John William Strutt, Lord Rayleigh Biography

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World of Physics on John William Strutt, Lord Rayleigh

John William Strutt, who held the title Lord Rayleigh, received almost every honor available to a British scientist, including the Nobel Prize in physics in 1904. Lord Rayleigh never claimed that his methods were original, but he was very versatile in applying them. He specialized in technical physics, now called engineering physics. In his research, Rayleigh alternated between theory and experiment.

During his 50-year scientific career, Rayleigh published nearly 500 technical papers. He was professor at the Cavendish Laboratory at Cambridge University and later served as chancellor at Cambridge. Rayleigh was fellow, secretary and president of the Royal Society of London and received numerous honorary degrees from universities and science academies around the world. Early in his career, Lord Rayleigh started and helped to fund the Rayleigh farms and dairies that paid the family expenses during his academic career.

Rayleigh pursued classical physics in fields such as mechanics, dynamics, acoustics, and thermodynamics. Rayleigh looked at the classical nature of electricity and many of the advances that later took place in radio, electronics, and electrical engineering could be traced to Rayleigh's work. Rayleigh's style of research followed the pattern now used in computer analysis. He attacked a complex mathematical expression by breaking the expression into a series of terms and working only with the terms of the lowest order. Rayleigh moved to the next higher order only if the mathematical problem did not fit the observed data. In his calculations, Rayleigh used logarithms but never used a slide rule. It was not unusual for one problem to take as many as 50 handwritten pages. Perhaps because of the lengthy calculations required for physics research, Rayleigh was valued for his ability to go straight to the point and express it simply.

As of 2000, Rayleigh's theory of scattering was still taught in physics. The theory of scattering developed when Rayleigh observed that air molecules scatter light and this affects the way haze in the atmosphere can be measured.

Rayleigh's theory of sound, published in 1877, is useful for the study of acoustics, wave propagation, vibration, and periodic systems. The mathematical formulations used for wave mechanics are adaptations of Rayleigh's work on the theory of sound.

Rayleigh helped lay the groundwork for the quantum revolution. The Rayleigh-Jeans law, a classical formulation in blackbody radiation, worked for long wavelengths but not short ones. German physicist, Wilhelm Wien, developed an opposite theory that worked for short wavelengths but not long ones. Max Planck tried to make sense of the contradictory theories and this led to his discovery of the quantum in action. Rayleigh's research led to further developments in quantum mechanics such as the Rayleigh-Ritz approximation and the Schroedinger-Rayleigh method. In 1887, Lord Rayleigh assisted and advised Albert A. Michelson in the Michelson-Morley ether drift experiments which were a stepping stone to Einstein's relativity theory. While Rayleigh accepted the theory of relativity, his own studies were classical and nonrelativistic.

In 1895, Rayleigh isolated the element argon and gave equal credit to Sir William Ramsay.

Rayleigh won the 1904 Nobel Prize for his work on resolution limits. Using a model of the optical system, Rayleigh observed that a shorter wavelength and larger aperture result in a finer resolution. The smallest feature that can be resolved by an optical system with a circular aperture is in direct proportion to the wavelength of the light source when divided by the diameter of the lens aperture. Rayleigh's limit is useful to the semiconductor industry because the formula can be applied to determine the smallest transistors that can be put into a computer chip.

Rayleigh's six volumes of scientific papers were reprinted in 1964 as physicists continued using them. Rayleigh's continues to be read in the original and cited, whereas the work of most of his contemporaries is not. A memorial tablet in Westminster Abbey honors Rayleigh as "An unerring leader in the advancement of natural knowledge."