119 Chapter 5 pQCD vs. AdS/CFT Tested by Heavy Quark Energy Loss 5.1 Introduction Recent discoveries at$_{Rhic}$ [77, 104, 375, 405] have led to suggestions [335, 406– 414] that the properties of strongly coupled quark gluon plasmas (sQGP) produced in ultra-relativistic nuclear collisions may be better approximated by string theoretic models inspired by the AdS/CFT gravity-gauge theory correspondence [312, 415, 416] than conventional Standard Model perturba- tive QCD (pQCD). Four main classes of observables have attacted the most attention: (1) Entropy production as probed by multiplicity distributions [398], (2) “Perfect” Fluidity [405] as probed by collective elliptic flow ob- servables [106, 121, 138, 417–421], (3) Jet Quenching and Tomography as probed by high- p$_{T}$ hadrons [192, 277, 297, 373, 422] and nonphotonic lep- tons [237, 423, 424], and (4) Dijet-Bulk Correlations as probed by two and three particle correlations [425–431].