The initial data of effective field theories of relativistic viscous fluids and gravity - arXiv
arxiv.org
A new arXiv paper tackles one of the deepest puzzles in theoretical physics: whether relativistic viscous fluids coupled to gravity even have well-posed initial conditions — and the answer hinges on which mathematical "frame" you choose.
Effective Field TheoryRelativistic HydrodynamicsCausal StructureInitial Value Problem
Theory Briefing
- BDNK theory uses second-order time derivatives, making initial data specification fundamentally different from the Landau-frame formulation.
- Effective field theories of relativistic viscous fluids must be coupled to gravity to properly define causal, well-posed initial value problems.
- The choice of hydrodynamic frame — BDNK vs. Landau — isn't just a gauge choice; it physically changes which initial data is admissible.