Quantum mechanics is derived as an application of the method of maximum
entropy. No appeal is made to any underlying classical action principle whether
deterministic or stochastic. Instead, the basic assumption is that in addition
to the particles of interest x there exist extra variables y whose entropy S(x)
depends on x. The Schr\"odinger equation follows from their coupled dynamics:
the entropy S(x) drives the dynamics of the particles x while they in their
turn determine the evolution of S(x). In this "entropic dynamics" time is
introduced as a device to keep track of change. A welcome feature of such an
entropic time is that it naturally incorporates an arrow of time. Both the
magnitude and the phase of the wave function are given statistical
interpretations: the magnitude gives the distribution of x in agreement with
the usual Born rule and the phase carries information about the entropy S(x) of
the extra variables. Extending the model to include external electromagnetic
fields yields further insight into the nature of the quantum phase.Comment: 29 page
