Lord Rayleigh
Rayleigh, Lord (1842-1919) was a British physicist who made many important discoveries in a wide variety of fields. He received the Nobel Prize in physics in 1904 for studying the density of gases and for discovering and isolating the chemical element argon. Argon is a colorless, odorless, tasteless gas element that forms 0.94 percent of the earth's atmosphere. Lord Rayleigh and William Ramsay discovered it in 1894.
Rayleigh worked in many fields, initially concentrating on mathematical investigations of optics and vibrating systems, and later looking at almost the whole range of physics. His research included studies of sound, wave theory, color vision, electrodynamics (the study of electric currents), electromagnetism, light scattering, and the density of gases. He also studied viscosity (the resistance of a liquid to changing its shape), capillarity (the movement of the surface of a liquid, caused by surface tension), elasticity, and photography. His work led to the setting up of standards for the measurement of current, electromotive force, and resistance.
John William Strutt was born on Nov. 12, 1842, in Essex, England, the son of John James Strutt, the Baron Rayleigh of Terling Place, Witham, in Essex. The family were landowners. Serious illnesses frequently interrupted young Rayleigh's education. His early schooling included a brief period at Eton College, a private school at Wimbledon, a stay at Harrow School, as well as four years of private tutoring. In 1861, Rayleigh went on to Trinity College, Cambridge, graduating in mathematics in 1865.
In 1871, Rayleigh married Evelyn Balfour, the sister of Arthur James Balfour, Earl of Balfour, who became a leader of the United Kingdom's Conservative Party for more than 20 years. Rayleigh remained politically connected, serving in various advisory roles through the years.
In 1871, Rayleigh accurately explained why the sky is blue. The colors of the sky result from the scattering of sunlight by the gas molecules and dust particles in the atmosphere. Sunlight consists of light waves of varying wavelengths, each of which is seen as a different color. The shortest light waves appear blue and the longest red. The blue light waves are readily scattered by tiny particles of matter in the atmosphere, but the red light waves travel undisturbed unless they are struck by larger particles. When the sky is clear, the waves of blue light are scattered much more than those of any other color. As a result, the sky appears blue.
Inheriting his family title after his father's death, he became Baron Rayleigh in 1873. That year, he also became a fellow of the Royal Society. He served as its president from 1905 to 1908.
Rayleigh set up a laboratory at his home estate at Terling, where he was to make many of his discoveries. He wrote the standard work The Theory of Sound (1877-1878).
He served as professor of experimental physics at Cambridge from 1879 to 1884. He helped make the Cavendish Laboratory in Cambridge a world-famous research center and developed laboratory courses in heat, electricity and magnetism, properties of matter, optics, and acoustics.
One of his most important accomplishments during his time as a Cavendish professor was the precise redetermination of the electrical units the ohm, the ampere, and the volt. The ohm is the unit used to measure resistance to the passage of an electric current. The international standard for the ohm was adopted in 1893. An ampere is the unit used to measure the rate of flow of an electric current. It is one of seven base units in the metric system. The volt is a unit of electric measurement that measures the ability of an electric field to give energy to electric charges.
In 1884, he resigned his chair at Cambridge to return to research at his home laboratory. He continued to research a wide range of subjects including light and sound radiation, thermodynamics, electromagnetism, and mechanics. He held a position as professor of natural philosophy at the Royal Institution from 1887 to 1905.
Rayleigh discovered that nitrogen from the atmosphere had a somewhat greater density than artificially produced nitrogen. He guessed, as did Ramsay, that this difference pointed to the presence of an unknown gas in the atmosphere. Ramsay experimented in 1894, and found the unknown gas. Ramsay named the gas argon, from the Greek word meaning inert. Inert gases do not readily react with other elements.
In 1904, Rayleigh received the Nobel Prize in physics and Ramsay received the Nobel Prize in chemistry for their work on gases and the discovery of argon. He received the Rumford Medal in 1920.