2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/35807This paper is a sequel of the series of papers [gr-qc/9409010, gr-qc/9505034, gr-qc/9603022], being an immediate continuation and development of the latter of them. In the Friedmann universe, the equation $Ω_0=2q_0$ holds ($Ω$ is density parameter, $q$ is deceleration parameter, and subscript 0 indicates present-day values), which gives rise to the problem of the missing matter as observational data give $Ω_0<2q_0$. In the cosmic-length universe, $Ω_0=2q_0- L/R_0^3H_0^2$ ($R_0$ is the radius of the universe, $H_0$ is Hubble constant), which lifts the problem. The cosmic length, $L=const \approx 1/H_0$, is the infimum of the set of maximal radii of a closed universe.7 pages, LATEX 2.09General Relativity and Quantum CosmologyAstrophysicstext