2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/34085The dynamics of our universe is characterised by the density parameters for cosmological constant ($Ω_V$), nonbaryonic darkmatter($Ω_{\rm wimp}$), radiation ($Ω_R$) and baryons ($Ω_B$). To these parameters -- which describe the smooth background universe -- one needs to add at least another dimensionless number ($\sim 10^{-5}$) characterising the strength of primordial fluctuations in the gravitational potential, in order to ensure formation of structures by gravitational instability. I discuss several issues related to the description of the universe in terms of these numbers and argue that we do not yet have a fundamental understanding of these issues.Based on the invited talk at the XIII Rencontres de Blois - Frontiers of the Universe, June 17-23,2001General Relativity and Quantum CosmologyAstrophysicsHigh Energy Physics - Theorytext