Observables and Information

Abstract

The discovery of quantum mechanics was made in 1925, and the statistical interpretation of quantum mechanics which came to be generally accepted was made by Born in 1926. At that time Born pointed out, however, that uncertainty in quantum mechanics had implications that were quite different from those in already existing branches of statistical physics. Since information theory was not developed until 1949, however, the nature of this distinction remained unclear for some time, and has received little attention in much of the subsequent literature. Consequently, various attempts to restore the determinism of Newtonian physics have proliferated; they include the theory of the universal wave function, the theory of hidden variables, and the ‘many worlds’ interpretation of quantum mechanics. In general these theories require the existence of a multiplicity of phenomena that are unobservable; they do not represent information to be gained; and therefore will not receive consideration in the present context. In this chapter we shall give a general account of quantum mechanics in a form which is consistent with quantal information theory and which provides the underlying reasons why such imaginative attempts to model phenomena that are, as far as is known, unpredictable have not been rewarded.