2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/11369We discuss the implications of two possible, recent Sunyaev-Zel'dovich (SZ) detections for which no optical or X--ray counterparts have been found. This suggests that the objects reside at high redshift, which is difficult to reconcile with a critical cosmology. We develop this argument and find that an open model with $\Omo=0.2$ remains consistent with what we currently know about the two objects. The reasoning also demonstrates the utility of SZ cluster searches.Proceedings of the PPEUC conference held in Cambridge, UK, April 7-11, 1997Astrophysicstext