Notes on Special Relativity and Quantum Fields
Quantum field theory (QFT) is a theory of relativistic fields for describing the properties of elementary particles and their interaction. Quantum fields enable to describe such physical phenomena as creation and annihilation of elementary particles, and their transformation in each other. The relativistic field is, in fact, a typical example of a continuum system. However, it can be described by a discrete mechanical system with infinite many degrees of freedom, so called field oscillators. This enables one to quantize the classical fields by associativing to the field some discrete quanta of energy, which corresponds to different energetic states of the field oscillators. The elementary particles have some specific spins, internal angular momentum, electric charge and other characteristics. They are identified with the quanta of corresponding relativistic fields. The kinematic properties of elementary particles are described by quantum theory of free (noninteracting) fields. The quantum theory of interacting fields is the theory of the interaction of elementary particles. The QFT is a quantum relativistic theory. It contains two fundamental physical constants, reflecting these properties: the speed of light c and the Plank constant ~. The more ambitious quantum gravity is a further generalization (not completed yet) and contains in addition the Newton gravitational constant G. The relations between different theories can be illustrated on the following diagram