Black Holes, Black Branes and Blackfolds

Posted on December 11, 2012

Blackfold


Researchers have come up with new theories they say explain some of the properties of black holes. It is known that black holes are so extremely compact that they create an incredibly powerful gravitational pull that swallows up everything that comes near them, including light. However, black holes do emit radiation. It has also become known that black holes are common in the universe.

Niels Obers, a professor of theoretical particle physics and cosmology at the Niels Bohr Institute at the University of Copenhagen, said in a release, "But 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."

The "black hole" concept has become mainstream. There are also less commonly known - and more complex concepts - like black branes and blackfolds. An artist's impression of a blackfold is pictured above.

Niels Obers builds theoretical models to better understand black hole physics. Obers says, "You can look at a black hole like a particle. A particle has in principle no dimensions. It is a point. If you give a particle an extra dimension, it becomes a string. If you give the string an extra dimension, it becomes a plane."

Physicists call this plane a "brane." Obers explains that there are different kinds of branes in string theory.

Obers says, "In string theory, you can have different branes, including planes that behave like black holes, which we call black branes. 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'."

Niels Obers and his two doctoral students Jay Armas and Jakob Gath have discovered that black branes behave like elastic material when they are bent.

Armas says, "The black branes are hydro-dynamic objects, that is to say that they have the properties of a liquid. 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."

Armas also says there is a piezoelectric effect when black branes are bent and folded to form a blackfold. The researchers also say a blackfold has a relationship between gravity and fluid mechanics and solid-state physics.

The researchers say, "This new effect can be understood as a slightly bent and charged black string with a greater concentration of electric charge on the innermost side in relation to the outermost side. This produces two electrically charged poles on the black strings. Black holes are predicted by Einstein's theory of gravity. This means that there is a very surprising relationship between gravity and fluid mechanics and solid-state physics."

The researchers say that with these new theories they expect to be able to explain other black hole phenomena. The research was published here in the journal, Physical Review Letters.

Image: Artist impression by Merete Rasmussen