Measurement and Quantum Silence

Abstract

The central problem in the interpretation of the quantum theory is how to understand the superposition of the eigenstates of an observable. To a considerable extent scientific practice here, especially as codified in versions of Bohr’s Copenhagen interpretation, follows an interpretive principle that I have elsewhere called the Rule of Silence (Fine 1987). That rule admonishes us not to talk about the values of an observable unless the state of the system is an eigenstate, or a mixture of eigenstates, of the observable in question. With regard to the Rule of Silence, as in other matters bearing on the interpretation of the quantum theory, Einstein was one of the first to realize that there can be difficulties. They appear as soon as we look at something like an explosion; i.e., the interaction between a micro- and a macrosystem that involves the amplification of a microphenomenon to macroscopic scale (Fine 1988 Chap. 5, esp. p. 78ff.). John Bell describes the difficulty over the Rule of Silence this way.

Nowadays, we have stripped Maxwell of his phi- losophy and retained only his equations. Perhaps we should do a similar job on quantum mechanics.

(H.R. Post 1974, p. 14.).