We consider deterministic, time-reversible dynamics with random initial data, in a low-density scaling. Under suitable assumptions on the initial measure, a strong chaos prop- erty is propagated in time, which also encodes the transition to irreversibility. This result is complemented by a theory of fluctuations, allowing to establish the connection between microscopic and hydrodynamic scales, at least for perturbations of a global equilibrium. Many of the open problems left require a deeper understanding of the coupling mechanisms between deterministic and stochastic dynamics