ABSTRACT
The amplitudes of the waves of quantum wave mechanics were framed in complex numbers, but their "squares" were real numbers representing a directly interpretable physical quantity. Quantum mechanics allows an electron to have only one of two values of spin along any chosen axis. The Stem-Gerlach apparatus can separate a beam of electrons into two beams, all of those in a given output beam having the same spin value. The great physicist Niels Bohr attempted to frame an overall picture of the world that would do justice to the strange new quantum phenomena and to design the appropriate theoretical structure. The basic formalism of quantum theory is clear, and its application to the world of observation and experiment is, in practice, no more controversial than that of any other formal physical theory. S. Kochen's interpretation rests upon an important theorem of quantum mechanics.
