## Prominent and Subtle Manifestations of Persistent Probability Currents in Non-equilibrium Steady States

Royce Zia, Virginia Tech

For many interesting phenomena in nature, from all life forms to the global climate, the fundamental hypothesis of equilibrium statistical mechanics does not apply. Instead, they are perhaps better characterized by non-equilibrium steady states (NESS), evolving with dynamical rules which violate detailed balance and time reversal symmetry. In particular, such dynamics leads to the existence of non-trivial, persistent probability currents - a principal characteristic of NESS. In turn, these give rise to the notion of "probability angular momentum". Observable consequences of such abstract concepts will be illustrated in the context of simple pedagogical examples, showing both obvious and obscure manifestations. Applications to other systems, from tractable models of opinion formation to the complex behavior in our ocean heat content, will also be presented.