Classical model S_dc of Dirac particle S_D is constructed. S_D is the dynamic system described by the Dirac equation. Its classical analog S_dc is described by a system of ordinary differential equations, containing the quantum constant h as a parameter. Dynamic equations for S_dc are determined by the Dirac equation uniquely. Both dynamic systems S_D and S_dc appear to be nonrelativistic. One succeeded in transforming nonrelativistic dynamic system S_dc into relativistic one S_dcr. The dynamic system S_dcr appears to be a two-particle structure (special case of a relativistic rotator). It explains freely such properties of S_D as spin and magnetic moment, which are strange for pointlike structure. The rigidity function f_r(a), describing rotational part of total mass as a function of the radius
a of rotator, has been calculated for S_dcr. For investigation of S_D and construction of S_dc one uses new dynamic methods: dynamic quantization and dynamic disquantization. These relativistic pure dynamic procedures do not use principles of quantum mechanics (QM). They generalize and replace conventional quantization and transition to classical approximation. Totality of these methods forms the model conception of quantum phenomena (MCQP). Technique of MCQP is more subtle and effective, than conventional methods of QM. MCQP relates to conventional QM, much as the statistical physics relates to thermodynamics.
Classical model S_{Dcl} of the Dirac particle S_D is constructed. S_D is the dynamic system described by the Dirac equation. For investigation of S_D and construction of S_{Dcl} one uses a new dynamic method: dynamic disquantization. This relativistic purely dynamic procedure does not use principles of quantum mechanics. The obtained classical analog S_{Dcl} is described by a system of ordinary differential equations, containing the quantum constant
ℏ as a parameter. Dynamic equations for S_{Dcl} are determined by the Dirac equation uniquely. The dynamic system S_{Dcl} has ten degrees of freedom and cannot be a pointlike particle, because it has an internal structure. There are two ways of interpretation of the dynamic system S_{Dcl}: (1) dynamical interpretation and (2) geometrical interpretation. In the dynamical interpretation the classical Dirac particle S_{Dcl} is a two-particle structure (special case of a relativistic rotator). It explains freely such properties of S_D as spin and magnetic moment, which are strange for pointlike structure. In the geometrical interpretation the world tube of S_{Dcl} is a ''two-dimensional broken band'', consisting of similar segments. These segments are parallelograms (or triangles), but not the straight line segments as in the case of a structureless particle. Geometrical interpretation of the classical Dirac particle S_{Dcl} generates a new approach to the elementary particle theory.
The Dirac particle S_D is investigated by means of dynamic methods, i.e. without a use of the principles of quantum mechanics. It is shown that the Pauli particle S_P and the nonrelativistic approximation S_{nD} of the Dirac particle S_D are different dynamic systems. S_{nD} contains the high frequency degrees of freedom, which are absent in the dynamic system S_P. It means that the nonrelativistic Dirac particle S_{nD} is composite (i.e. it has internal degrees of freedom), whereas the Pauli particle S_P is a pointlike particle with the spin. In the absence of the electromagnetic field the world line of the classical Pauli particle S_{Pcl} is a timelike straight, whereas that of the classical nonrelativistic Dirac particle S_{nDcl} is a helix. The characteristic frequency $Ω=2mc^{2}/\hbar $ of this helix is the threshold frequency of the pair production. Using dynamic methods, one shows freely that the Copenhagen interpretation, when the wave function is a specific quantum object describing the state of individual particle, is incompatible with the quantum mechanics formalism. Besides, it is shown that the momentum distribution in quantum mechanics is in reality the mean momentum distribution. Effectiveness of different investigation strategies is discussed and compared.
The purpose of this chapter is to introduce the Dirac equation, which will provide us with a basis for developing the relativistic quantum mechanics of electronic systems. Thus far we have reviewed some basic features of the classical relativistic theory, which is the foundation of relativistic quantum theory. As in the nonrelativistic case, quantum mechanical equations may be obtained from the classical relativistic particle equations by use of the correspondence principle, where we replace classical variables by operators. Of particular interest are the substitutions In terms of the momentum four-vector introduced earlier, this yields In going from a classical relativistic description to relativistic quantum mechanics, we require that the equations obtained are invariant under Lorentz transformations. Other basic requirements, such as gauge invariance, must also apply to the equations of relativistic quantum mechanics. We start this chapter by reexamining the quantization of the nonrelativistic Hamiltonian and draw out some features that will be useful in the quantization of the relativistic Hamiltonian. We then turn to the Dirac equation and sketch its derivation. We discuss some properties of the equation and its solutions, and show how going to the nonrelativistic limit reduces it to a Schrödinger-type equation containing spin.
Quantum systems are dynamic systems restricted by the principles of quantum mechanics (linearity of dynamic equations, linear transformation of the wave function etc.). One suggests to investigate the quantum systems simply as dynamic systems, ignoring the quantum principles and constraints imposed by them. Such dynamic methods of investigation appear to be more adequate and effective, than the conventional quantum methods of investigation. Using these methods, which ignore the quantum principles, one can overcome the principal problem of quantum field theory: join of nonrelativistic quantum principles with the relativity principles. Investigation of dynamic system, described by the Schroedinger equation, admits one to prove that the Copenhagen interpretation is incompatible with quantum mechanics formalism. Besides, it is shown that sometimes the application of quantum principles leads to incorrect results.
The distributed system
SD described by the Dirac equation is investigated simply as a dynamic system, i.e. without usage of quantum principles. The Dirac equation is described in terms of hydrodynamic variables: 4-flux
ji, pseudo-vector of the spin
Si, an action
ℏϕ and a pseudo-scalar
κ. In the quasi-uniform approximation, when all transversal derivatives (orthogonal to the flux vector
ji) are small, the system
SD turns to a statistical ensemble of classical concentrated systems
Sdc. Under some conditions the classical system
Sdc describes a classical pointlike particle moving in a given electromagnetic field. In general, the world line of the particle is a helix, even if the electromagnetic field is absent. Both dynamic systems
SD and
Sdc appear to be non-relativistic in the sense that the dynamic equations written in terms of hydrodynamic variables are not relativistically covariant with respect to them, although all dynamic variables are tensors or pseudo-tensors. They becomes relativistically covariant only after addition of a constant unit timelike vector
fi which should be considered as a dynamic variable describing a space-time property. This "constant" variable arises instead of
γ-matrices which are removed by means of zero divizors in the course of the transformation to hydrodynamic variables. It is possible to separate out dynamic variables
κ,
κi responsible for quantum effects. It means that, setting
κ,κi≡0, the dynamic system
SD described by the Dirac equation turns to a statistical ensemble
EDqu of classical dynamic systems
Sdc.