"I've now written Utrecht off, and dear Zurich can go take a running jump... – all except for you," wrote Albert Einstein on 15th November 1911 to a friend in Zurich. At the time he was professor in Prague. He had received the offer of a chair from the University of Utrecht, but had declined. He hoped to return to ETH – to the Polytechnicum, as it then was – where he had obtained his teacher's certificate in mathematics and physics. When finally a friend reports on an impending offer, Einstein fears that the powers in Zurich will turn to "wriggling" tactics: "When they hear about my renunciation of the chair at Utrecht, they'll immediately lose their temperament and keep me hanging on forever." Yet, on 8th December, Einstein received an official invitation to Zurich from the ETH Council. He became ETH Professor of Theoretical Physics.

Student years at the Poly

The relationship between Einstein and ETH were always complicated. In 1895 matriculation at the Polytechnicum was denied to the then 16-year-old Einstein. Insufficient knowledge of modern languages, zoology and botany was the reason given. Further education at the grammar school in the neighbouring canton Aargau was arranged. A year later, after passing his Matura exams, Einstein passed the admission exam at the Polytechnicum. He entered the year with four other students.

Electro-technical Laboratory at the Polytechnicum. (Picture: Archives ETH Library Zurich) large

One of his fellow students was Mileva Maric, of Serbian descent. Over the next few years she will go from being Einstein's "dear Miss Maric" to his "dearest Doxerl", and eventually become his first wife and mother of three children. Together with Mileva, Einstein often skipped lectures and course work. Instead, they passed their time in long discussions on the controversial works of Kirchhoff, Helmholtz, Hertz etc. Or Einstein went to the laboratory. "It's quite amazing that the revered curiosity of researchers hasn't been entirely strangled in the modern institutions of education. I think one could even take away the rapacious appetite of a wild animal if one were to use a whip to force it to eat all the time." Einstein only managed to hand in written tests that fell due thanks to the exact notes taken by another student, his close friend Marcel Grossmann. In the summer of 1900 Einstein thus succeeded in obtaining his first academic degree, his "Diploma", with a good average grade of 4.91.

His return as a "master"

In contrast to his fellow students, however, Einstein did not get an assistant's position after his graduation. He fell into a deep crisis and desperately sought work. "I will soon have honoured all physicists from the North Sea to the southern most point of Italy with my application!" Grossmann saves his bacon once again, through his father who arranges for a position at the Patent Office in Berne. "The biggest thing Marcel Grossmann did for me as a friend." Thanks to the security of a permanent job Einstein finds peace and time to work on some of his most important contributions to physics, like the theory of relativity..

It was the impression that this work made on the international community that finally led to his return to ETH in 1912. From Paris, Marie Curie wrote: "It will honour any university that is able to win the co-operation of this young master". The students are enthusiastic about his fresh, unusual teaching style. Einstein invites them into his home and spends long nights in discussions with them. "Don't set yourself goals that are too easy, gentlemen!"

Mileva Maric and Albert Einstein or: Doxerl and Johonzel (1911). (Picture: ETH Library Archives Zurich) large

Apart from his teaching duties, Einstein works incessantly on his general theory of relativity. "Oh! You know, whoever, like me, has to throw so much of what he's done into the paper-bin..." Once again, Marcel Grossmann, in the meantime also ETH professor, is a great help. He makes the mathematical tools accessible to Einstein, which the latter needs for his general relativity theory. In 1913 the two friends published their joint draft of a theory of gravitation. The conceptual groundwork for a general theory of relativity is already laid out in this work.

Goodbye most beautiful country

Then in November 1913 Einstein received an offer from Berlin. He was offered a princely salary and exempted from all teaching obligations. Three names stand behind the offer: Planck, Nernst and Warburg. Einstein's cousin, Elsa, with whom he was already having an affair, also lived in Berlin. Mileva moved to Berlin with him but, frustrated, returns to Switzerland after a few weeks.

Mileva and Einstein fail to resolve their differences and are divorced in 1919. In the same year, Einstein married Elsa. The move from cosy Zurich to the big city marked the beginning of what was possibly the greatest change in Einstein's life; from a promoter of the new physics, which interested only a few insiders, to an international icon of science, from remote researcher to one of the most influential personalities of society.

Beno Eckmann, retired ETH mathematics professor and one-time head of the Research Institute of Mathematics, experienced these exciting times at first hand. Eckmann's father already had known Einstein by sight, as an open, interested young man in Berne. A half a century later, Beno Eckmann himself saw the great man on campus in Princeton. Einstein "with his long hair and habitual pullover". Einstein, who hardly let any of Princeton's research elite get near to him. "At tea-time he only sat in a corner, talking to the mathematician, Gödel."

At that point in time, physics had been following a course for many years that was a long way away from Einstein's ideas. Quantum mechanics had radically shifted, once again, the paradigm of physics. Einstein obstinately repudiated these new developments and continued to work alone on a generalised field theory. These later works never found their way into the canons of physics. Only the theories that Einstein had already more or less developed when he left Zurich survive today in physics students' curricula.