Complex sentence: From 1918 until 1923, there were three distinct approaches to field theory: the gauge theory of Weyl, Kaluza's five-dimensional theory and Eddington's development of affine geometry.
Split into simpler sentences: From 1918 until 1923, there were three distinct approaches to field theory. The gauge theory of Weyl, Kaluza's five-dimensional theory and Eddington's development of affine geometry.