Kaluza-Klein theory

HomePage | Recent changes | View source | Discuss this page | Page history | Log in |

Printable version | Disclaimers | Privacy policy

Kaluza-Klein theory is a model which unifies classical gravity and electromagnetism. It was discovered by the mathematician Theodor Kaluza that if general relativity is extended to a five-dimensional spacetime, the equations can be separated out into ordinary four-dimensional gravitation plus an extra set, which is equivalent to Maxwell's equations for the electromagnetic field. So, the proposal would go, electromagnetism is a manifestation of curvature in a fourth spatial dimension the same way that gravitation is a manifestation of cuvature in the first three. Klein proposed that the reason this dimension is undetected is that it is curled up with a very small radius, i.e. that a particle moving a short distance along that axis would return to where it began. The distance a particle can travel before reaching its initial position is said to be the size of the dimension. This, in fact, also gives rise to quantization of charge, as waves directed along a finite axis can only occupy discrete frequencies.

Kaluza-Klein theory can be extended to cover the other fundamental forces - namely, the weak and strong forces, but a straightforward approach runs into difficulties involving chirality. Moreover the theory as it stands does not deal with quantum effects. However, the same approach to unification of forces is taken by some more modern theories, notably string theory and the related M-theory.

Further reading:

  1. Hyperspace : A Scientific Odyssey Through Parallel Universes, Time Warps, and the Tenth Dimension - Michio Kaku, Robert O'Keefe

Question: should we really be linking to optical isomerism for chirality here? That article seems to be mostly about chemistry; while the concept might be similar in theoretical physics, it certaintly has different details.

I have created a new page - chirality - and have added chemical meaning but I do not know + could not find physics meaning for it.