Violation of energy conditions and initial entropy bound in holographic Bjorken flow

We show that a Bjorken expanding strongly coupled $mathcal{N}=4$ Supersymmetric Yang-Mills plasma can violate the dominant and also the weak energy condition in its approach to hydrodynamics (even though the chosen initial data satisfy these constraints). This suggests that nontrivial quantum effects may be needed to describe the onset of hydrodynamic behavior in heavy-ion collisions. Also, we investigate whether there is an upper bound for the initial entropy of the plasma. We find numerical evidence for such a bound in our simulations and show that close to it the system evolves with approximately zero entropy production at early times, even though it is far from equilibrium.