ABSTRACT
In this chapter, the authors show that various pictures of quantum mechanics are interrelated by the unitary transformations. Calling upon the correspondence principle, the quantum-mechanical scattering problem would be quite analogous to the mentioned classical model. The two analysed pictures of quantum mechanics are not the only possible ones. Quite the opposite, all the unitary transformations carried out on the state vectors and the observables of the Schrödinger picture, in fact, define a new formalism of quantum mechanics. There are infinitely many such formalisms but they are all rigorously equivalent. Among all of the possible, alternative pictures of quantum mechanics, of particular importance for scattering theory is the so-called interaction picture, which was first introduced by Dirac. Hence, the alternative name: the Dirac picture.
