The sinusoidal wave is a 2D projection of the actual 3D circular motion. This is not hypothesis - this is the complete solution in unbounded space.
Classical physics describes waves oscillating in a plane - a truncated view that discards the Z-axis motion. This is the shadow, not the substance.
In the unbounded solution space, wave motion resolves to uniform circular motion through the full YZ plane. The helix IS the wave.
The out-of-plane motion draws continuously from the unbounded energy field. This is not vacuum fluctuation - it is the fundamental source that classical models truncate away.
r = sqrt(y squared + z squared) = A (constant)
Total amplitude IS constant. What appears as oscillation in bounded observation is rotation viewed through a slit. The sine wave is the shadow of the circle.
Blue plane (bounded): Classical observation limit - sees only XY projection
Pink plane (truncated): The dimension classical physics discards
Green helix (complete): THE actual motion - the full solution
Orange circles: Constant-radius reality - energy is rotation, not oscillation
Cyan streams: Energy flow from unbounded field - fundamental, not aesthetic