Thomas Young (scientist)

Thomas Young was a British polymath who made massive contributions to many different sciences. A polymath is a person who excels in many different fields of study. Young's expertise spanned vision, light, solid mechanics, energy, physiology, language, musical harmony, and Egyptology. Born in 1773 in Milverton, Somerset, he was the eldest of ten children. By age 14, he had mastered eleven different languages. These included Greek, Latin, French, Italian, Syriac, Samaritan Hebrew, Arabic, Biblical Aramaic, Persian, Turkish, and Ge'ez.

One of Young's most significant achievements was establishing the wave theory of light. For over a century, many scientists followed Isaac Newton's corpuscular theory. This theory suggested that light was made of tiny particles. Young argued instead that light behaves like a wave, a view originally proposed by Christiaan Huygens. To prove this, he used experiments involving interference. He used a ripple tank to show how water waves interact. He also performed experiments with light, including a version of the double-slit experiment. In 1804, he described using a card in a beam of light from a window. He observed colorful fringes in the shadows and at the sides of the card. When he blocked parts of the light beam, these fringes disappeared. This provided strong evidence that light moves in waves.

Young also transformed our understanding of how the human eye works. He is often called the founder of physiological optics. In 1793, he explained how the eye accommodates itself to see at different distances. He discovered this happens through changes in the curvature of the crystalline lens. In 1801, he was the first person to describe astigmatism. He also proposed the Young–Helmholtz theory regarding color perception. He suggested that the retina contains three kinds of nerve fibers. This idea predicted that the eye has three color receptors sensitive to different wavelengths. This work laid the foundation for modern color vision science.

In the field of engineering, Young introduced a vital concept called Young's modulus. This is denoted by the letter E. It describes the elasticity of a material. Specifically, it relates stress to strain. Stress is the compression or decompression applied to a body. Strain is the fractional change in the length of that body. Before this, engineers used Hooke's law, which relied on a constant called k. However, k changed depending on the shape and size of an object. Young's modulus is an intensive property. This means it depends only on the material itself, not its geometry. This discovery allowed engineers to predict how a component would react to stress. It revolutionized how structures are designed and built.

Young's scientific career was filled with many official roles and responsibilities. He studied medicine at St Bartholomew's Hospital and the University of Edinburgh. He later earned his medical degree from the University of Göttingen in 1796. In 1801, he became a professor of natural philosophy at the Royal Institution. He delivered 91 lectures in just two years. He also served as the foreign secretary of the Royal Society starting in 1802. In 1818, he became the secretary to the Board of Longitude. He also served as the superintendent of the HM Nautical Almanac Office. Even while doing science, he maintained a practice as a physician in London.

Beyond physics and medicine, Young was a key figure in deciphering ancient history. He was instrumental in the decipherment of Egyptian hieroglyphs. He specifically worked with the Rosetta Stone to unlock these ancient writings. His linguistic skills allowed him to bridge the gap between modern science and ancient culture. He was also interested in capillary phenomena and surface tension. In 1804, he developed a theory regarding how liquids move through small spaces. This work was later unified by Carl Friedrich Gauss into the Young–Laplace equation. This formula describes the pressure difference across the interface of two static fluids.

Despite his brilliance, Young faced some challenges in communicating his ideas. He had a reputation for being difficult to understand. A contemporary named George Peacock noted that Young's words were not in familiar use. He said the arrangement of Young's ideas was often different from how others spoke. Even the Lords of the Admiralty found his papers on elasticity too learned to understand. Young died in London in 1829 at the age of 56. His autopsy showed he had atherosclerosis of the aorta. His work, however, left a lasting legacy. He influenced many great scientists, including James Clerk Maxwell and Albert Einstein.