Relativistic fluids with spin

We study the behavior of relativistic fluids with internal angular momentum, using the tools of quantum mechanics and statistical mechanics to find out the general properties of macroscopic systems. We found that, if we consider thermodynamics, different couples of stress-energy and spin tensors (previously considered equivalent) give different predictions on the momentum and angular momentum density. This difference remains even in the non-relativistic limit and can in principle be measured experimentally.