John Arthur Jacobs

John Arthur “Jack” Jacobs (13 April 1916 – 13 December 2003) was a British geophysicist and mathematician, whose primary area of research was geomagnetism. He worked at multiple universities in Canada and the UK, and was awarded the Gold medal of the Royal Astronomical Society in 2002.

Early life and career Jacobs graduated from University College London, with an MA in mathematics in 1939 with specialism in higher mathematics and hydrodynamics.

In 1943, he became a lecturer of mathematics at Royal Holloway College, and was awarded his PhD degree in 1949 for research in plastic flow.

The University of British Columbia hired Jacobs as Professor of Physics in 1957 and within ten years he had created the Institute of Earth Sciences and the Department of Geophysics and Astronomy. He was also a Fellow of the AGU and a Fellow of the Royal Astronomical Society and was awarded the RAS's Price Medal in 1994, and the RAS Gold Medal in 2002.

He retired from the University of Cambridge in 1983 and later moved to Aberystwyth, Wales where his third wife Ann Grace Wintle

Scientific work Jacobs's published work runs to nearly 200 scientific papers and seven books which cover the temperature of the interior of the Earth, geomagnetic micropulsations, magnetic storms, the Earth's core and reversals of the Earth's magnetic field.

The citation for the RAS Gold Award highlights his proposal in 1956 for an adiabatic cooling model of the Earth, in which the Earth's liquid core slowly cools and freezes from the centre outwards to form the solid inner core (which had been shown to exist by seismic observations made in the 1930s). This proposal was made years before the idea of plate tectonics and before anyone had thought of the Earth losing heat by convection, let alone in an adiabatic state.