Currents in nonequilibrium statistical mechanics.

Nonzero currents characterize the nonequilibrium state in stochastic dynamics (or master equation) models of natural systems. In such models there is a matrix R of transition probabilities connecting the states of the system. We show that if the strength of a transition increases, so does the current along the corresponding bond. We also address the inverse problem: given a set of observed currents, we show the extent to which the original " R " can be recovered. These considerations lead to a general discussion of time scales and substance flows.