
Abstract 
1 
Introduction 

1.1 
Preface 

1.2 
Introduction to
part I 
2 
The Possibilities of Generalizing General Relativity: A Brief
Overview 

2.1 
Geometry 

2.2 
Dynamics 

2.3 
Number field 

2.4 
Dimension 
3 
Early
Attempts at a Unified Field Theory 

3.1 
First steps in the development of unified
field theories 

3.2 
Early disagreement about how to explain elementary particles
by field theory 
4 
The Main Ideas for Unification between about 1918 and
1923 

4.1 
Weyl’s theory 

4.2 
Kaluza’s fivedimensional unification 

4.3 
Eddington’s
affine theory 
5 
Differential Geometry’s High Tide 
6 
The Pursuit of Unified
Field Theory by Einstein and His Collaborators 

6.1 
Affine and mixed
geometry 

6.2 
Further work on (metric) affine and mixed geometry 

6.3 
Kaluza’s
idea taken up again 

6.4 
Distant parallelism 
7 
Geometrization of the Electron
Field as an Additional Element of Unified Field Theory 

7.1 
Unification of
Maxwell’s and Dirac’s equations, of electrons and light 

7.2 
Dirac’s electron
with spin, Einstein’s teleparallelism, and Kaluza’s fifth dimension 

7.3 
Einstein,
spinors, and semivectors 
8 
Less Than Unification 
9 
Mutual Influences
Among Mathematicians and Physicists? 
10 
Public Reception of Unified
Field Theory at the Time 
11 
Conclusion 
12 
Acknowledgements 

References 

Footnotes 

Biographies 