ABSTRACT
THE laws of measurement in atomic physics, developed in the preceding chapter, are dominated by the fact that, in general, every microphysical observation produces an unknown and non-negligible change in some of the characteristics of the system observed. Thus a measurement of the values of a variable y may produce changes in the values of another variable z,
The present chapter expresses this principle in a precise, quantitative form by means of Heisenberg's exchange relations (Vertauschungsrelationen), and applies these relations to develop the theory of the angular momentum operators, and to obtain the equations of motion in quantum mechanics.
