Flow

In 1792, Young began to study medicine in London. He later moved to Gottingen, where he obtained his doctorate in physics in 1796. A year later, in 1797, Young entered Emmanuel College at Cambridge. By 1799, Young had established himself as a physician in London where he published many of his first academic articles anonymously to protect his reputation at a physician. It is to be noted that while studying medicine in London, he explained the mode by which the eye accommodates itself to vision at different distances as depending on change of the curvature of the crystalline lens. This was to prove valuable to him being the first to describe astigmatism.

In 1801, Thomas Young was appointed professor of natural philosophy (mainly physics) at the Royal Institution in Cambridge. His initial interest in light and vision carried over to this new academic endeavor. Here, Young presented the hypothesis, later developed by Hermann von Helmholtz, that color perception depends upon the presence in the retina of three kinds of nerve fibers which respond respectively to red, green and violet light. This theory was experimentally proven in 1959, one hundred fifty eight years later!

While at Cambridge, Young performed his now famous double slit experiment where he passed a beam of light through two parallel slits in an opaque screen, forming a pattern of alternating light and dark bands on a white surface beyond which established that light was a transverse wave motion whose wavelength determined color (see wave interference). His findings were strongly opposed by contemporary scientists who believed that Newton, who had proposed that light was corpuscular in nature, would not possibly be wrong. However, Young’s work was soon confirmed by the French scientists, Fresnel and Arago.

In 1804, Young’s essay, “Cohesion of Fluids”, founded the theory of capillary phenomena on the principle of surface tension. He also observed the constancy of the angle of contact of a liquid surface with a solid, and showed how from these two principles to deduce the phenomena of capillary action (see Young-Laplace Equation and the Young-Dupre Equation). He went on to describe the characterization of elasticity that came to be known as Young’s Modulus.

After holding positions at St. George’s Hospital and on various scientific boards and committees, Thomas Young died in 1829 after a relatively short but distinguished career. His contemporary, Sir John Herschel, called him a “truly original genius”. Young being the first to define the term “energy” in the modern sense, was praised by Albert Einstein in his 1931 forward to an edition of Newton’s Opticks. Other admirers include physicist Lord Rayleigh and Nobel laureate Philip Anderson.