2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/148240In these lectures I discuss various unsolved problems of string theory and their relations to quantum gravity, 3d Ising model, large N QCD, and quantum cosmology. No solutions are presented but some new and perhaps useful approaches are suggested.18 pages, latex (references added)High Energy Physics - Theorytext