Einstein in 1912.
Through letters, visits, and science
meetings, Einstein came to know most of the major physicists
of Europe (there were not many in those days). In 1912
Einstein was invited back to the Swiss Federal Institute
of Technology as professor. Here he rejoined his old friend
Marcel Grossmann, now professor of mathematics. With Grossmann's
aid, Einstein studied the mathematical theories and techniques
which he found necessary for his work toward a new theory
of gravitation. Meanwhile, Einstein was being introduced
to a different sort of world by another friend, Friedrich
Adler: the world of the Second International and its attempt
to halt the growth of international rivalries in Europe.
In 1914, the German government gave Einstein a senior
research appointment in Berlin, along with a membership
in the prestigious Prussian Academy of Sciences. When
Einstein had left his native land as a youth, he had renounced
German citizenship and all of the militarist German society.
But Berlin -- with no teaching duties and a galaxy of
top scientists for colleagues -- could not be resisted.
It was the highest level a scientific career could ordinarily
"With such fame, not much time remains for his wife," Mileva
complained. "I am very starved for love." Einstein felt suffocated
in the increasingly strained and gloomy relationship. He found
solace in a love affair with his cousin, Elsa Löwenthal.
Mileva and Albert separated in 1914, after bitter arguments,
and divorced in 1919. That same year he married Elsa, and
settled in with her and her two grown daughters by a previous
marriage. "The Lord has put into him so much that's beautiful,
and I find him wonderful," Elsa later wrote, "even though
life at his side is enervating and difficult." (Click here
for more on Einstein at home.)