John Henry Poynting

Today is the birthday of physicist John Henry Poynting, born in Monton, England, in 1852. He started out teaching at Owens College (later Manchester University), where his students included future Nobel Prize winner J. J. Thomson. He then worked briefly under James Clerk Maxwell, who formulated electromagnetic theory, at Trinity College, Cambridge. In the mid-1880s Poynting made his own crucial contributions to electromagnetic theory. In a theorem that bears his name, Poynting developed a formula to describe the conservation of energy in an electromagnetic field. The rate that electromagnetic energy flows from a given point is assigned a value known as the Poynting vector. Poynting made many other scientific contributions both inside and outside of physics, including a study of public drunkenness.

Date in History: 9 September 1852