Einstein and the Kaluza-Klein particle
Abstract In 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.