Original URL: http://www.theregister.co.uk/2013/01/14/large_quasar_group_billions_light_years/

Unbelievably vast quasar cluster forces universe-sized rethink

Hiding in plain sight: discovery came from public data

By Richard Chirgwin

Posted in Science, 14th January 2013 01:07 GMT

It’s there, but it shouldn’t be: the Sloan Digital Sky Survey has found a quasar cluster so large that it demands a re-assessment of theories about the universe.

The problem with the Large Quasar Group is this: it’s too big. One of the assumptions astronomers draw from Einstein’s General Theory of Relativity is that at the large scale, the universe should look uniform in every direction (to be more formal: on a sufficiently large scale, the properties of the universe are the same for all observers).

With its 73 members spanning four billion light years, the Large Quasar Group is a theoretical inconvenience, because astrophysical models have suggested that 1.2 billion light years was the upper limit for the size of a structure.

That limit was derived from computer modelling by a team led by Jaswant Yadav working at the Korea Institute for Advanced Study in 2010.

However, if you’re looking for an “Einstein wrong!” headline, The Register must disappoint you. As lead research in the study Roger 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].”

The team led by Clowes, an astronomer at University of Central Lancashire in England, used data publicly available from the Sloan Digital Sky Survey and New Mexico’s Apache Point observatory.

To get an idea of the scale of the four-billion-light-year monster, National Geographic points out that the Milky Way is around 100,000 light years across, and the Virgo Cluster (of which we’re a member) is just a hundred million light years wide.

Just how many London buses that measures, The Register will leave to its readers to work out. ®