A Kaluza–Klein Approach to Double and Exceptional Field Theory

We examine the challenge of viewing all the fields in supergravity as arising from a Kaluza–Klein like dimensional reduction of some higher‐dimensional theory. This gives rise to what is known as exceptional field theory or double field theory. A particular emphasis is placed on following the Kaluza–Klein intuition leading to the identification of charged states and a reinterpretation of the central charges. We further give a description of the novel extended geometry as a generalised phase space and the relationship to string and M‐theory theory and the notion of quantization.