2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/11800It is shown that density fluctuations obey a scaling law in an open Friedmann universe. In a flat universe, the fluctuations are not scale-invariant. We compute the growth rate of adiabatic scale-invariant density fluctuations in flat, open and inflationary universes. We find that, given a sufficiently long time, the density perturbations decay away in the Einstein-de-Sitter universe. On the contrary, the rapid growth of the density instabilities makes an open universe inhomogeneous in a time scale comparable to the age of our universe. We also find that the fluctuations grow exponentially in a flat inflationary universe.latex file, 19 pagesAstrophysicsGeneral Relativity and Quantum CosmologyHigh Energy Physics - Theorytext