Thomas Young
Young, Thomas (1773-1829) was a British physicist, doctor, and scholar. He discovered the interference of light and showed that light consists of waves.
Young was born on June 13, 1773, at Milverton, in Somerset, England, and trained as a doctor in London, Edinburgh, Göttingen, and Cambridge. He was elected a fellow of the Royal Society at the age of 21. In 1801, he became professor of natural philosophy at the Royal Institution, England's scientific society. In 1811, he was elected physician at St. George's Hospital, London, where he remained until his death.
Young determined that the eye focuses by changing the shape of the lens. He was the first to propose that structures in the retina respond to the colors red, green, and violet, and to recognize that color blindness is caused by the inability of some of the structures to respond to light.
From 1800 to 1803, Young published papers, based on his experiments, that revived the theory that light existed in the form of waves. He discovered interference, an effect caused by two waves of the same kind passing through the same space. From about 1815 to 1819, Augustin Fresnel, a French physicist, provided still more evidence. By 1850, the wave theory of light was almost universally accepted, replacing the particle theory of light of English physicist and mathematician Isaac Newton.
Young also discovered how to interpret some of the inscriptions on the Rosetta stone, found in 1799 near Rosetta, Egypt. The stone contains inscriptions in classical Greek, an Egyptian script called demotic, and hieroglyphics. Young translated the demotic text but could not relate the demotic characters to the hieroglyphic pictures. French Egyptologist Jean-Francois Champollion later deciphered the hieroglyphics.
Young died May 10, 1829, in London.