Compactification (physics)

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For the concept of compactification in mathematics, see compactification (mathematics)

In physics, compactification plays an important part in string theory.

In string theory, compactification refers to "curling up" the extra dimensions (six in the superstring theory), usually on Calabi-Yau spaces or on orbifolds. The mechanism behind this type of compactification is described by the Kaluza-Klein theory, under the name compact dimension. Models in which the compact directions support fluxes are known as flux compactifications.

The formulation of more precise versions of the meaning of compactification in this context has been promoted by discoveries such as the mysterious duality.

[edit] Flux compactification

A flux compactification is a particular way to deal with additional dimensions required by string theory. It assumes that the shape of the internal manifold is a Calabi-Yau manifold or generalized Calabi-Yau manifold which is equipped with non-zero values of fluxes, i.e. differential forms that generalize the concept of a magnetic field (see p-form electrodynamics).

The hypothetical concept of the anthropic landscape in string theory follows from a large number of possibilities in which the integers that characterize the fluxes can be chosen without violating rules of string theory. The flux compactifications can be described as F-theory vacua or type IIB string theory vacua with or without D-branes.