2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/7154Atomic and molecular transitions for high Z objects in the early universe give bounds to the possible existence of extra spatial dimensions $D = 3+ε$. We review the theory and present observational data, based on Lyman and Balmer hydrogen transitions of distant quasars and CO rotational transitions of far away giant molecular clouds.15 pages. To appear in the book "Recent Research Developments in Astonomy and Astrophysics" (Research Signpost, India)Astrophysicstext