An international team led by academics from the University of Central Lancashire (UCLan) has found the largest known structure in the universe. The large quasar group (LQG) is so large that it would take a spacecraft traveling at the speed of light some 4 billion years to cross it.

Quasars are galaxies from the early days of the universe that undergo brief periods of extremely high brightness that make them visible across huge distances. These periods are ‘brief’ in astrophysics terms but actually last 10-100 million years.

Since 1982 it has been know that quasars tend to group together in clumps or ‘structures’ of surprisingly large sizes, forming large quasar groups or LQGs.

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 Cosmological Principle is the assumption that the universe, when viewed at a sufficiently large scale, looks the same no matter where you are observing it from.

The modern theory of cosmology is based on the work of Albert Einstein, and depends on the assumption of the Cosmological Principle. The Principle is assumed but has never been demonstrated observationally ‘beyond reasonable doubt’.

To give some sense of scale, our galaxy, the Milky Way, is separated from its nearest neighbour, the Andromeda Galaxy, by about 2.5 million light-years.