The great Sir Isaac Newton was never convinced that he really understood how gravity worked. If Einstein could develop his own ideas about invisible channels in Space guiding our every movement, including our tumbling falls in gravity, he would have surpassed Newton.
This was a fabulous prospect. In a major review article in 1907, he began to expand his 1905 work on special relativity to include some of these new thoughts on gravity, but he had to stop before he’d properly developed his ideas. The Patent Office was proving to be an impossible place to work. This wasn’t because he was overly delicate about needing silence to concentrate. Even among a noisy group, Einstein had the ability to, as Maja described it, “withdraw to the sofa, take pen and paper in hand, set the inkstand precariously on the armrest, and lose himself . . . in a problem.” At one point when he was in his twenties, a visitor to Einstein’s apartment described him sitting in a big chair, rocking his child in his left hand, writing his equations on a flat surface with his right hand, and keeping a cigar lit as he puffed away over infant, equations, and new visitor alike.
The links between Space and Things, however, were just too much to work out in those scattered evening hours available to him. Sometimes he could still evade Superintendent Haller and sneak open the drawer of his desk to take out papers from his self-styled Department of Theoretical Physics. But Haller seemed to be keeping a stricter eye on his clerks, and far too often Einstein had to slam his drawer shut before he’d had time to do any serious work.
There was also now another, more personal reason for seeking a better job. Although von Laue’s visit in 1907 hadn’t led to another position, as 1907 turned into 1908, Einstein’s reputation was growing, and more visitors were starting to come. These weren’t like the friends he and Marić had acquired together in their first years of marriage—friends they would stroll or share meals with. Nor were they like Grossmann, from the Polytechnic, with whom the couple could reminisce about their student days. The new visitors came to talk to Einstein, and to him alone.
Marić was no longer a fellow science student, far brighter and more educated than almost any other woman they knew. She was merely Mrs. Einstein, to be treated politely as she served beer or tea, but then ignored.
That was hard for Marić. She wasn’t at Marcel Grossmann’s level of mathematical dexterity, but she’d been a strong student, quite comfortable with advanced calculus, statistical mechanics, and the like. At that time, she and Einstein had dreamed of working together. Even as late as 1905, she had checked the most important of his articles, since he trusted her sharp eye for mathematical errors. When the last paper was finished, they had gone out and celebrated not like earnest parents, but like exuberant students again, as their card about ending up dead drunk showed.
Marić tried to fight her sadness at the change, writing to a girlfriend: “With that kind of fame, he does not have much time left for his wife . . . But what can you do?” It must also have hurt that a husband-and-wife team, the Curies, in Paris, had just won the Nobel Prize—exactly the dream that had had to be put aside when Marić needed so much time taking care of her and Einstein’s son.
More money for child care would only help to free up both Einstein and Marić for the work they craved. So in the end, Einstein swallowed his pride and contacted the University of Bern again. They had rejected his first application for a teaching post, since his submission of the special theory of relativity didn’t fit their requirements. Now he submitted the more conventional dissertation they wanted, and was accepted to give the very lowest level of lectures. There would be no pay, aside from what students who attended his lectures might contribute. He still had to continue at the Patent Office, but it was a start.
His first class was in the spring of 1908, meeting on Tuesday and Saturday at the desperately early hour of 7 a.m. When it looked as if no one would show up, the ever loyal Michele Besso, as well as two more friends from the Patent Office, decided to attend. Once the day’s lecture was done, he would join them to grab a quick coffee, then hurry down the hill to work.
In the winter term the following year, they were joined by a real student, which was pretty exciting, but when that student quit it seems that Einstein’s sister, Maja, promptly showed up to the lectures to keep the university authorities from canceling her brother’s course. She understood not a word of what he said, and since Einstein wasn’t going to charge Besso or his sister, money at home remained tight. “Isn’t it clear to anyone that my husband works himself half dead?” Marić loyally replied when a friend commented that they should hire a maid so that she could have more free time.
Thankfully, before long news came that a properly paid position might be available at the University of Zurich, just sixty miles away. That, however, required having a professor from Zurich come and watch Einstein lecture. This was a worry. For Einstein it was always hit-or-miss whether he would give a good lecture, “due to my poor memory.” When the great day arrived and Einstein got home afterward, Marić asked how it had gone. The news wasn’t good. “Being investigated got on my nerves,” he explained. “I really did not lecture divinely.”
Eventually Zurich relented, largely because an ever greater number of physicists across Europe were recognizing the strength of Einstein’s papers. Moreover, when the in-house physics candidate realized that the faculty might still reject Einstein, that candidate—Friedrich Adler, an old acquaintance from Polytechnic days—to his credit stepped back: “If it is possible to get a man like Einstein for our university, it would be absurd to appoint me.”
So it was in 1909 that, after a biblical seven years of servitude, Einstein finally was able to leave the kingdom of the patent slaves and take up his first proper academic job at a university. Haller seems to have been almost entirely oblivious to Einstein’s growing fame, and in line with standard bureaucratic work had merely promoted him to the position of Technical Expert Second Class, although before Einstein left—perhaps in an effort to keep him on?—he hinted that the exalted heights of Technical Expert First Class might someday be within reach. By leaving Haller’s office, however, Einstein would now, at last, be able to continue his investigation: to see if the universe’s deepest parts really were linked, by curves or paths that no one had imagined before.
SIX
Time to Think
IN 1909, THE YEAR he moved from the Patent Office to the University of Zurich, Einstein was thirty; Marić was thirty-four. Bern had been attractive, but it was also isolating: it was really just an overgrown small town. Zurich was a true city, and many of their friends from Polytechnic days still lived there. That fact alone seemed to bode well.
The move proved rejuvenating, and for a while life was as thrilling as when they had first been married. They met Carl Jung, which could have been excellent for Marić, as her first interest, before physics, had been medicine, and so they potentially had a lot in common. But when Jung invited the Einsteins over for dinner, he largely ignored Marić and just focused on Einstein, trying to convince him of his own psychological ideas. Einstein didn’t enjoy that, and they never went back.
The Einsteins had better luck with a specialist in forensic medicine at the university, Heinrich Zangger, an ingenious man—one of the founders of emergency room medicine—whose range of interests greatly impressed Einstein. Better still, the Einsteins moved into the same block as the family of Albert’s academic advocate Friedrich Adler, who noted the good mood in the couple’s apartment. “We are on very good terms with [the Einsteins], who live above us,” Friedrich wrote his father. “. . . They run a Bohemian household.”
The University of Zurich salary was better than that at the Patent Office, but Einstein and Marić both knew it was important he didn’t get fired for lecturing poorly. He still dressed differently from the other faculty members in Zurich, with his trousers too short and his hair rumpled, but both he and Marić liked the idea that they were far from an ordinary, bourgeois couple. Einstein prepared his lectures more thoroughly th
an in Bern, and instead of trusting his poor memory, one student remembered that Dr. Einstein brought “a scrap of paper the size of a visiting card, on which he outlined the ground he intended to cover with us.”
Most of all, Einstein treated his students kindly. Europe before the First World War had strict hierarchies, and professors didn’t invite questions, certainly not from ordinary students. Einstein, however, had always scorned people who put on airs because their social status allowed it. Here in Zurich, he encouraged his students to interrupt him whenever they had a question; he invited them to coffeehouses after class to continue the conversations, or just to get to know them; often he’d bring them home to share his latest research. They liked it. He also always stood up against bullying. One student, a few years later, remembered how nervous she had been before delivering a seminar. Einstein gave her a reassuring nod from the audience, as if to say “Go ahead, you’ll be fine.” When a brash male student tried to score points by putting her down, Einstein stopped him, saying, “Clever, but not true,” and then encouraged her to continue.
The Einstein family’s new Zurich apartment was bigger than the one in Bern, and with that space, plus their renewed affection, they soon had a second child, named Eduard. One visiting student remembered that when the two boys made too much noise for Einstein to concentrate, the young professor would smile, reach for his violin—this good dad’s surefire weapon—and put them at ease by playing their favorite tunes. He and Marić called their sons die Barchën, “the little bears.”
In 1911 a better job came up, at the German University in Prague, and so the family moved again. Here Einstein’s salary stretched to a truly grand apartment—their first with electric lights—and he had even more time, between his administrative duties, simply to think.
Prague was in some ways a respite for Einstein, but it was far less pleasant for the German-speaking Slavic Marić, not least because of the standoff between German speakers and Czech speakers in the city. Czech nationalism was growing, but the German minority had control of many senior positions. Czechs who were perfectly bilingual often refused to speak German, to discomfit those, like Marić, who dared to try shopping in their city without knowing Czech; German speakers, even more ominously, took to disparaging all Slavs, which of course included Marić. The very fact that there was a “German University” demonstrated the problem, for it had been created when a separate “Czech University” split off from the same faculty, and now—although Einstein made a point of opening his lecture to Czech students—most professors refused to speak to anyone at the opposing university. There was a small Jewish literary crowd in the city that tried to stay neutral. It was at one of their salons that Einstein met Franz Kafka, although it seems that Kafka was too shy to say anything to this easygoing, already respected foreigner. What they might have talked about otherwise, we can only imagine.
PRAGUE MAY NOT have been the easiest place for the Einsteins to live, but at least there Albert was able to take his thought experiments further. He already had some idea that space itself was distorted in some way, which would explain what he was imagining about gravity, but he couldn’t yet work out the details. He also had some notion that because of these distortions, distant starlight would curve if it traveled near the sun, but he couldn’t be entirely sure about the details of that either.
One thing that helped, curiously enough, came from a genre of adventure stories in which a heroic explorer gets drugged, then wakes up bewildered and has little time to work out where he is. Einstein used that idea. Suppose, he imagined, that someone did wake up in a closed room with no windows: that he had been drugged and has no memory of how he got there. He can’t feel any gravity; he’s just floating in the room.
Is there any way that he can discover where he is?
One possibility, the heroic explorer would realize, is that he’s somewhere in distant space, out beyond the solar system and away from any large, bulky source of gravity such as our sun or even Jupiter. But another possibility is that he might just be in a building’s elevator, like those in the new skyscrapers then being built in America, and a dastardly villain has cut the cable, so he’s dropping from the very top of the elevator shaft. If the room is totally enclosed, and he’s floating freely, he can’t tell which it is. This is like the workers whom Einstein had imagined falling from the rooftop in Bern. When they’re in the air, unable to look around or feel the air’s movement, all they know is that they’re weightless. Whether they’re miles up or just inches from the ground, they cannot tell.
There is a way, however, Einstein now realized, that our intrepid hero can work out where he is, without being able to peer outside his sealed room. All he needs are two apples. He places one apple in each hand, spreads his arms out, and then lets the apples go.
If the two apples stay hovering perfectly still, he will know that he really is far away, in the distant vastness of outer space, far from any rock-jagged planets. He will have plenty of time to build an engine and get himself to safety.
But if the hero lets go of the apples, and instead of hovering in position, they ever so slowly, but ever so definitely, start gliding toward him—if he knows it’s not an air current doing that, or his own tense exhalations—then he will realize he’s in serious trouble. There’s only one thing that can make two apples that begin quite parallel with him eerily begin to approach him. There has to be a central source of gravity somewhere below, one that each apple is aiming for from its own starting point:
One can see the effect more strongly if one imagines him above the earth:
The conclusion is unfortunate, but also unambiguous. When the same effect happens in miniature, it’s clear that our hero must be in the free-falling elevator. At any moment now, he, the apples, and the entire room are going to most painfully impact upon the ground.
Looking at how the apples move is an ingenious way for the explorer to deduce if he’s moving toward a gravitational source like our planet, or if he’s far away in distant space. But there’s a conundrum. He feels no force whatsoever while he’s free-floating. Yet something is making the equally free-floating apples move toward him, and if he feels no force, it’s natural to think that they feel no force either.
How can the empty space inside an imagined elevator lead objects such as free-floating apples to start gliding toward each other, even though, to the explorer there with them, they obviously are just suspended in empty air?
In grappling with this problem, Einstein was learning a lot about his own creative process. Thinkers have often been classified as either golfers or tennis players. The golfers work on their own; the tennis players need interplay. Newton was a golfer; Watson and Crick—like many composers and lyricists—were tennis players. Einstein had been a golfer long enough. He could make some progress on this problem on his own, but he needed to collaborate if he was going to get any further.
Who could Einstein turn to? Marić couldn’t help, for although she had been able to check his earlier papers, having reached a good understanding of mathematics and physics in her undergraduate studies at the Zurich Polytechnic, this problem went far beyond what either of them had learned there. Besso would be out for the same reason, for although he had been, as Einstein put it, “the best sounding board in Europe,” his lack of ambition and whimsical attitude toward serious study meant that he, too, didn’t know enough, or wouldn’t learn enough, to be helpful.
The person Einstein really needed on the long, slow path that would lead him to general relativity was Marcel Grossmann, his friend and the fellow student who’d offered him lecture notes back when they were both undergraduates. After a stint as a high school teacher, Grossmann had gone to graduate school to study advanced mathematics, and since then he had stayed in academia, ending up as a math professor at their old Zurich Polytechnic, which had recently been upgraded to a full university and was now known by its German initials as ETH. The two men had been in touch a few times in the decade since, as when Grossmann hel
ped Einstein get a job at the Bern Patent Office or assisted with his friend’s abortive high school teaching applications, but mostly they had slipped apart. Einstein, however, still had the greatest respect for his talents. If a position could be had back in Switzerland, Einstein could benefit from being close to him.
The Einsteins had an additional and personal reason for planning a move. Leaving their Zurich friends behind had put too much pressure on their marriage. The coolness they had experienced in Prague from both Czechs and German speakers hadn’t helped either, and both Einstein and Marić were feeling the distance. When a big conference had come up in Brussels, one bringing most of Europe’s top physicists together, Einstein hadn’t brought Marić, even though she could have been in the company of the great minds there she so admired: Ernest Rutherford from Manchester, Max Planck from Berlin, and, of course, the successful female physicist she had never had the chance to try to become, Marie Curie from Paris. Marić wrote her husband while he was away, the letter carried by the fast steam trains that crossed the continent: “I would have loved only too much to have listened a little, and to have seen all those fine people. It has been an eternity since we have seen each other . . . Will you still recognize me?”
Perhaps returning to Zurich would bring back the warmth they’d had before. Marić was only too happy, accordingly, when Einstein arranged a faculty post for himself at ETH, the institution that just a short time ago had wanted no part of him. The family packed and in 1912 moved back.
Shortly after they reached Zurich, Einstein burst into his friend’s study and said, “Grossmann, Du musst mir helfen, sonst werd’ ich verrückt! (Grossmann, you’ve got to help me, or I’ll go crazy!)” Grossmann was willing to oblige. Einstein now had a convenient position at ETH, the old Polytechnic, right next to his old friend and supporter—and, now, fellow teacher as well.
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