The Zurich Polytechnic, with 841 students, was mainly a teachers’ and technical college when 17-year-old Albert Einstein enrolled in October 1896. It was less prestigious than the neighboring University of Zurich and the universities in Geneva and Basel, all of which could grant doctoral degrees (a status that the Polytechnic, officially named the Eidgenössische Polytechnische Schule, would attain in 1911 when it became the Eidgenössische Technische Hochschule, or ETH). Nevertheless, the Polytechnic had a solid reputation in engineering and science. The head of the physics department, Heinrich Weber, had recently procured a grand new building, funded by the electronics magnate (and Einstein Brothers competitor) Werner von Siemens. It housed showcase labs famed for their precision measurements.

Einstein was one of eleven freshmen enrolled in the section that provided training “for specialized teachers in mathematics and physics.” He lived in student lodgings on a monthly stipend of 100 Swiss francs from his Koch family relatives. Each month he put aside 20 of those francs toward the fee he would eventually have to pay to become a Swiss citizen.¹

Theoretical physics was just coming into its own as an academic discipline in the 1890s, with professorships in the field sprouting up across Europe. Its pioneer practitioners—such as Max Planck in Berlin, Hendrik Lorentz in Holland, and Ludwig Boltzmann in Vienna—combined physics with math to suggest paths where experimentalists had yet to tread. Because of this, math was supposed to be a major part of Einstein’s required studies at the Polytechnic.

Einstein, however, had a better intuition for physics than for math, and he did not yet appreciate how integrally the two subjects would be related in the pursuit of new theories. During his four years at the Polytechnic, he got marks of 5 or 6 (on a 6-point scale) in all of his theoretical physics courses, but got only 4s in most of his math courses, especially those in geometry. “It was not clear to me as a student,” he admitted, “that a more profound knowledge of the basic principles of physics was tied up with the most intricate mathematical methods.”²

That realization would sink in a decade later, when he was wrestling with the geometry of his theory of gravity and found himself forced to rely on the help of a math professor who had once called him a lazy dog. “I have become imbued with great respect for mathematics,” he wrote to a colleague in 1912, “the subtler part of which I had in my simple-mindedness regarded as pure luxury until now.” Near the end of his life, he expressed a similar lament in a conversation with a younger friend. “At a very early age, I made an assumption that a successful physicist only needs to know elementary mathematics,” he said. “At a later time, with great regret, I realized that the assumption of mine was completely wrong.”³

His primary physics professor was Heinrich Weber, the one who a year earlier had been so impressed with Einstein that, even after he had failed his entrance exam to the Polytechnic, he urged him to stay in Zurich and audit his lectures. During Einstein’s first two years at the Polytechnic, their mutual admiration endured. Weber’s lectures were among the few that impressed him. “Weber lectured on heat with great mastery,” he wrote during their second year. “One lecture after another of his pleases me.” He worked in Weber’s laboratory “with fervor and passion,” took fifteen courses (five lab and ten classroom) with him, and scored well in them all.⁴

Einstein, however, gradually became disenchanted with Weber. He felt that the professor focused too much on the historical foundations of physics, and he did not deal much with contemporary frontiers. “Anything that came after Helmholtz was simply ignored,” one contemporary of Einstein complained. “At the close of our studies, we knew all the past of physics but nothing of the present and future.”

Notably absent from Weber’s lectures was any exploration of the great breakthroughs of James Clerk Maxwell, who, beginning in 1855, developed profound theories and elegant mathematical equations that described how electromagnetic waves such as light propagated. “We waited in vain for a presentation of Maxwell’s theory,” wrote another fellow student. “Einstein above all was disappointed.”⁵

Given his brash attitude, Einstein didn’t hide his feelings. And given his dignified sense of himself, Weber bristled at Einstein’s ill-concealed disdain. By the end of their four years together they were antagonists.

Weber’s irritation was yet another example of how Einstein’s scientific as well as personal life was affected by the traits deeply bred into his Swabian soul: his casual willingness to question authority, his sassy attitude in the face of regimentation, and his lack of reverence for received wisdom. He tended to address Weber, for example, in a rather informal manner, calling him “Herr Weber” instead of “Herr Professor.”

When his frustration finally overwhelmed his admiration, Professor Weber’s pronouncement on Einstein echoed that of the irritated teacher at the Munich gymnasium a few years earlier. “You’re a very clever boy, Einstein,” Weber told him. “An extremely clever boy. But you have one great fault: you’ll never let yourself be told anything.”

There was some truth to that assessment. But Einstein was to show that, in the jangled world of physics at the turn of the century, this insouciant ability to tune out the conventional wisdom was not the worst fault to have.⁶

Einstein’s impertinence also got him into trouble with the Polytechnic’s other physics professor, Jean Pernet, who was in charge of experimental and lab exercises. In his course Physical Experiments for Beginners, Pernet gave Einstein a 1, the lowest possible grade, thus earning himself the historic distinction of having flunked Einstein in a physics course. Partly it was because Einstein seldom showed up for the course. At Pernet’s written request, in March 1899 Einstein was given an official “director’s reprimand due to lack of diligence in physics practicum.”⁷

Why are you specializing in physics, Pernet asked Einstein one day, instead of a field like medicine or even law? “Because,” Einstein replied, “I have even less talent for those subjects. Why shouldn’t I at least try my luck with physics?”⁸

On those occasions when Einstein did deign to show up in Pernet’s lab, his independent streak sometimes got him in trouble, such as the day he was given an instruction sheet for a particular experiment. “With his usual independence,” his friend and early biographer Carl Seelig reports, “Einstein naturally flung the paper in the waste paper basket.” He proceeded to pursue the experiment in his own way. “What do you make of Einstein?” Pernet asked an assistant. “He always does something different from what I have ordered.”

“He does indeed, Herr Professor,” the assistant replied, “but his solutions are right and the methods he uses are of great interest.”⁹

Eventually, these methods caught up with him. In July 1899, he caused an explosion in Pernet’s lab that “severely damaged” his right hand and required him to go to the clinic for stitches. The injury made it difficult for him to write for at least two weeks, and it forced him to give up playing the violin for even longer. “My fiddle had to be laid aside,” he wrote to a woman he had performed with in Aarau. “I’m sure it wonders why it is never taken out of the black case. It probably thinks it has gotten a stepfather.”¹⁰ He soon resumed playing the violin, but the accident seemed to make him even more wedded to the role of theorist rather than experimentalist.

Despite the fact that he focused more on physics than on math, the professor who would eventually have the most positive impact on him was the math professor Hermann Minkowski, a square-jawed, handsome Russian-born Jew in his early thirties. Einstein appreciated the way Minkowski tied math to physics, but he avoided the more challenging of his courses, which is why Minkowski labeled him a lazy dog: “He never bothered about mathematics at all.”¹¹

Einstein preferred to study, based on his own interests and passions, with one or two friends.¹² Even though he was still priding himself on being “a vagabond and a loner,” he began to hang around the coffee-houses and attend musical soirees with a congenial crowd of bohemian soul mates and fellow students. Despite his reputation for detachment, he forged lasting intellectual friendships in Zurich that became important bonds in his life.

Among these was Marcel Grossmann, a middle-class Jewish math wizard whose father owned a factory near Zurich. Grossmann took copious notes that he shared with Einstein, who was less diligent about attending lectures. “His notes could have been printed and published,” Einstein later marveled to Grossmann’s wife. “When it came time to prepare for my exams, he would always lend me those notebooks, and they were my savior. What I would have done without these books I would rather not speculate on.”

Together Einstein and Grossmann smoked pipes and drank iced coffee while discussing philosophy at the Café Metropole on the banks of the Limmat River. “This Einstein will one day be a great man,” Grossmann predicted to his parents. He would later help make that prediction true by getting Einstein his first job, at the Swiss Patent Office, and then aiding him with the math he needed to turn the special theory of relativity into a general theory.¹³

Because many of the Polytechnic lectures seemed out of date, Einstein and his friends read the most recent theorists on their own. “I played hooky a lot and studied the masters of theoretical physics with a holy zeal at home,” he recalled. Among those were Gustav Kirchhoff on radiation, Hermann von Helmholtz on thermodynamics, Heinrich Hertz on electromagnetism, and Boltzmann on statistical mechanics.

He was also influenced by reading a lesser-known theorist, August Föppl, who in 1894 had written a popular text titled Introduction to Maxwell’s Theory of Electricity. As science historian Gerald Holton has pointed out, Föppl’s book is filled with concepts that would soon echo in Einstein’s work. It has a section on “The Electrodynamics of Moving Conductors” that begins by calling into question the concept of “absolute motion.” The only way to define motion, Föppl notes, is relative to another body. From there he goes on to consider a question concerning the induction of an electric current by a magnetic field: “if it is all the same whether a magnet moves in the vicinity of a resting electric circuit or whether it is the latter that moves while the magnet is at rest.” Einstein would begin his 1905 special relativity paper by raising this same issue.¹⁴

Einstein also read, in his spare time, Henri Poincaré, the great French polymath who would come tantalizingly close to discovering the core concepts of special relativity. Near the end of Einstein’s first year at the Polytechnic, in the spring of 1897, there was a mathematics conference in Zurich where the great Poincaré was due to speak. At the last minute he was unable to appear, but a paper of his was read there that contained what would become a famous proclamation. “Absolute space, absolute time, even Euclidean geometry, are not conditions to be imposed on mechanics,” he wrote.¹⁵

One evening when Einstein was at home with his landlady, he heard someone playing a Mozart piano sonata. When he asked who it was, his landlady told him that it was an old woman who lived in the attic next door and taught piano. Grabbing his violin, he dashed out without putting on a collar or a tie. “You can’t go like that, Herr Einstein,” the landlady cried. But he ignored her and rushed into the neighboring house. The piano teacher looked up, shocked. “Go on playing,” Einstein pleaded. A few moments later, the air was filled with the sounds of a violin accompanying the Mozart sonata. Later, the teacher asked who the intruding accompanist was. “Merely a harmless student,” her neighbor reassured her.¹⁶

Music continued to beguile Einstein. It was not so much an escape as it was a connection: to the harmony underlying the universe, to the creative genius of the great composers, and to other people who felt comfortable bonding with more than just words. He was awed, both in music and in physics, by the beauty of harmonies.

Suzanne Markwalder was a young girl in Zurich whose mother hosted musical evenings featuring mostly Mozart. She played piano, while Einstein played violin. “He was very patient with my shortcomings,” she recalled. “At the worst he used to say, ‘There you are, stuck like the donkey on the mountain,’ and he would point with his bow to the place where I had to come in.”

What Einstein appreciated in Mozart and Bach was the clear architectural structure that made their music seem “deterministic” and, like his own favorite scientific theories, plucked from the universe rather than composed. “Beethoven created his music,” Einstein once said, but “Mozart’s music is so pure it seems to have been ever-present in the universe.” He contrasted Beethoven with Bach: “I feel uncomfortable listening to Beethoven. I think he is too personal, almost naked. Give me Bach, rather, and then more Bach.”

He also admired Schubert for his “superlative ability to express emotion.” But in a questionnaire he once filled out, he was critical about other composers in ways that reflect some of his scientific sentiments: Handel had “a certain shallowness”; Mendelssohn displayed “considerable talent but an indefinable lack of depth that often leads to banality”; Wagner had a “lack of architectural structure I see as decadence”; and Strauss was “gifted but without inner truth.”¹⁷

Einstein also took up sailing, a more solitary pursuit, in the glorious Alpine lakes around Zurich. “I still remember how when the breeze dropped and the sails drooped like withered leaves, he would take out his small notebook and he would start scribbling,” recalled Suzanne Markwalder. “But as soon as there was a breath of wind he was immediately ready to start sailing again.”¹⁸

The political sentiments he had felt as a boy—a contempt for arbitrary authority, an aversion to militarism and nationalism, a respect for individuality, a disdain for bourgeois consumption or ostentatious wealth, and a desire for social equality—had been encouraged by his landlord and surrogate father in Aarau, Jost Winteler. Now, in Zurich, he met a friend of Winteler’s who became a similar political mentor: Gustav Maier, a Jewish banker who had helped arrange Einstein’s first visit to the Polytechnic. With support from Winteler, Maier founded the Swiss branch of the Society for Ethical Culture, and Einstein was a frequent guest at their informal gatherings in Maier’s home.

Einstein also came to know and like Friedrich Adler, the son of Austria’s Social Democratic leader, who was studying in Zurich. Einstein later called him the “purest and most fervent idealist” he had ever met. Adler tried to get Einstein to join the Social Democrats. But it was not Einstein’s style to spend time at meetings of organized institutions.¹⁹

His distracted demeanor, casual grooming, frayed clothing, and forgetfulness, which were later to make him appear to be the iconic absentminded professor, were already evident in his student days. He was known to leave behind clothes, and sometimes even his suitcase, when he traveled, and his inability to remember his keys became a running joke with his landlady. He once visited the home of family friends and, he recalled, “I left forgetting my suitcase. My host said to my parents, ‘That man will never amount to anything because he can’t remember anything.’ ”²⁰

This carefree life as a student was clouded by the continued financial failings of his father, who, against Einstein’s advice, kept trying to set up his own businesses rather than go to work for a salary at a stable company, as Uncle Jakob had finally done. “If I had my way, papa would have looked for salaried employment two years ago,” he wrote his sister during a particularly gloomy moment in 1898 when his father’s business seemed doomed to fail again.

The letter was unusually despairing, probably more than his parents’ financial situation actually warranted:

Perhaps this was all merely an attack of teenage angst. In any event, his father seemed to get through the crisis with his usual optimism. By the following February, he had won contracts for providing street lights to two small villages near Milan. “I am happy at the thought that the worst worries are over for our parents,” Einstein wrote Maja. “If everyone lived such a way, namely like me, the writing of novels would never have been invented.”²²

Einstein’s new bohemian life and old self-absorbed nature made it unlikely that he would continue his relationship with Marie Winteler, the sweet and somewhat flighty daughter of the family he had boarded with in Aarau. At first, he still sent her, via the mail, baskets of his laundry, which she would wash and then return. Sometimes there was not even a note attached, but she would cheerfully try to please him. In one letter she wrote of “crossing the woods in the pouring rain” to the post office to send back his clean clothes. “In vain did I strain my eyes for a little note, but the mere sight of your dear handwriting in the address was enough to make me happy.”

When Einstein sent word that he planned to visit her, Marie was giddy. “I really thank you, Albert, for wanting to come to Aarau, and I don’t have to tell you that I will be counting the minutes until that time,” she wrote.“I could never describe, because there are no words for it, how blissful I feel ever since the dear soul of yours has come to live and weave in my soul. I love you for all eternity, sweetheart.”

But he wanted to break off the relationship. In one of his first letters after arriving at the Zurich Polytechnic, he suggested that they refrain from writing each other. “My love, I do not quite understand a passage in your letter,” she replied. “You write that you do not want to correspond with me any longer, but why not, sweetheart? ... You must be quite annoyed with me if you can write so rudely.” Then she tried to laugh off the problem: “But wait, you’ll get some proper scolding when I get home.”²³

Einstein’s next letter was even less friendly, and he complained about a teapot she had given him. “The matter of my sending you the stupid little teapot does not have to please you at all as long as you are going to brew some good tea in it,” she replied. “Stop making that angry face which looked at me from all the sides and corners of the writing paper.” There was a little boy in the school where she taught named Albert, she said, who looked like him. “I love him ever so much,” she said. “Something comes over me when he looks at me and I always believe that you are looking at your little sweetheart.”²⁴

But then the letters from Einstein stopped, despite Marie’s pleas. She even wrote his mother for advice. “The rascal has become frightfully lazy,” Pauline Einstein replied. “I have been waiting in vain for news for these last three days; I will have to give him a thorough talking-to once he’s here.”²⁵

Finally, Einstein declared the relationship over in a letter to Marie’s mother, saying that he would not come to Aarau during his academic break that spring. “It would be more than unworthy of me to buy a few days of bliss at the cost of new pain, of which I have already caused too much to the dear child through my fault,” he wrote.

He went on to give a remarkably introspective—and memorable—assessment of how he had begun to avoid the pain of emotional commitments and the distractions of what he called the “merely personal” by retreating into science:

Einstein’s coolness toward Marie Winteler can seem, from our vantage, cruel. Yet relationships, especially those of teenagers, are hard to judge from afar. They were very different from each other, particularly intellectually. Marie’s letters, especially when she was feeling insecure, often descended into babble. “I’m writing a lot of rubbish, isn’t that so, and in the end you’ll not even read it to the finish (but I don’t believe that),” she wrote in one. In another, she said, “I do not think about myself, sweetheart, that’s quite true, but the only reason for this is that I do not think at all, except when it comes to some tremendously stupid calculation that requires, for a change, that I know more than my pupils.”²⁷

Whoever was to blame, if either, it was not surprising that they ended up on different paths. After her relationship with Einstein ended, Marie lapsed into a nervous depression, often missing days of teaching, and a few years later married the manager of a watch factory. Einstein, on the other hand, rebounded from the relationship by falling into the arms of someone who was just about as different from Marie as could be imagined.

Mileva Mari was the first and favorite child of an ambitious Serbian peasant who had joined the army, married into modest wealth, and then dedicated himself to making sure that his brilliant daughter was able to prevail in the male world of math and physics. She spent most of her childhood in Novi Sad, a Serbian city then held by Hungary,²⁸ and attended a variety of ever more demanding schools, at each of which she was at the top of her class, culminating when her father convinced the all-male Classical Gymnasium in Zagreb to let her enroll. After graduating there with the top grades in physics and math, she made her way to Zurich, where she became, just before she turned 21, the only woman in Einstein’s section of the Polytechnic.

More than three years older than Einstein, afflicted with a congenital hip dislocation that caused her to limp, and prone to bouts of tuberculosis and despondency, Mileva Mari was known for neither her looks nor her personality. “Very smart and serious, small, delicate, brunette, ugly,” is how one of her female friends in Zurich described her.

But she had qualities that Einstein, at least during his romantic scholar years, found attractive: a passion for math and science, a brooding depth, and a beguiling soul. Her deep-set eyes had a haunting intensity, her face an enticing touch of melancholy.²⁹ She would become, over time, Einstein’s muse, partner, lover, wife, bête noire, and antagonist, and she would create an emotional field more powerful than that of anyone else in his life. It would alternately attract and repulse him with a force so strong that a mere scientist like himself would never be able to fathom it.

They met when they both entered the Polytechnic in October 1896, but their relationship took a while to develop. There is no sign, from their letters or recollections, that they were anything more than classmates that first academic year. They did, however, decide to go hiking together in the summer of 1897. That fall, “frightened by the new feelings she was experiencing” because of Einstein, Mari decided to leave the Polytechnic temporarily and instead audit classes at Heidelberg University.³⁰

Her first surviving letter to Einstein, written a few weeks after she moved to Heidelberg, shows glimmers of a romantic attraction but also highlights her self-confident nonchalance. She addresses Einstein with the formal Sie in German, rather than the more intimate du. Unlike Marie Winteler, she teasingly makes the point that she has not been obsessing about him, even though he had written an unusually long letter to her. “It’s now been quite a while since I received your letter,” she said, “and I would have replied immediately and thanked you for the sacrifice of writing four long pages, would have also told of the joy you provided me through our trip together, but you said I should write to you someday when I happened to be bored. And I am very obedient, and I waited and waited for boredom to set in; but so far my waiting has been in vain.”

Distinguishing Mari even more from Marie Winteler was the intellectual intensity of her letters. In this first one, she enthused over the lectures she had been attending of Philipp Lenard, then an assistant professor at Heidelberg, on kinetic theory, which explains the properties of gases as being due to the actions of millions of individual molecules. “Oh, it was really neat at the lecture of Professor Lenard yesterday,” she wrote. “He is talking now about the kinetic theory of heat and gases. So, it turns out that the molecules of oxygen move with a velocity of over 400 meters per second, then the good professor calculated and calculated . . . and it finally turned out even though molecules do move with this velocity, they travel a distance of only 1/100 of a hairbreadth.”

Kinetic theory had not yet been fully accepted by the scientific establishment (nor, for that matter, had even the existence of atoms and molecules), and Mari’s letter indicated that she did not have a deep understanding of the subject. In addition, there was a sad irony: Lenard would be one of Einstein’s early inspirations but later one of his most hateful anti-Semitic tormentors.

Mari also commented on ideas Einstein had shared in his earlier letter about the difficulty mortals have in comprehending the infinite. “I do not believe that the structure of the human brain is to be blamed for the fact that man cannot grasp infinity,” she wrote. “Man is very capable of imagining infinite happiness, and he should be able to grasp the infinity of space—I think that should be much easier.” There is a slight echo of Einstein’s escape from the “merely personal” into the safety of scientific thinking: finding it easier to imagine infinite space than infinite happiness.

Yet Mari was also, it is clear from her letter, thinking of Einstein in a more personal way. She had even talked to her adoring and protective father about him. “Papa gave me some tobacco to take with me and I was supposed to hand it to you personally,” she said. “He wanted so much to whet your appetite for our little land of outlaws. I told him all about you—you must absolutely come back with me someday. The two of you would really have a lot to talk about!” The tobacco, unlike Marie Winteler’s teapot, was a present Einstein would likely have wanted, but Mari teased that she wasn’t sending it.“You would have to pay duty on it, and then you would curse me.”³¹

That conflicting admixture of playfulness and seriousness, of insouciance and intensity, of intimacy and detachment—so peculiar yet also so evident in Einstein as well—must have appealed to him. He urged her to return to Zurich. By February 1898, she had made up her mind to do so, and he was thrilled. “I’m sure you won’t regret your decision,” he wrote. “You should come back as soon as possible.”

He gave her a thumbnail of how each of the professors was performing (admitting that he found the one teaching geometry to be “a little impenetrable”), and he promised to help her catch up with the aid of the lecture notes he and Marcel Grossmann had kept. The one problem was that she would probably not be able to get her “old pleasant room” at the nearby pension back. “Serves you right, you little runaway!”³²

By April she was back, in a boarding house a few blocks from his, and now they were a couple. They shared books, intellectual enthusiasms, intimacies, and access to each other’s apartments. One day, when he again forgot his key and found himself locked out of his own place, he went to hers and borrowed her copy of a physics text. “Don’t be angry with me,” he said in the little note he left her. Later that year, a similar note left for her added, “If you don’t mind, I’d like to come over this evening to read with you.”³³

Friends were surprised that a sensuous and handsome man such as Einstein, who could have almost any woman fall for him, would find himself with a short and plain Serbian who had a limp and exuded an air of melancholy. “I would never be brave enough to marry a woman unless she were absolutely healthy,” a fellow student said to him. Einstein replied, “But she has such a lovely voice.”³⁴

Einstein’s mother, who had adored Marie Winteler, was similarly dubious about the dark intellectual who had replaced her. “Your photograph had quite an effect on my old lady,” Einstein wrote from Milan, where he was visiting his parents during spring break of 1899. “While she studied it carefully, I said with the deepest sympathy: ‘Yes, yes, she certainly is a clever one.’ I’ve already had to endure much teasing about this.”³⁵

It is easy to see why Einstein felt such an affinity for Mari. They were kindred spirits who perceived themselves as aloof scholars and outsiders. Slightly rebellious toward bourgeois expectations, they were both intellectuals who sought as a lover someone who would also be a partner, colleague, and collaborator. “We understand each other’s dark souls so well, and also drinking coffee and eating sausages, etcetera,” Einstein wrote her.

He had a way of making the etcetera sound roguish. He closed another letter: “Best wishes etc., especially the latter.” After being apart for a few weeks, he listed the things he liked to do with her: “Soon I’ll be with my sweetheart again and can kiss her, hug her, make coffee with her, scold her, study with her, laugh with her, walk with her, chat with her, and ad infinitum!” They took pride in sharing a quirkiness. “I’m the same old rogue as I’ve always been,” he wrote, “full of whims and mischief, and as moody as ever!”³⁶

Above all, Einstein loved Mari for her mind. “How proud I will be to have a little Ph.D. for a sweetheart,” he wrote to her at one point. Science and romance seemed to be interwoven. While on vacation with his family in 1899, Einstein lamented in a letter to Mari, “When I read Helmholtz for the first time I could not—and still cannot—believe that I was doing so without you sitting next to me. I enjoy working together and I find it soothing and also less boring.”

Indeed, most of their letters mixed romantic effusions with scientific enthusiasms, often with an emphasis on the latter. In one letter, for example, he foreshadowed not only the title but also some of the concepts of his great paper on special relativity. “I am more and more convinced that the electrodynamics of moving bodies as it is presented today does not correspond to reality and that it will be possible to present it in a simpler way,” he wrote. “The introduction of the term ‘ether’ into theories of electricity has led to the conception of a medium whose motion can be described without, I believe, being able to ascribe physical meaning to it.”³⁷

Even though this mix of intellectual and emotional companionship appealed to him, every now and then he recalled the enticement of the simpler desire represented by Marie Winteler. And with the tactlessness that masqueraded for him as honesty (or perhaps because of his puckish desire to torment), he let Mari know it. After his 1899 summer vacation, he decided to take his sister to enroll in school in Aarau, where Marie lived. He wrote Mari to assure her that he would not spend much time with his former girlfriend, but the pledge was written in a way that was, perhaps intentionally, more unsettling than reassuring. “I won’t be going to Aarau as often now that the daughter I was so madly in love with four years ago is coming back home,” he said. “For the most part I feel quite secure in my high fortress of calm. But I know that if I saw her a few more times, I would certainly go mad. Of that I am certain, and I fear it like fire.”

But the letter goes on, happily for Mari, with a description of what they would do when they met back in Zurich, a passage in which Einstein showed once again why their relationship was so special. “The first thing we’ll do is climb the Ütliberg,” he said, referring to a high point just out of town. There they would be able to “take pleasure in unpacking our memories” of the things they had done together on other hiking trips. “I can already imagine the fun we will have,” he wrote. Finally, with a flourish only they could have fully appreciated, he concluded, “And then we’ll start in on Helmholtz’s electromagnetic theory of light.”³⁸

In the ensuing months, their letters became even more intimate and passionate. He began calling her Doxerl (Dollie), as well as “my wild little rascal” and “my street urchin”; she called him Johannzel (Johnnie) and “my wicked little sweetheart.” By the start of 1900, they were using the familiar du with one another, a process that began with a little note from her that reads, in full:

A thousand kisses from your Dollie³⁹

Academically, things were also going well for Einstein. In his intermediate exams in October 1898, he had finished first in his class, with an average of 5.7 out of a possible 6. Finishing second, with a 5.6, was his friend and math note-taker Marcel Grossmann.⁴⁰

To graduate, Einstein had to do a research thesis. He initially proposed to Professor Weber that he do an experiment to measure how fast the earth was moving through the ether, the supposed substance that allowed light waves to propagate through space. The accepted wisdom, which he would famously destroy with his special theory of relativity, was that if the earth were moving through this ether toward or away from the source of a light beam, we’d be able to detect a difference in the observed speed of the light.

During his visit to Aarau at the end of his summer vacation of 1899, he worked on this issue with the rector of his old school there. “I had a good idea for investigating the way in which a body’s relative motion with respect to the ether affects the velocity of the propagation of light,” he wrote Mari. His idea involved building an apparatus that would use angled mirrors “so that light from a single source would be reflected in two different directions,” sending one part of the beam in the direction of the earth’s movement and the other part of the beam perpendicular to it. In a lecture on how he discovered relativity, Einstein recalled that his idea was to split a light beam, reflect it in different directions, and see if there was “a difference in energy depending on whether or not the direction was along the earth’s motion through the ether.” This could be done, he posited, by “using two thermoelectric piles to examine the difference of the heat generated in them.”⁴¹

Weber rejected the proposal. What Einstein did not fully realize was that similar experiments had already been done by many others, including the Americans Albert Michelson and Edward Morley, and none had been able to detect any evidence of the perplexing ether—or that the speed of light varied depending on the motion of the observer or the light source. After discussing the topic with Weber, Einstein read a paper delivered the previous year by Wilhelm Wien, which briefly described thirteen experiments that had been conducted to detect the ether, including the Michelson-Morley one.

Einstein sent Professor Wien his own speculative paper on that topic and asked him to write him back. “He’ll write me via the Polytechnic,” Einstein predicted to Mari. “If you see a letter there for me, you may go ahead and open it.” There is no evidence that Wien ever wrote back.⁴²

Einstein’s next research proposal involved exploring the link between the ability of different materials to conduct heat and to conduct electricity, something that was suggested by the electron theory. Weber apparently did not like that idea either, so Einstein was reduced, along with Mari, to doing a study purely on heat conduction, which was one of Weber’s specialties.

Einstein later dismissed their graduation research papers as being of “no interest to me.” Weber gave Einstein and Mari the two lowest essay grades in the class, a 4.5 and a 4.0, respectively; Grossmann, by comparison, got a 5.5. Adding annoyance to that injury, Weber said that Einstein had not written his on the proper regulation paper, and he forced him to copy the entire essay over again.⁴³

Despite the low mark on his essay, Einstein was able to eke by with a 4.9 average in his final set of grades, placing him fourth in his class of five. Although history refutes the delicious myth that he flunked math in high school, at least it does offer as a consolation the amusement that he graduated college near the bottom of his class.

At least he graduated. His 4.9 average was just enough to let him get his diploma, which he did officially in July 1900. Mileva Mari, however, managed only a 4.0, by far the lowest in the class, and was not allowed to graduate. She determined that she would try again the following year.⁴⁴

Not surprisingly, Einstein’s years at the Polytechnic were marked by his pride at casting himself as a nonconformist. “His spirit of independence asserted itself one day in class when the professor mentioned a mild disciplinary measure just taken by the school’s authorities,” a classmate recalled. Einstein protested. The fundamental requirement of education, he felt, was the “need for intellectual freedom.”⁴⁵

Throughout his life, Einstein would speak lovingly of the Zurich Polytechnic, but he also would note that he did not like the discipline that was inherent in the system of examinations. “The hitch in this was, of course, that one had to cram all this stuff into one’s mind for the examinations, whether one liked it or not,” he said. “This coercion had such a deterring effect that, after I had passed the final examination, I found the consideration of any scientific problems distasteful to me for an entire year.”⁴⁶

In reality, that was neither possible nor true. He was cured within weeks, and he ended up taking with him some science books, including texts by Gustav Kirchhoff and Ludwig Boltzmann, when he joined his mother and sister later that July for their summer holiday in the Swiss Alps. “I’ve been studying a great deal,” he wrote Mari, “mainly Kirch-hoff ’s notorious investigations of the motion of the rigid body.” He admitted that his resentment over the exams had already worn off. “My nerves have calmed down enough so that I’m able to work happily again,” he said. “How are yours?”⁴⁷