January 13th, 2013 by James Ayre
The largest known structure in the universe has just been discovered, and is so large that it completely violates a number of widely-accepted theories. It’s a large quasar group (LQG), that’s so enormous that it would take someone traveling at the speed of light at least four billion years to completely pass through it.
The discovery, made by an international group of researchers being led by the University of Central Lancashire, seems to directly contradict Einstein’s 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.” Of course, the theory could still hold true, but it would involve ‘observing’ the universe on a much larger scale than we do.
“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’.”
For a better understanding of the scale of this thing; “our galaxy, the Milky Way, is separated from its nearest neighbour, the Andromeda Galaxy, by about 0.75 Megaparsecs (Mpc) or 2.5 million light-years.”
“Whole clusters of galaxies can be 2-3 Mpc across but LQGs can be 200 Mpc or more across. 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.”
The newly found LQG has a ‘typical’ dimension of 500 Mpc. Which is already much larger on its own, but “because it is elongated, its longest dimension is 1200 Mpc (or 4 billion light years) — some 1600 times larger than the distance from the Milky Way to Andromeda.”
As Dr Clowes says: “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. This is hugely exciting — not least because it runs counter to our current understanding of the scale of the universe.”
‘Even travelling at the speed of light, it would take 4 billion … years to cross. This is significant not just because of its size but also because it challenges the Cosmological Principle, which has been widely accepted since Einstein. Our team has been looking at similar cases which add further weight to this challenge and we will be continuing to investigate these fascinating phenomena.”
“Quasars are the nuclei of 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 known that quasars tend to group together in clumps or ‘structures’ of surprisingly large sizes, forming large quasar groups or LQGs.”
The new discovery was just detailed in an article published in the journal Monthly Notices of the Royal Astronomical Society.
Here’s some more information on Quasars:
“A quasi-stellar radio source (‘quasar’) is a very energetic and distant active galactic nucleus. Quasars are extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than extended sources similar to galaxies.”
“While the nature of these objects was controversial until as recently as the early 1980s, there is now a scientific consensus that a quasar is a compact region in the center of a massive galaxy surrounding its central supermassive black hole. Its size is 10–10,000 times the Schwarzschild radius of the black hole. The quasar is powered by an accretion disc around the black hole.”
Image Credits: R. G. Clowes / UCLan; Quasar via Wikimedia C
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