112 Chapter 4: Fluctuations in Jet Tomography gated through a medium evolved through hydrodynamics found that energy loss using the ASW quenching weights in conjunction with up-to-date exper- imental results are in fact not fragile, either [396]. The pion R$_{AA}$ ( p$_{T}$ ) then has the potential to be a quite good experimental signal for jet tomographic studies at $_{Rhic}$. However the large systematic theoretical error seen in Fig. 4.9 associated only with changes in the coupling raise serious doubts about the theoretical imprecision of calculated results. Before any firm conclusions may be made regarding the possibility of tomography these issues must be more rigorously investigated. We show in Fig. 4.12 the large qualitative difference in p$_{T}$ dependence for predicted Lhc pion R$_{AA}$ from the WHDG model and from two different im- plementations of the ASW model; one easily sees the dramatic rise in R$_{AA}$ with increasing p$_{T}$ from the first as opposed to the flat in p$_{T}$ results of the latter two. The consistency of Vitev’s curve [397] with ours over a range of dN$_{g}$/dy and the consistency of the two ASW calculations [296, 306] suggest that this will be a robust test of the energy loss mechanisms. The origin of the difference can be easily understood given our discussion of Rhic results. For the case of WHDG, the pion R$_{AA}$ at Rhic does not require much over- absorption. The modest increase in medium density, ∼ 2 − 3 based on either an extrapolation of Phobos results [398, 399] or predictions from the CGC 4.6 LHC Predictions