Purturbation

Full Title

for discrete?

from Born

What we shall do, is to bring the classical laws for the perturbation of a mechanical system, caused by internal couplings or external fields, into one and the same form, which would very strongly suggest the formal passage from classical mechanics to a 'quantum mechanics'. For this, the quantum rules as such will be retained essentially unchanged; as multiples of the action quantum h there will appear the action integrals of the unperturbed system, 4) which is assumed to be separable and non-degenerate. On the other hand, mechanics itself will undergo a change, in the sense of a transition from differential to difference equations, as already exhibited by Bohr's frequency conditions. In the simple case of non-degenerate systems, there seems then to be no room left for arbitrariness.