5 - Subject and object

Summary

The subject–object distinction is indeed at the very root of the unease that many people still feel in connection with quantum mechanics. Some such distinction is dictated by the postulates of the theory, but exactly where or when to make it is not prescribed. Thus in the classic treatise of Dirac we learn the fundamental propositions:

… any result of a measurement of a real dynamical variable is one of its eigenvalues …,

… if the measurement of the observable ξ for the system in the state corresponding to |x〈 is made a large number of times, the average of all the results obtained will be 〈x|ξ|x〉 …,

… a measurement always causes the system to jump into an eigenstate of the dynamical variable that is being measured ….

So the theory is fundamentally about the results of ‘measurements’, and therefore presupposes in addition to the ‘system’ (or object) a ‘measurer’ (or subject). Now must this subject include a person? Or was there already some such subject–object distinction before the appearance of life in the universe? Were some of the natural processes then occurring, or occurring now in distant places, to be identified as ‘measurements’ and subjected to jumps rather than to the Schrödinger equation? Is ‘measurement’ something that occurs all at once? Are the jumps instantaneous? And so on.