,” he says.

But the cosmological principle is so ingrained that it is hard for researchers to shake. “People are maybe understandably reluctant to give up the thing, because it will make cosmology too bloody complicated,” says Sarkar.

In the NG article, Gerard Williger opined about what it would take to replace current theory:  “There is very likely some mechanism [that] is turning on quasars over a large scale like this—and in a short time—which could relate to some condition in the early universe.” With that, the cosmologists, briefly awakened from their dogmatic slumbers, rolled over and went back to sleep.

*For previous entries on the Lumpiness Problem, see 11/10/2000, 6/05/2001, 8/22/2001, 10/24/2003, 1/02/2004, 6/12/2008, or search on “lumpiness” in the Search Bar.

Try that kind of language in government to explain to a Congressional committee an unexpected expense doubling the limit of funding. “There is very likely some mechanism that could relate to some condition in the early accounting.”

So is the big bang falsified? The Huge-LQG “broke through” the limit set by theory. That should account for falsification. Can we move on now to design theories? The universe isn’t boring any more. It’s downright exciting. It’s far more complex than the secular consensus had “oversimplified.” Let the evidence speak, and get to work.