1 2 Ju l 2 00 5 Dynamical methods of investigation in application to the Dirac particle

The Dirac particle SD 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 SP and the nonrelativistic approximation SnD of the Dirac particle SD are different dynamic systems. SnD contains the high frequency degrees of freedom, which are absent in the dynamic system SP. It means that the nonrelativistic Dirac particle SnD is composite (i.e. it has internal degrees of freedom), whereas the Pauli particle SP is a pointlike particle with the spin. In the absence of the electromagnetic field the world line of the classical Pauli particle SPcl is a timelike straight, whereas that of the classical nonrelativistic Dirac particle SnDcl is a helix. The characteristic frequency Ω = 2mc2/h̄ 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.