Second-order relativistic fluids break conservation laws

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Written by Vojtěch Witzany

Higher-order fluids are fluids which have higher-order gradient terms in their stress-energy tensor. It is well established that at least second-order fluids are needed for a causal relativistic theory of dissipation. Furthermore, the question of even higher-order fluids arose recently in the context of the AdS/CFT correspondence where the higher-order fluid dynamics emerge as an effective-field description of the conformal field on the boundary. In this talk, we will deliver a simple theoretical argument which suggests that, starting with order 2, effective higher-order fluid descriptions must generically break conservation of the stress-energy tensor and the conservation of Noether currents.