The age problem and growing of structures for open system cosmology

A new equation for the density contrast is derived in the framework of reex amined Newtonian cosmology if we take into account adiabatic matter creatio n in the universe. The age of the universe and the reach of non linear regi me of the density contrast are usually treated separately in the literature and this may lead to controversial conclusions regarding the most adequate scenario to describe the universe. We relate the age of the universe and t he growing mode of the density contrast by introducing a variable that rela tes both of them, so that both aspects are treated simultaneously. We apply this procedure to the Friedmann type model where the source of particle pr oduction is Psi = 3n betaH.