At a turning point, or inflection, where the wave equation changes from an upward moving point through an infinitely short (presumably) change to a downward moving path, the inflection seems to impose the condition that an almost bewildering variety of different paths may begin. The wave, at the inflection, does not know whether it is continuing a sine wave, hyperbola, straight line, circle, ellipse, or any other smooth continuous curve.
I saw a group of the possibilities within a photon wave. It was either an energy or a momentum wave. I used ideas like the Planck Time and Planck Length to get a sense of the wave's image. Anyway, the instant of ambiguity at the inflection seems to be where uncertainty may arise as to frequency, momentum or whatever other variable the wave is following, will do.
At that point, it appears the wave loses a very minute part of it's true nature into the probability that it is one of SEVERAL possibilities a,d the ambiguity results in that minute loss which may be a part of, say, a quantum theory of the observed red shift in light from extremely distant galaxies.
Again, in that instant he possibilities apart from the true path (which eventually of course dominates) includes ellipse, a circular paths in the wrong direction, a hyperbola, gaussian, etc. It helps to become familiar with the Planck action quantum, the Planck mass, Planck time, Planck length and other small constants, because most of the waves we visualize are in light or sometimes radio-tv waves.