  Recently, different proposals have been put forward on how thermalization
proceeds in heavy-ion collisions in the idealized limit of very large nuclei at
sufficiently high energy. Important aspects of the parametric estimates at weak
coupling may be tested using well-established classical-statistical lattice
simulations of the far-from-equilibrium gluon dynamics. This has to be
confronted with strong coupling scenarios in related theories based on
gauge-string dualities. Furthermore, closely related questions about
far-from-equilibrium dynamics arise in early-universe cosmology and in
non-relativistic systems of ultracold atoms. These were central topics of the
EMMI Rapid Reaction Task Force meeting held on December 12-14, 2011, at the
University of Heidelberg, which we report on.
