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Viscosity in Strongly Interacting Quantum Field Theories from Black Hole Physics

P. Kovtun·D. T. Son·A. O. Starinets
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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 $\hbar/4πk_B$ 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.

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P. Kovtun, D. T. Son, A. O. Starinets. 2005-03-17. Viscosity in Strongly Interacting Quantum Field Theories from Black Hole Physics. https://doi.org/10.1103/physrevlett.94.111601

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