We just finished a study demonstrating a way to use time-resolved RIXS to measure the collective exctiations of quantum materials, in this instance CDW-ordered La2-xBaxCuO4 (LBCO). The idea is to weakly perturb the system with a pump pulse and then measure the time evolution of the order parameter, which encodes the collective excitations of the system. The advantage of this technique is that the energy information comes from the time dynamics in a Fourier sense, allowing one to achieve extraordinarily high, sub-meV resolution. We found that the excitations in LBCO are overdamped and propagate diffusively, exhibiting dynamic critical scaling analogous to that observed in Oswald ripening in metal alloys in the 1980’s. The study, which was a collaboration with Nigel Goldenfeld’s group done at the new LCLS free electron laser facility at SLAC, was published in Science Advances.