John Poynting | |
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 John Henry Poynting | |
| Born | (1852-09-09)9 September 1852 Monton, Lancashire, England |
| Died | 30 March 1914(1914-03-30) (aged 61) Birmingham, England |
| Nationality | English |
| Alma mater | |
| Known for | Poynting vector Poynting effect Poynting's theorem Poynting–Robertson effect Term "Greenhouse Effect" Calculating the mass of the Earth |
| Awards |
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| Scientific career | |
| Fields | Physicist |
| Institutions | Mason Science College,University of Birmingham |
| Academic advisors | James Clerk Maxwell |
| Notable students | Francis William Aston;Alfred J. Lotka |
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John Henry PoyntingFRS[1] (9 September 1852 – 30 March 1914[2][3]) was an Englishphysicist. He was the first professor of physics atMason Science College from 1880 to 1900, and then the successor institution, theUniversity of Birmingham until his death.[4]
Poynting was the youngest son of Thomas Elford Poynting, aUnitarian minister. He was born at the parsonage of the Monton Unitarian Chapel in Eccles, Lancashire, where his father served as minister from 1846 to 1878. In his boyhood, he was educated at the nearby school operated by his father. From 1867 to 1872, he attendedOwens College, now theUniversity of Manchester, where his physics teachers includedOsborne Reynolds andBalfour Stewart. From 1872 to 1876 he was a student at theUniversity of Cambridge, where he attained high honours in mathematics after taking grinds withEdward Routh.
In the late 1870s, he worked in theCavendish Laboratory at Cambridge underJames Clerk Maxwell.[5] In 1880, he became the first professor of physics at theUniversity of Birmingham. He was the developer andeponym of thePoynting vector, which describes the direction and magnitude ofelectromagnetic energy flow and is used in thePoynting theorem, a statement about energy conservation forelectric andmagnetic fields. This work was first published in 1884. He performed a measurement ofNewton'sgravitational constant by innovative means during 1893. In 1903 he was the first to realise that theSun's radiation can draw in small particles towards it:[6] this was later named thePoynting–Robertson effect.
He discovered the torsion-extension coupling infinite strain elasticity. This is now known as the (positive)Poynting effect in torsion.
Poynting and the Nobel prizewinnerJ. J. Thomson co-authored a multi-volume undergraduate physics textbook, which was in print for about 50 years and was in widespread use during the first third of the 20th century.[7] Poynting wrote most of it.[8]
He was awarded anhonorary MSc in Pure Science in 1901 byBirmingham University.[9]
Poynting lived at 11 St Augustine's Road,Edgbaston with his family and servants for some years. He previously lived at 66 Beaufort Road,Edgbaston (demolished) and died of a diabetic coma[citation needed], aged 61, at 10 Ampton Road, Edgbaston in 1914. In 1880, he married Maria Adney Cropper. He was survived by his widow, a son, and two daughters.[10]
Alfred J. Lotka was among Poynting's most famous students, being inspired by Poynting to apply the ideas ofphysical chemistry to biology. Lotka dedicated his classic book on mathematicalpopulation biology to Poynting.Poynting predicted the 'Poynting-Robertson effect', whereby a particle of dust orbiting a star experiences a drag force which makes it spiral slowly into the star.Howard P. Robertson later restated the prediction usinggeneral relativity.Poynting also founded and is the namesake of the popular student society at the University of Birmingham, 'The Poynting Physical Society' or PPS.[11]
Craters onMars and theMoon are named in his honour, as is the main physics building at theUniversity of Birmingham and the departmental society there, the Poynting Physical Society.He is credited with coining the expression "greenhouse effect" in 1909 to explain how infrared-absorbing trace gasses such as carbon dioxide in the atmosphere increases the surface temperature of Earth and Mars.[12]
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