Relativistic hydrodynamics: connecting microscopic interactions to macroscopic collective motion

par Dr Rajeev Singh (Université Goethe de Francfort, Allemagne)

jeudi 5 nov. 2026, 14:00 → 15:00 Europe/Paris

Salle 1180, bâtiment E2 (Salle des séminaires )

Relativistic hydrodynamics provides a universal framework for describing the collective behavior of matter, from the quark-gluon plasma produced in heavy-ion collisions to astrophysical systems. Despite its broad applicability, formulating a theory of relativistic viscous fluids consistent with causality, stability, and thermodynamics remains a fundamental challenge. In this talk, I will introduce the basic principles of relativistic hydrodynamics, emphasizing conservation laws, dissipative effects, and the challenges of extending conventional fluid dynamics to relativistic systems. I will then discuss the freedom to redefine hydrodynamic variables, known as hydrodynamic frame transformations, and explain how different formulations can describe the same long-wavelength physics while exhibiting different non-hydrodynamic behavior. Finally, I will introduce density-frame hydrodynamics, a formulation that is first order in time and requires no additional dynamical fields. I will highlight its physical and computational advantages and discuss how it naturally lends itself to extensions involving thermal fluctuations, spin, and curved spacetime.