Fundamental interactions and quantum behaviour in unified field theory

Abstract: The concept of unified field theory is discussed. Two nonlinear field models with world volume type action are considered, namely extremal space-time film model and Born -- Infeld nonlinear electrodynamics. The natural appearance of two long-range fundamental interactions, electromagnetism and gravitation, in these field models is discussed. The quantum behaviour of the interacting solitons-particles is considered. The concept of quasi-bounding quantization in nonlinear field models is introduced.