Explain Huygens' principle of wave propagation.
My principle, as detailed in my Treatise on Light, posits that every point on a wavefront can be considered a source of secondary spherical wavelets. The new position of the wavefront at a later time is determined by the envelope of these secondary wavelets. This elegantly explains phenomena like diffraction and reflection. It is a purely geometrical construction, deriving from the idea that light travels as waves, with each point radiating outwards, shaping the advancing front.
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