Length Scales and Dynamics in Contractile Active Gels

Most materials deform when external stresses are applied. This paradigm is familiar to sculptors who deform clay to produce structures. However, living materials such as cells and embryos are capable of deforming on their own. Contractile active gels of the proteins actin and myosin are one of the main drivers of force generation in biology. Here I will present experiments that characterize the length-scale behavior of active gel contraction, which find evidence for critical behavior. I will then present experiments that characterize the dynamics of active gel contraction, which identify dynamic precursors to contraction.