2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/202162In his search for a unified field theory that could undercut quantum mechanics, Einstein considered five dimensional classical Kaluza-Klein theory. He studied this theory most intensively during the years 1938-1943. One of his primary objectives was finding a non-singular particle solution. In the full theory this search got frustrated and in the x^5-independent theory Einstein, together with Pauli, argued it would be impossible to find these structures.25 pages, 2 figures, To appear in Stud. Hist. Phil. Mod. PhysGeneral Relativity and Quantum CosmologyHigh Energy Physics - PhenomenologyHigh Energy Physics - TheoryHistory and Philosophy of Physicstext