Artist’s impression of a very distant quasar powered by a black hole with a mass two billion times that of the Sun. (Image: ESO/M. Kornmesser via Wikimedia Commons)

Scientists have found the largest known structure in the universe, a cluster of galactic cores so vast it would take four billion years for a spacecraft traveling at the speed of light to cross it.

The sighting challenges a theory from Einstein which suggests such a massive object shouldn’t exist in the universe.

A quasar is the compacted center of a galaxy surrounding a massive black hole from the early days of the universe.  Quasars  go through periods of extreme brightness which can last anywhere from 10 to 100 million years. They tend to band together in enormous clusters, or structures, forming large quasar groups (LQGs).

The international group of scientists led by Roger Clowes from the University of Central Lancashire’s Jeremiah Horrocks Institute, used data from the Sloan Digital Sky Survey (SDSS), a major surveying project that uses 2.5-m wide-angle optical telescope located at New Mexico’s Apache Point Observatory, to make their findings.

Clowes and his colleagues are astounded by the size of this structure, which defies the Cosmological Principal, based on Albert Einstein’s theory of General Relativity that assumes when you look at the universe from a sufficiently large scale; it looks the same no matter where you are observing it from.  The Cosmological Principle, according to the research team, is assumed but has never been demonstrated observationally ‘beyond reasonable doubt.’

Large quasar group (LQG) as imaged by the Big Throughput Camera at the Cerro Tololo Inter-American Observatory in Chile (Photo: Chris Haines)

“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,” said Clowes. “This is hugely exciting, not least because it runs counter to our current understanding of the universe. The universe doesn’t seem to be as uniform as we thought.”

Clusters of galaxies can be anywhere from six to 10 million light-years across, but the LQGs can be 650 million light-years or more across. Making calculations based on the Cosmological Principle, along with the modern theory of cosmology, astrophysicists shouldn’t be able to find a structure in the universe larger than 1.2 billion light-years, much less four billion light-years across as this newly sighted structure is.

To get some additional perspective of what the astronomers found, let’s step back and give it a sense of scale.  Our own galaxy, the Milky Way, is separated from its nearest neighbor, the Andromeda Galaxy, by a distance of 2.5 million light-years.

Clowes points out that his team’s discovery does have a typical dimension of 1.6 billion light-years. But, because it is elongated, its longest dimension is four billion light-years, making it about 1,650 times larger than the distance from the Milky Way to Andromeda.

An artist’s drawing shows a large black hole pulling gas away from a nearby star. (NASA)

Of all the celestial objects that make up the Universe, nothing is more mysterious than the black hole.

Now Denmark scientists have come up with what they say are groundbreaking theories that explain several properties of the enigmatic black hole.  The scientists’ research indicates black holes have properties similar to the dynamics of both solids and liquids.

Albert Einstein- circa 1921 (Photo: Creative Commons/Wikipedia)

What’s generally known about black holes is that they’re extremely compact  –some are as small as less than .01 mm– and that they can generate a gravitational pull so powerful that anything and everything that comes near them is swallowed up, including light.

We’re not able to see these cosmic vacuum cleaners because any light that does hit them is absorbed rather than being reflected. Black holes were predicted by Einstein’s general theory of relativity but scientists haven’t been able to determine their properties.

“Black holes are not completely black, because we know that they emit radiation and there are indications that the radiation is thermal, i.e. it has a temperature,” explains Niels Obers, a professor at the University of Copenhagen.

Obers says one can view black holes like particles. Since, in principle, a particle has no dimensions, it is merely a point. But, if a particle is given an extra dimension –such as a straight line– it then becomes a string.  And if you give the string yet an additional dimension, it becomes a plane. Physicists refer to one of these planes as a ‘brane’, similar to the biological term, ‘membrane’.

“In string theory, you can have different branes, including planes that behave like black holes, which we call black branes,” Obers says. “The black branes are thermal, that is to say, they have a temperature and are dynamical objects. When black branes are folded into multiple dimensions, they form a ‘blackfold’.”

Artist impression of black branes forming a “blackfold”(Artist impression by Merete Rasmussen)

Obers and his colleagues say they’ve been able to develop their new theories on the physics of black holes based on the principals of these black branes and blackfolds.

“The black branes are hydro-dynamic objects, that is to say that they have the properties of a liquid,” says Jay Armas, who also worked on the project. “We have now discovered that black branes also have properties which can be explained in terms of solids. They can behave like elastic material when we bend them.”

“With these new theories, we expect to be able to explain other black hole phenomena, and we expect to be able to better understand the physical properties of neutron stars,” said Obers.