Kaluza-Klein Theory in Perspective

TL;DR

This paper reviews the modern perspective on Kaluza-Klein theory, emphasizing its role in unification and superstring theory, and introduces the novel interpretation of string states as black holes.

Contribution

It provides a contemporary overview of internal dimensions in physics and presents a new interpretation of Kaluza-Klein string states as extreme black holes.

Findings

Kaluza-Klein dimensions are integral to unification theories.

Superstring theory incorporates internal dimensions.

Kaluza-Klein string states can be viewed as extreme black holes.

Abstract

The Kaluza-Klein idea of extra spacetime dimensions continues to pervade current attempts to unify the fundamental forces, but in ways somewhat different from that originally envisaged. We present a modern perspective on the role of internal dimensions in physics, focussing in particular on superstring theory. A novel result is the interpretation of Kaluza-Klein string states as extreme black holes.(Talk delivered at the Oskar Klein Centenary Nobel Symposium, Stockholm, September 19-21, 1994.)