Small Scale Behavior of Cosmic String Networks
  The evolution of cosmic string networks is an interesting dynamical problem. The equations governing these networks are classical and fully specified, but the length scale at which cosmic string loops form has been uncertain to tens of orders of magnitude. Numerical simulations are limited in the range of length and time scales they can reach, while analytic methods have been limited by the nonlinearities of the problem. We describe a recent analytic scaling model developed in collaboration with Jorge Rocha and Florian Dubath which, together with recent simulations, appears to resolve this question. 
Joseph Polchinski