Broken detailed balance in active biological systems

Living systems function out of thermodynamic equilibrium. We present a method to identify such nonequilibrium dynamics based on broken detailed balance. Using this, we study active dynamics in beating flagella and non-periodic fluctuations of primary cilia. Finally, we show with a model how tracer laments can also be used to infer nonequilibrium dynamics in active networks. Specifically, the lament’s normal modes exhibit current cycles in phase space, revealing information about activity. This analysis may provide a general tool to quantify nonequilibrium dynamics in cells and tissues.