Introduction to the History of Light & Physics Greek Philosophers: Hero: "Hero's Law" Reflection at New World Encyclopedia Hero ("Heron") of Alexandria at Kotaku   Ptolemy: This is the experiment known to Ptolemy, only his lacked a motor to spin the colorwheel, so his disc therefore turned gray. Time-Life Books This example of "additive synthesis" demonstrates the eye's inability to "keep up" with rapid movement, "blending" the colors together. Additive Color Synthesis at bway.net Ptolemy at University of Oregon   During the Middle Ages, succession to the Arab world the study of light: Alhazen (Ibn al-Haytham) & his theory of projected "points of vision" correctly surmises the concept of optical focus. Alhazen at University of Oxford   Johannes Kepler - Preeminence of his optical - retinal theory: Kepler's basic understanding eliminated much confusion Theories of Vision at University of Florida Kepler at NASA.gov and at University of St. Andrews Activity of other Baroque era Scientists:           Cow's eye dissection, after Descartes   Descartes' famous dissection of the eye of an ox René Descartes at The Internet Encyclopedia of Philosophy "Dioptrique" by Descartes at Wikipedia     Newton's experiments with prisms Newton's Prism Experiments at Florida State University Newton and the Color Spectrum at Web Exhibits Newton's Theory of Light at The Star Garden   Snell's experiments with Refraction: Snell's Law of Refraction Snell Willebrord van Royen Snell at University of St. Andrews Snell's Law of Refraction at The Physics Classroom     1802 - Tri-chromatic theory of retinal vision by Thomas Young. The Eye has three types of color receptors, or cones; Red, Green, Blue Tri-Color Vision at Harvard University The Young–Helmholtz Theory at Wikipedia Thomas Young and the Wave Nature of Light at Open Mind       At the early 19th century, general confusion regarding the physical nature of light, due to it's contradictory wavelike & particle-like nature, persisted in educated circles. Antiquated Aristotelian concepts are presented in Goethe's 1810 Theory of Colors, although his observations with regard to color relationships were a predecessor to the psychology of color. Goethe's Color Wheel Goethe on the Psychology of Color and Emotion at Brain Pickings Goethe’s "Theory of Colors": The Treatise That Inspired Kandinsky at Open Culture       Light possesses both particle-like & wave-like properties Wave-Particle Duality at Georgia State University and Boston University     1865 - Hermann von Helmholz elaborated on Young's theory with the introduction of the "overlapping color sensitivity" of the light receptors - now the Young-Helmholz Theory of retinal vision. Von Helmholz at Stanford University The Ophthalmoscope in the Lifetime of Hermann von Helmholtz - Journal of the American Medical Association   General discussion of the Retina and Vision: Rods & Cones at the Rochester Institute of Technology The Photoelectric Effect at Arizona State University home back next lecture contents top