From 1900 to 1909, Abraham worked at Göttingen as a privatdozent, an unpaid lecturing position. Abraham developed his theory of the electron in 1902, in which he hypothesized that the electron was a perfect sphere with a charge divided evenly around its surface. Abraham's model was competing with that developed by Hendrik Lorentz (1899, 1904) and Albert Einstein (1905) which seem to have become more widely accepted; nevertheless, Abraham never gave up his model, since he considered it was based on "common sense". Abraham was a staunch opponent of the theory of relativity.[2]
When World War I started, Abraham was forced to return to Germany. During this time he worked on the theory of radio transmission. After the war, he still was not allowed back into Milan, so until 1921 he worked at Stuttgart as the professor of physics at Technische Hochschule.
After his work at Stuttgart, Abraham accepted the position of chair in Aachen; however, before he started his work there he was diagnosed with a brain tumor. He died on 16 November 1922 in Munich, Germany.
After his death, Max Born and Max von Laue wrote about him in an obituary: He loved his absolute aether, his field equations, his rigid electron just as a youth loves his first flame, whose memory no later experience can extinguish.[3]
