Christian Huygens, a contemporary of Newton's, thought light was a wave and proposed a theory or principle that is still useful in understanding the propagation of waves.
Huygens' Principle is that every point on a wavefront is the source of new wavelets and the new wavefront is the envelope of these wavelets.
As a wave encounters an obstruction &emdash; like a slit edge &emdash; the new wave bends around this obstruction.
(c) Doug Davis, 2002; all rights reserved
Return to Ch 20, Wave Optics: Interference and Diffraction