33 Chapter 2: Motivation finite formation time effects were large and persisted far beyond the expected single Debye length. Consideration of only the elastic pole contributions by Adil et al. [245] reproduced the intuitive result; subsequent work by Gossiaux et al. [246] confirmed this. Djordjevic tackled the problem from a quantum mechanical standpoint and came to the same conclusion [247]. Nevertheless, the effects of finite time and off mass-shell creation are still under investigation [248]. Svetitsky [231] was the first to include fluctuations about the mean in elastic energy loss; he employed the Fokker-Planck equation. Moore and Teaney [249] thoroughly investigated the relativistic Langevin and Fokker- Planck equations in heavy ion collisions. This work was applied to heavy quark energy loss with additional nonperturbative mesonic resonances by Rapp and van Hees [250]. As shown by Wicks, however, for the pathlengths and densities at Rhic and Lhc the number of 2 → 2 collisions is of order a few, and the Gaussians resulting from these applications of the Central Limit Theorem are not a good approximation to the elastic energy loss distribution [243]. Rigorously deriving radiative energy loss is a tough business. Even in Abelian QED tremendous effort and theoretical contortions (‘reinterpretation’) were required to satisfactorily deal with the infrared and ultraviolet divergences (c.f., e.g., [251]). Undaunted, a number of nuclear theorists have devoted their lives to conquering nonabelian QCD radiative bremsstrahlung. The formalisms 2.2.4 Background Radiation