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]