Via holographic duality (or ‘AdS/CFT'), the process of black hole formation and evaporation corresponds to the process of thermalization of certain (unitary) quantum field theories, evolving from non-equilibrium initial states towards thermal equilibrium. In this context, the question of how thermal a generic high-energy eigenstate looks in a theory with a holographic dual is closely tied to the question of how legitimately one may consider the dual geometry of this pure state to be a black hole. In this thesis we present some results which shed light on the nature of this relationship, through a detailed study of the dynamics of the so-called SYK model —a holographic, many-body quantum mechanical system of interacting fermions. The results indicate that this model satisfies the eigenstate thermalization hypothesis, which we extend to explore its implications on certain quantum chaotic properties the SYK Hamiltonian that mirror the quantum chaotic behavior of black holes.