2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/205834It is the common consensus that the expansion of a universe always slows down if the gravity provided by the energy sources therein is attractive and accordingly one needs to invoke dark energy as a source of anti-gravity for understanding the cosmic acceleration. To examine this point we find counter-examples for a spherically symmetric dust fluid described by the Lemaitre-Tolman-Bondi solution without singularity. Thus, the validity of this naive consensus is indeed doubtful and the effects of inhomogeneities should be restudied. These counter-intuitive examples open a new perspective on the understanding of the evolution of our universe.41 pages, 12 figures, 4 tables; final version for publicationAstrophysicsGeneral Relativity and Quantum Cosmologytext