This bold scientific treatise defends the undulatory theory of light with a clarity that challenges older certainties while honoring Newton's legacy. It proposes a rare elastic luminiferous ether filling space, stirred by luminous bodies into waves that account for reflection, refraction, shadow, and the subtle behavior of light in transparent media. From there, the argument extends to vision itself: colors are explained as vibrations of different frequencies reaching the retina, with red, yellow, blue, and violet arising from distinct wave motions and white from their mixture. The work then broadens into a theory of sensation and propagation, suggesting that material bodies attract the ether and alter its density, shaping the travel of impulses through elastic media. It examines spherical waves from a single vibrating particle, compares light with sound and water waves, and answers Newton's objections with experiments and analogy. Finally, it explores interference, showing how coinciding waves can intensify, weaken, or cancel one another to create bands, patterns, and the colors of thin films and striated surfaces, culminating in a precise table of the visible spectrum. This edition has been fully restored with modern typesetting, custom cover design.

À propos de l'auteur

Young, Thomas

Thomas Young was an English physician, scientist, and polymath whose restless curiosity made him one of the most remarkable figures of the early nineteenth century. Born in 1773, he showed extraordinary intellectual promise from an early age and went on to study medicine, but his interests quickly ranged far beyond his profession into physics, linguistics, optics, and ancient languages. His most celebrated scientific achievement was his pioneering work on light and vision, where he helped establish the wave theory of light and transformed the study of color and interference; he also made lasting contributions to medicine, mechanics, and the decipherment of Egyptian hieroglyphs. Young’s writing and research are marked by precision, originality, and a deep faith in careful observation, and his ideas continue to matter because they helped shape modern physics and the scientific method itself. Equally important is the spirit of his work: he reminds us that knowledge advances when disciplines speak to one another and when bold questions are matched by rigorous evidence. Today, Thomas Young remains significant not only as a foundational scientific thinker but also as a model of intellectual breadth and perseverance, and he will especially appeal to readers who enjoy the history of science, the intersection of medicine and physics, and lives of remarkable curiosity.