2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/51154We discuss the problem of introducing background spacetimes of the de Sitter type (quintessential backgrounds) in the context of fundamental theories involving supersymmetry. The role of a model presented in 1984, showing that these backgrounds can occur as spontaneously broken phases of locally supersymmetric 4D, N-extended theories, is highlighted. The present twin challenges of the presumed presence of supersymmetry in particle physics and the emergence of experimental evidence for a positive cosmological constant from type-II supernovae data are noted for the continued investigation of superstring/M-theory. Finally we note how the 1984-model may have a role to play in future investigations.Extended version of presentation at the SG@25 conference, SUNY@Stony Brook, Dec. 1-2, 2001, 35pp., 1 fig., LaTeX twiceHigh Energy Physics - Theorytext