The author considers basic definitions of temporal functions in the quantum field theory (delays in scattering processes and durations of formation of particles and states, their "dressing") and further on their basis experimentally checkable theories are examined: the theory of optical dispersion, the theory of multiphoton processes, the theory of condensed states and phase transitions of the first kind, the theory of near field. The offered approach allows resolving such known difficulties, as the defining of physical sense of some renormalisation procedures, the so-called "superluminal" phenomena, some other paradoxes.