William Kingdon Clifford

William Kingdon Clifford (1845 to 1879) was a British mathematician and philosopher, born in Exeter, who studied at King's College London and Trinity College, Cambridge, where he was elected a fellow in 1868 after finishing as Second Wrangler in 1867. Building on the work of Hermann Grassmann, he unified the quaternions with Grassmann's outer product and introduced what is now called geometric algebra, a special case of the Clifford algebra named in his honour. He was much impressed by Bernhard Riemann's 1854 essay on the hypotheses at the foundations of geometry, translated it for Nature in 1873, and speculated that gravitation might be a manifestation of an underlying geometry. Appointed professor of mathematics and mechanics at University College London in 1871 and elected a Fellow of the Royal Society in 1874, he also wrote on philosophy, coining the expressions mind-stuff and the tribal self. He died of tuberculosis on Madeira.