Instructions:
Click to add a new source.
Explanation:
Now known as the Huygens-Fresnel Principle, this interpretation of light posits that wavefronts are just the sum of many spherical wavelets. This was proposed in in 1678 by Christiaan Huygens and refined by Augustin-Jean Fresnel a century or so later. This simulation takes as inspiration a figure from Huygens' Treatise on Light.
Link to stand-alone sim: Here is a link to view the sim on its own, with no distractions.