We assume that light travels past a boundary in straight lines, casting a hard shadow.
	Huygen's principle predicts the light will bend around the obstacle and cast a soft-edged shadow. This is what occurs in reality.
	As wavelength increases, the light bends further around the edge into the shadow region increasing the softness of the shadow's edge.
	Light, traveling through an aperture spreads out in in all directions, creating a diffraction spot. Instead of a hard edged patch of light a larger soft-edged patch is observed.
	As wavelength increases, the soft edged patch grows.
	A 3D representation of light traveling through an aperture. The light spreads in all directions. The flat spokes indicate the arrival times are always out of phase (see here for another example). (320X240) (640 X 480)
	A different 3D representation of light traveling through an aperture. (320X240) (640 X 480)

Characteristics of Light | Illustration of light as a ray | Illustrating Huygen's Principle | The actions and effects of lenses | Holography | Eyes | Simple optical systems