title: Viscosity in strongly interacting quantum field theories from black hole physics.
abstract: The ratio of shear viscosity to volume density of entropy can be used to characterize how close a given fluid is to being perfect. Using string theory methods, we show that this ratio is equal to a universal value of variant Planck's over 2pi/4pik(B) for a large class of strongly interacting quantum field theories whose dual description involves black holes in anti-de Sitter space. We provide evidence that this value may serve as a lower bound for a wide class of systems, thus suggesting that black hole horizons are dual to the most ideal fluids.
authors.affiliation: Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106, USA.
authors.forename: P K
authors.initials: PK
authors.lastname: Kovtun
authors.forename: D T
authors.initials: DT
authors.lastname: Son
authors.forename: A O
authors.initials: AO
authors.lastname: Starinets