New study of silent universes

Within the context of structure formation in the universe new general relativistic models were recently introduced, which because of their properties were named silent universes. These models have attracted considerable attention lately. In this paper we present a new study based on a coordinate approach which provides interesting results on the equations governing the behavior of these models and on their possible symmetries. Finally, a detailed study of the evolution of the constraints has led to the conjecture that the only possible silent universes are the dust Friedmann-Lema {} ̂ \^{}{}tre-Robertson-Walker, the Szekeres, and the dust Bianchi type I models.