Kitcher's Explanatory Unification, Kaluza–Klein Theories, and the Normative Aspect of Higher Dimensional Unification in Physics

Abstract

I examine the relation between explanation and unification in both the original Kaluza–Klein theory, which originated in the works of Theodor Kaluza and Oskar Klein in the 1920s, and in the modern Kaluza–Klein theories which date back to the late 1970s and which are still considered by the majority of the physics community to be the best hope for a complete unified theory of all fundamental interactions. I use the conclusions of this case study to assess the merits of Philip Kitcher's account of explanation as unification. I also draw lessons about physicists’ pursuit of the higher dimensional unification of the fundamental forces of nature. 1 Introduction 2 Kitcher on Explanatory Unification 3 A Close Look at the Kaluza–Klein Theory 3.1 Kaluza's theory: unification of gravity and electromagnetism 3.2 Klein's theory: an elucidation and elaboration of Kaluza's theory 3.3 Klein's compactification of the fifth dimension: explaining the unobserved 4 A General Overview of the Emergence of the Modern Kaluza–Klein Theories 5 Kaluza–Klein Unification Examined by Kitcher's Standard of Unification 6 Concluding Remarks