Gravitational magnetism was proposed by the German - British physicist Arthur Schuster as an explanation for the magnetic field of the Earth, but was found nonexistent in a 1923 experiment by H. A. Wilson. The hypothesis was revived by the British physicist P. M. S. Blackett in 1947 when he proposed that a rotating body should generate a magnetic field proportional to its angular momentum. This was never generally accepted, and by the 1950s even Blackett felt it had been refuted.