Einstein tried to persuade Adler to focus on science rather than be enticed into politics. “Be a little patient,” he said. “You will certainly be my successor in Zurich one day.” (Einstein was already assuming that he would move on to a more prestigious university.) But Adler ignored the advice and decided to become an editor at the Social Democratic Party newspaper. Loyalty to a party, Einstein felt, meant surrendering some independence of thought. Such conformity confounded him. “How an intelligent man can subscribe to a party I find a complete mystery,” Einstein later lamented about Adler.3
Einstein was also reunited with his former classmate and note-taker Marcel Grossmann, who had helped him get his job at the patent office and was now a professor of math at their old Polytechnic. Einstein would often visit Grossmann after lunch for help with the complex geometry and calculus he needed to extend relativity into a more general field theory.
Einstein was even able to forge a friendship with the other distinguished math professor at the Polytechnic, Adolf Hurwitz, whose classes he had often skipped and who had spurned his plea for a job. Einstein became a regular at the Sunday music recitals at Hurwitz’s home. When Hurwitz told him during a walk one day that his daughter had been given a math homework problem she did not understand, Einstein showed up that afternoon to help her solve it.4
As Kleiner predicted, Einstein’s teaching talents improved. He was not a polished lecturer, but instead used informality to his advantage. “When he took his chair in shabby attire with trousers too short for him, we were skeptical,” recalled Hans Tanner, who attended most of Einstein’s Zurich lectures. Instead of prepared notes, Einstein used a card-sized strip of paper with scribbles. So the students got to watch him develop his thoughts as he spoke. “We obtained some insight into his working technique,” said Tanner. “We certainly appreciated this more than any stylistically perfect lecture.”
At each step of the way, Einstein would pause and ask the students if they were following him, and he even permitted interruptions. “This comradely contact between teacher and student was, at that time, a rare occurrence,” according to Adolf Fisch, another who attended the lectures. Sometimes he would take a break and let the students gather around him for casual conversation. “With an impulsiveness and naturalness he would take students by the arm to discuss things,” recalled Tanner.
During one lecture, Einstein found himself momentarily stumped about the steps needed to complete a calculation. “There must be some silly mathematical transformation that I can’t find for a moment,” he said. “Can one of you gentlemen see it?” Not surprisingly, none of them could. So Einstein continued: “Then leave a quarter of a page. We won’t lose any time.”Ten minutes later, Einstein interrupted himself in the middle of another point and exclaimed, “I’ve got it.” As Tanner later marveled, “During the complicated development of his theme he had still found time to reflect upon the nature of that particular mathematical transformation.”
At the end of many of his evening lectures, Einstein would ask, “Who’s coming to the Cafe Terasse?” There, with an informal cadre on a terrace overlooking the Limmat River, they would talk until closing time.
On one occasion, Einstein asked if anyone wanted to come back to his apartment. “This morning I received some work from Planck in which there must be a mistake,” he said. “We could read it together.” Tanner and another student took him up on the offer and followed him home. There they all pored over Planck’s paper. “See if you can spot the fault while I make some coffee,” he said.
After a while, Tanner replied, “You must be mistaken, Herr Professor, there is no error in it.”
“Yes, there is,” Einstein said, pointing to some discrepancies in the data, “for otherwise that and that would become that and that.” It was a vivid example of Einstein’s great strength: he could look at a complex mathematical equation, which for others was merely an abstraction, and picture the physical reality that lay behind it.
Tanner was astounded. “Let’s write to Professor Planck,” he suggested, “and tell him of the mistake.”
Einstein had by then become slightly more tactful, especially with those he placed on a pedestal, such as Planck and Lorentz. “We won’t tell him he made a mistake,” he said. “The result is correct, but the proof is faulty. We’ll simply write and tell him how the real proof should run. The main thing is the content, not the mathematics.”5
Despite his work on his machine to measure electrical charges, Einstein had become a confirmed theorist rather than experimental physicist. When he was asked during his second year as a professor to supervise laboratory work, he was dismayed. He hardly dared, he told Tanner, “pick up a piece of apparatus for fear it might blow up.” To another eminent professor he confided, “My fears regarding the laboratory were rather well founded.”6
As he was finishing his first academic year at Zurich, in July 1910, Mari gave birth, again with difficulty, to their second son, named Eduard and called Tete. She was ill for weeks afterward. Her doctor, contending that she was overworked, suggested that Einstein find a way to make more money and pay for a maid. Mari
was annoyed and protective. “Isn’t it clear to anyone that my husband works himself half dead?” she said. Instead, her mother came down from Novi Sad to help.7
Throughout his life, Einstein would sometimes appear aloof toward his two sons, especially Eduard, who suffered from increasingly severe mental illness as he grew older. But when they were young, he tended to be a good father. “When my mother was busy around the house, father would put aside his work and watch over us for hours, bouncing us on his knee,” Hans Albert later recalled. “I remember he would tell us stories—and he often played the violin in an effort to keep us quiet.”
One of his strengths as a thinker, if not as a parent, was that he had the ability, and the inclination, to tune out all distractions, a category that to him sometimes included his children and family. “Even the loudest baby-crying didn’t seem to disturb Father,” Hans Albert said. “He could go on with his work completely impervious to noise.”
One day his student Tanner came for a visit and found Einstein in his study poring over a pile of papers. He was writing with his right hand and holding Eduard with his left. Hans Albert was playing with toy bricks and trying to get his attention. “Wait a minute, I’ve nearly finished,” Einstein said, as he handed Eduard to Tanner and kept scribbling his equations. “It gave me,” said Tanner, “a glimpse into his immense powers of concentration.”8
Einstein had been in Zurich less than six months when he received, in March 1910, a solicitation to consider a more prestigious job: a full professorship at the German part of the University of Prague. Both the university and the academic position were a step up; however, moving from the familiar and friendly Zurich to the less congenial Prague would be disruptive for his family. For Einstein, the professional considerations outweighed the personal ones.
He was again going through difficult periods at home. “The bad mood that you noticed in me had nothing to do with you,” he wrote to his mother, who was now living in Berlin. “To dwell on the things that depress or anger us does not help in overcoming them. One must knock them down alone.”
