John William Strutt, 3rd Baron Rayleigh, OM, PC, PRS was a British scientist who made extensive contributions to both theoretical and experimental physics. He received the 1904 Nobel Prize in Physics “for his investigations of the densities of the most important gases and for his discovery of argon in connection with these studies.”

Rayleigh provided the first theoretical treatment of the elastic scattering of light by particles much smaller than the light’s wavelength, a phenomenon now known as “Rayleigh scattering”, which notably explains why the sky is blue. He studied and described transverse surface waves in solids, now known as “Rayleigh waves”. He contributed extensively to fluid dynamics, with concepts such as the Rayleigh number (a dimensionless number associated with natural convection), Rayleigh flow, the Rayleigh–Taylor instability, and Rayleigh’s criterion for the stability of Taylor–Couette flow. He also formulated the circulation theory of aerodynamic lift. In optics, Rayleigh proposed a well known criterion for angular resolution. His derivation of the Rayleigh–Jeans law for classical black-body radiation later played an important role in the birth of quantum mechanics (see Ultraviolet catastrophe). Rayleigh’s textbook The Theory of Sound (1877) is still used today by acousticians and engineers.

His education was repeatedly interrupted by ill-health. He spent three years in a private school at Wimbledon, and another short stay at Harrow, he finally spent four years with the Rev. George Townsend Warner (1857) who took pupils at Torquay. In 1861 he entered Trinity College, Cambridge.where, he graduated in the Mathematical Tripos in 1865.In 1866 he obtained a fellowship at Trinity which he held until 1871.

A severe attack of rheumatic fever in 1872 made him spend the winter in Egypt and Greece. After his father’s death, he now found himself compelled to devote part of his time to the management of his estates; later he handed over the estate management to his younger brother.
In 1879 he was appointed to follow James Clerk Maxwell as Professor of Experimental Physics and Head of the Cavendish Laboratory at Cambridge. In 1884 he left Cambridge to continue his experimental work at his country seat at Terling, Essex, and from 1887 to 1905 he was Professor of Natural Philosophy in the Royal Institution of Great Britain
He served for six years as President of a Government Committee on Explosives, and from 1896 to 1919 he was Scientific Advisor to Trinity House. He was Lord Lieutenant of Essex from 1892 to 1901.
Lord Rayleigh’s first researches were mainly mathematical, concerning optics and vibrating systems, but his later work ranged over almost the whole field of physics, covering sound, wave theory, colour vision, electrodynamics, electromagnetism, light scattering, flow of liquids, hydrodynamics, density of gases, viscosity, capillarity, elasticity, and photography. His patient and delicate experiments led to the establishment of the standards of resistance, current, and electromotive force; and his later work was concentrated on electric and magnetic problems. His Theory of Sound was published in two volumes during 1877-1878, and his other extensive studies are reported in his Scientific Papers – six volumes issued during 1889-1920.
He was President Royal Society from 1905 to 1908. He was awarded the Copley, Royal, and Rumford Medals of the Royal Society, and the Nobel Prize for 1904.