Cosmology and brane worlds: A review.

*(English)*Zbl 1033.83027Fundamental physical theories such as string theory often predict the existence of additional spacetime dimensions higher than four. Whereas it had been believed for a long time that these additional dimensions must be compact and small in size, recent developments have shown that this does not have to be necessarily true: one can have both large and non-compact higher dimensions, without being in conflict with current experiments. A key concept in this respect is the ‘brane world’ scenario according to which our observed universe is a four-dimensional brane embedded into higher dimensions called the ‘bulk’. The bulk can be quite large, since it is assumed that only the gravitational interaction can spread over all dimensions, whereas other interactions are confined to the brane. This paper gives a concise review of the central ideas and recent developments. It focuses in particular on cosmological aspects. The treatment is mostly limited to the case where the bulk is five-dimensional and taken either to be anti-de Sitter space or a solution of the Einstein equations with a scalar field.

Reviewer: Claus Kiefer (Köln)

##### MSC:

83E30 | String and superstring theories in gravitational theory |

83-02 | Research exposition (monographs, survey articles) pertaining to relativity and gravitational theory |

83F05 | Cosmology |

83E15 | Kaluza-Klein and other higher-dimensional theories |