Biggest Structure In Universe Found, Raises Serious Cosmological Questions

A newly discovered colossal celestial structure is much bigger than astronomers thought possible, a revelation that is challenging some assumptions scientists had held about the universe.

In a paper published on Friday in the Monthly Notices of the Royal Astronomical Society, a scientific team led by University of Central Lancashire researchers described what they’ve dubbed the Huge Large Quasar Group, or Huge-LQG. The structure is a grouping of 73 quasars -- very energetic galactic nuclei powered by supermassive black holes -- that measures an estimated 4 billion light years across.

It’s hard to convey just how huge this quasar group is. At its widest, the structure is equal in breadth to 1,600 times the distance between our Milky Way galaxy and the neighboring Andromeda Galaxy.

The find challenges a previous assumption that estimated structures in the universe could get no larger than 1.2 billion light years across. That size limit was derived from a model published in 2010, as part of an attempt to flesh out the “cosmological principle,” which basically says that on a large scale, the universe looks the same in all directions for any observer -- not so much in terms of physical structures being exactly the same, but in that the physical laws we’re familiar with in our corner of the galaxy are fairly constant.

“Our cosmological model is based on the assumption that homogeneity applies,” lead author Roger Clowes told the Space Reporter on Saturday. “In the past when we’ve discovered large structures, we haven’t had to worry too much, because we’ve had lots of scope to increase the scale of homogeneity. But with this new structure, we’re running out of room in which to maneuver in this way.”

A vast structure like the Huge-LCG could violate the assumed homogeneity of the universe because it is such an outlier when compared to other structures in space. It’s also an unusual find, given what we thought we knew about how the expansion of the universe limits the size of large clumps of matter.

This is not to say that the discovery of the Huge-LQG means Albert Einstein slipped up at some point.

“It’s not the theory that’s a problem -- it’s the assumption of the cosmological principle,” Clowes told Space Reporter. “The assumption makes the math a lot easier, but if it turns out we have to drop the assumption, then we certainly don’t have to drop Einstein’s [theory of general relativity].”

SOURCE: Clowes et al. “A structure in the early Universe at z~1.3 that exceeds the homogeneity scale of the R-W concordance cosmology.” MNRAS published online 11 January 2013.