121 Chapter 5: pQCD vs. AdS/CFT calculations relative to Stefan-Boltzmann, (2) the order of magnitude reduc- tion of the viscosity to entropy ratio η/s predicted relative to pQCD needed to explain the seemingly near perfect fluid flow of the sQGP observed at $_{Rhic}$, (3) the unexpectedly large stopping power of high transverse momenta heavy quarks as inferred from heavy quark jet quenching, see Fig. 5.1, and elliptic flow, and (4) the possible occurrence of conical “Mach” wave-like correlations of hadrons associated with tagged jets. While quantitative and systematic comparisons of AdS/CFT gravity dual models with nuclear collision data are still incomplete and while the conjec- tured double Type IIB string theory ↔ conformal Supersymmetric Yang-Mills (SYM) gauge theory ↔ non-conformal, non-supersymmetric QCD correspon- dence remains under debate (see, e.g. [433]), the current successes provide strong motivation to seek more sensitive experimental tests that could help guide the theoretical development of novel theoretical approaches that may be needed to explain recent Rhic and soon Lhc heavy ion data. The aim of this chapter is twofold. First is to propose a robust observable that can more readily reveal the kinematic boundaries and reaction conditions where specific Standard Model weak coupling pQCD approximations may fail and where specific strong coupling AdS/CFT approximations may fail (or if they are applicable at all). Asymptotic freedom and the factorization theorems of QCD ensure that pQCD should apply above some hard scale Q ( A, √ s ) that depends in general on both atomic number, A , and center of mass energy, √ s . For jet production this scale is the greater of the gluon saturation scale