What’s the biggest thing in the universe?  That would be a  cluster of quasars so large it would take a vehicle traveling at the speed of light 4 billion years to cross.

The structure, known as a Large Quasar Group, or LQG, is so massive scientists say it may challenge a fundamental principle of cosmology, laid out by Albert Einstein, which states that when viewed on a sufficiently large scale, the properties of the universe are the same for all observers.

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“While it is difficult to fathom the scale of this LQG, we can say quite definitely it is the largest structure ever seen in the entire universe,” astronomer Roger Clowes, with the University of Central Lancashire, said in a statement.

“This is hugely exciting, not least because it runs counter to our current understanding of the scale of the universe,” Clowes said.

At its widest point, the LQG is about 1,600 times greater than the distance between the Milky Way galaxy and its nearest neighbor, Andromeda, a span equal to about 2.5 million light-years, or 15 quintillion miles.

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The research has been published in the journal Monthly Notices of the Royal Astronomical Society.

Editor’s note: A previous version of this article stated that 2.5 million light-years equates to 15 trillion miles. As noted by some comments below, this number in fact equates to 1.5×1019 or 15 quintillion miles.

Image: The colored background indicates the peaks and troughs in the occurrence of quasars at the distance of the LQG. Darker colours indicate more quasars, lighter colors indicate fewer quasars. The LQG is clearly seen as a long chain of peaks indicated by black circles. (The red crosses mark the positions of quasars in a different and smaller LQG). The horizontal and vertical axes represent right ascension and declination, the celestial equivalent of longitude and latitude. The map covers around 29.4 by 24 degrees on the sky, indicating the huge scale of the newly discovered structure. Credit: R. G. Clowes / UCLan