77 Chapter 3: v$_{2}$ vs. R$_{AA}$ as a Constraint on sQGP Dynamics partons must be made sensitive to the medium. Then the anisotropy of the background created by noncentral$_{Rhic}$ collisions translates into anisotropy of the jets. However, this sensitivity to the medium also leads to jet attenuation and a decrease in R$_{AA}$ . As we will see, the very high v$_{2}$ values measured at Rhic mean that, at best, previous models either oversuppressed R$_{AA}$ or underpredicted v$_{2}$ . Hydrodynamics has been applied to the low- p$_{T}$ particles with great success. Unfortunately, the lack of thermal equilibrium precludes the use of hydrody- namics in the momentum regime we are interested in. Moreover, a na¨ıve application would highly oversuppress R$_{AA}$ due to the Boltzmann factors. Parton transport theory attempts to extend hydrodynamics’ range of ap- plicability to higher transverse momenta [135, 138]. The M´ olnar parton cas- cade (MPC) succeeded in describing the low- and intermediate- p$_{T}$ v$_{2}$ results of Rhic only by taking the parton elastic cross sections to be extreme, σ$_{t}$ ∼ 45 mb [138]. Even more damning, we will show that the MPC approach reaches the reported v$_{2}$ values at the expense of reproducing the experimental R$_{AA}$ data. pQCD becomes valid for moderate and higher p$_{T}$ partons, and models based on pQCD calculations of radiative energy loss have had success in re- producing the experimental R$_{AA}$ ( p$_{T}$ ) data [356]. These models use a single, representative pathlength; as such, they give v$_{2}$ ≡ 0. Compelling but not convincing, past geometric approximations of energy loss sought to demonstrate the inability of pure jet quenching to match the