by Michio Kaku
But Einstein was determined to see Mileva, even if it meant causing a deep rupture in his close-knit family. Once, when Einstein’s mother was visiting her son, she asked, “What’s to become of her?” When Einstein replied, “My wife,” she suddenly threw herself on the bed, sobbing uncontrollably. His mother accused him of destroying his future for a woman “who cannot gain entrance to a good family.” Eventually, facing the fierce opposition from his parents, Einstein would have to shelve any thoughts of marriage to Mileva until he finished school and got a well-paying job.
In 1900, when Einstein finally graduated from the Polytechnic with a degree in physics and mathematics, his luck soured. It was assumed that he would be given an assistantship. This was the norm, especially since he had passed all his exams and had done well in school. But because Professor Weber had withdrawn his job offer, Einstein was the only one in his class denied an assistantship—a deliberate slap in the face. Once so cocky, he suddenly found himself in uncertain circumstances, especially as financial support from a well-to-do aunt in Genoa dried up with his graduation.
Unaware of the depth of Weber’s intense antipathy, Einstein foolishly gave Weber’s name as a reference, not realizing that this would further sabotage his future. Reluctantly, he began to realize that this error probably doomed his career even before it started. He would lament bitterly, “I would have found [a job] long ago if Weber had not played a dishonest game with me. All the same, I leave no stone unturned and do not give up my sense of humor…. God created the donkey and gave him a thick hide.”
Meanwhile, Einstein also applied for Swiss citizenship, but this was impossible until he could prove he was employed. His world was collapsing swiftly. The thought of having to play the violin on the street like a beggar crossed his mind.
His father, realizing his son’s desperate plight, wrote a letter to Professor Wilhelm Ostwald of Leipzig, pleading with him to give his son an assistantship. (Ostwald never even responded to this letter. Ironically, a decade later Ostwald would be the first person to nominate Einstein for the Nobel Prize in physics.) Einstein would note how unfair the world suddenly became: “By the mere existence of his stomach, everyone was condemned to participate in that chase.” He wrote sadly, “I am nothing but a burden to my relatives…. It would surely be better if I did not live at all.”
To make matters worse, just at this time his father’s business once again went bankrupt. In fact, his father spent all of his wife’s inheritance and was deeply in debt to her family. Lacking any financial support, Einstein had no choice but to find the most menial teaching position available. Desperate, he began to comb the newspapers for any hint of a job. At one point, he almost gave up hope of ever becoming a physicist and seriously considered working for an insurance company.
In 1901, he found a job teaching mathematics at the Winterthur Technical School. Somehow, between exhausting teaching duties, he was able to squeeze enough time to write his first published paper, “Deductions from the Phenomena of Capillarity,” which Einstein himself realized was not earthshaking. The next year, he took a temporary tutoring position at a boarding school in Schaffhausen. True to form, he could not get along with the authoritarian director of the school, Jakob Nuesch, and was summarily fired. (The director was so inflamed that he even accused Einstein of fomenting a revolution.)
Einstein was beginning to think that he would spend the rest of his life forced to eke out a menial existence tutoring indifferent students and scouring the ads in newspapers. His friend Friedrich Adler would recall that at this time Albert was close to starvation. He was a complete failure. Still he refused to ask his relatives for a handout. Then he faced two more setbacks. First, Mileva flunked her final exams at the Polytechnic for the second time. This meant that her career as a physicist was essentially finished. No one would ever accept her into a graduate program with her dismal record. Painfully disheartened, she lost interest in physics. Their romantic dreams of exploring the universe together were over. And then, in November 1901, when Mileva was back home, he received a letter from her telling him that she was pregnant!
Einstein, despite his lack of prospects, was still thrilled at the possibility of becoming a father. Being separated from Mileva was torture, but they furiously exchanged letters, almost daily. On February 4, 1902, he finally learned he was a father of a baby girl, born at Mileva’s parents’ home in Novi Sad and christened Lieserl. Excited, Einstein wanted to know everything about her. He even pleaded with Mileva to please send a photo or a sketch of her. Mysteriously, no one is sure what happened to the child. The last mention of her is in a letter from September 1903, which stated that she was suffering from scarlet fever. Historians believe that she most likely died of the disease or that she was eventually given up for adoption.
Just when his fortunes appeared as if they could not sink any lower, Einstein received word from an unexpected source. His good friend Marcel Grossman had been able to secure a job for him as a minor civil servant at the Bern Patent Office. From that lowly position, Einstein would change the world. (To keep alive his fading hopes of one day becoming a professor, he persuaded Professor Alfred Kleiner of the University of Zurich to be his Ph.D. advisor during this period.)
On June 23, 1902, Einstein began work at the patent office as a technical expert, third class, with a paltry salary. In hindsight, there were at least three hidden advantages to working at this office. First, his job forced him to find the basic physical principles that underlay any invention. During the day, he honed his considerable physical instincts by stripping away unnecessary details and isolating the essential ingredient of each patent and then writing up a report. His reports were so long on detail and analysis that he wrote to his friends that he was making a living “pissing ink.” Second, many of the patent applications concerned electromechanical devices, so his ample experience visualizing the inner workings of dynamos and electric motors from his father’s factory was a great help. And last, it freed him from distractions and gave him time to ponder deep questions about light and motion. Often, he could finish the details of his work quickly, leaving hours to fall back on the daydreams that dogged him since his youth. In his work and especially at night, he returned to his physics. The quiet atmosphere of the patent office suited him. He called it his “worldly monastery.”
Einstein had barely settled into his new job at the patent office when he learned that his father was dying of heart disease. In October he had to depart immediately for Milan. On his deathbed, Hermann finally gave Albert his blessing to marry Mileva. The death left Albert with an overpowering sense that he had disappointed his father and family, a feeling that would stay with him forever. His secretary, Helen Dukas, wrote, “Many years later, he still recalled vividly his shattering sense of loss. Indeed on one occasion he wrote that his father’s death was the deepest shock he had ever experienced.” Maja, in particular, bitterly noted that “sad fate did not permit [her father] even to suspect that two years later his son would lay the foundation of his future greatness and fame.”
In January of 1903, Einstein finally felt secure enough to marry Mileva. A year later, their son Hans was born. Einstein settled down to the life of a lowly civil servant in Bern, a husband, and a father. His friend David Reichinstein vividly remembered visiting Einstein during this period: “The door of the flat was open to allow the floor, which had just been scrubbed, and the washing, hung up in the hall, to dry. I entered Einstein’s room. With one hand, he was stoically rocking a bassinet in which there was a child. In his mouth, Einstein had a bad, a very bad cigar, and in the other hand, an open book. The stove was smoking horribly.”
To raise some extra money, he put an ad in the local newspaper, offering “private lessons in mathematics and physics.” It was the first recorded mention of Einstein’s name in any newspaper. Maurice Solovine, a Jewish Romanian student of philosophy, was the first student to answer the ad. To his delight, Einstein found that Solovine was an excellent sounding board for h
is many ideas about space, time, and light. To prevent himself from becoming dangerously isolated from the main currents in physics, he hit upon the idea of forming an informal study group, which Einstein mockingly called the “Olympian Academy,” to debate the great issues of the day.
In hindsight, the days spent with the academy group were perhaps the most joyous in Einstein’s life. Decades later, tears would come to his eyes when he recalled the vibrant, audacious claims they made as they voraciously devoured all the major scientific works of the day. Their spirited debates and raucous discussions filled the coffeehouses and beer halls of Zurich, and anything seemed possible. They would fondly swear, “These words of Epicurus applied to us: ‘What a beautiful thing joyous poverty is!’”
In particular, they poured over the controversial work of Ernst Mach, a Viennese physicist and philosopher who was something of a gadfly, challenging any physicist who spoke of things that were beyond our senses. Mach spelled out his theories in an influential book, The Science of Mechanics. He challenged the idea of atoms, which he thought were hopelessly beyond the realm of measurement. What most riveted Einstein’s attention, however, was Mach’s scathing criticism of the aether and absolute motion. To Mach, the imposing edifice of Newtonian mechanics was based on sand, as the concepts of absolute space and absolute time could never be measured. He believed relative motions could be measured, but absolute motions could not. No one had ever found the mystical absolute reference frame that could determine the motion of the planets and the stars, and no one had ever found even the slightest experimental evidence for the aether either.
One series of experiments that indicated a fatal weakness in this Newtonian picture had been performed in 1887 by Albert Michelson and Edward Morley, who had set out to give the best possible measurement of the properties of this invisible aether. They reasoned that the earth moves within this sea of aether, creating an “aether wind,” and hence the speed of light should change, depending on the direction the earth took.
Think, for example, of running with the wind. If you run in the same direction as the wind, then you feel yourself being pushed along with the wind. With the wind at your back, you travel at a faster speed, and in fact your speed has been increased by the speed of the wind. If you run into the wind, then you slow down; your speed is now decreased by the speed of the wind. Similarly if you run sideways, 90 degrees to the wind, you are blown off to the side with yet another speed. The point is that your speed changes depending on which direction you run with respect to the wind.
Michelson and Morley devised a clever experiment whereby a single beam of light is split into two distinct beams, each shot in different directions at right angles to each other. Mirrors reflected the beams back to the source, and then the two beams were allowed to mix and interfere with each other. The whole apparatus was carefully placed on a bed of liquid mercury, so that it could rotate freely, and it was so delicate that it easily picked up the motion of passing horse carriages. According to the aether theory, the two beams should travel at different speeds. One beam, for example, would move along the direction of the earth’s motion in the aether, and the other beam would move at 90 degrees to the aether wind. Thus, when they returned back to the source, they should be out of phase with each other.
Much to their astonishment, Michelson and Morley found that the speed of light was identical for all light beams, no matter in which direction the apparatus pointed. This was deeply disturbing, for it meant that there was no aether wind at all, and the speed of light never changed, even as they rotated their apparatus in all directions.
This left physicists with two equally unpleasant choices. One was that the earth might be perfectly stationary with respect to the aether. This choice seemed to violate everything known about astronomy since the original work of Copernicus, who found that there was nothing special about the location of the earth in the universe. Second, one might abandon the aether theory and Newtonian mechanics along with it.
Heroic efforts were made to salvage the aether theory. The closest step toward a resolution to this puzzle was found by the Dutch physicist Hendrik Lorentz and the Irish physicist George FitzGerald. They reasoned that the earth, in its motion through the aether, was actually physically compressed by the aether wind, so that all meter sticks in the Michelson-Morley experiment were shrunken. The aether, which already had near mystical properties of being invisible, noncompressible, extremely dense, and so on, now had one more property: it could mechanically compress atoms by passing through them. This would conveniently explain the negative result. In this picture, the speed of light did in fact change, but you could never measure it because every time you tried using a meter stick, the velocity of light would indeed change and the meter sticks would shrink in the direction of the aether wind by precisely the right amount.
Lorentz and FitzGerald independently calculated the amount of shrinkage, yielding what is now called the “Lorentz-FitzGerald contraction.” Neither Lorentz nor FitzGerald were especially pleased with this result; it was simply a quick fix, a way of patching up Newtonian mechanics, but it was the best they could do. Not many physicists liked the Lorentz-FitzGerald contraction either, since it smacked of being an ad hoc principle, thrown in to prop up the sagging fortunes of the aether theory. To Einstein, the idea of the aether, with its near miraculous properties, seemed artificial and contrived. Earlier, Copernicus had destroyed the earth-centered solar system of Ptolemy, which required the planets to move in extremely complex circular motions called “epicycles.” With Occam’s Razor, Copernicus sliced away the blizzard of epicycles needed to patch up the Ptolemaic system and put the sun at the center of the solar system.
Like Copernicus, Einstein would use Occam’s Razor to slice away the many pretensions of the aether theory. And he would do this by using a children’s picture.
CHAPTER 3
Special Relativity and the “Miracle Year”
Intrigued by Mach’s criticisms of Newton’s theory, Einstein went back to the picture that had haunted him since he was sixteen, running alongside a light beam. He returned to the curious but important discovery that he made while at the Polytechnic, that in Maxwell’s theory the speed of light was the same, no matter how you measured it. For years, he puzzled over how this could possibly happen, because in a Newtonian, commonsense world you can always catch up to a speeding object.
Imagine again the police officer chasing after a speeding motorist. If he drives fast enough, the officer knows that he can catch up to the motorist. Anyone who has ever gotten a ticket for speeding knows that. But if we now replace the speeding motorist with a light beam, and an observer witnesses the whole thing, then the observer concludes that the officer is speeding just behind the light beam, traveling almost as fast as light. We are confident that the officer knows he is traveling neck and neck with the light beam. But later, when we interview him, we hear a strange tale. He claims that instead of riding alongside the light beam as we just witnessed, it sped away from him, leaving him in the dust. He says that no matter how much he gunned his engines, the light beam sped away at precisely the same velocity. In fact, he swears that he could not even make a dent in catching up to the light beam. No matter how fast he traveled, the light beam traveled away from him at the speed of light, as if he were stationary instead of speeding in a police car.
But when you insist that you saw the police officer speeding neck and neck with the light beam, within a hairsbreadth of catching up to it, he says you are crazy; he never even got close. To Einstein, this was the central, nagging mystery: How was it possible for two people to see the same event in such totally different ways? If the speed of light was really a constant of nature, then how could a witness claim that the officer was neck and neck with the light beam, yet the officer swears that he never even got close?
Einstein had realized earlier that the Newtonian picture (where velocities can be added and subtracted) and the Maxwellian picture (where the speed of light was a constan
t) were in total contradiction. Newtonian theory was a self-contained system, resting on a few assumptions. If only one of these assumptions were changed, it would unravel the entire theory in the same way that a loose thread can unravel a sweater. That thread would be Einstein’s daydream of racing a light beam.
One day around May of 1905, Einstein went to visit his good friend Michele Besso, who also worked at the patent office, and laid out the dimensions of the problem that had puzzled him for a decade. Using Besso as his favorite sounding board for ideas, Einstein presented the issue: Newtonian mechanics and Maxwell’s equations, the two pillars of physics, were incompatible. One or the other was wrong. Whichever theory proved to be correct, the final resolution would require a vast reorganization of all of physics. He went over and over the paradox of racing a light beam. Einstein would later recall, “The germ of the special relativity theory was already present in that paradox.” They talked for hours, discussing every aspect of the problem, including Newton’s concept of absolute space and time, which seemed to violate Maxwell’s constancy of the speed of light. Eventually, totally exhausted, Einstein announced that he was defeated and would give up the entire quest. It was no use; he had failed.
Although Einstein was depressed, his thoughts were still churning in his mind when he returned home that night. In particular, he remembered riding in a street car in Bern and looking back at the famous clock tower that dominated the city. He then imagined what would happen if his street car raced away from the clock tower at the speed of light. He quickly realized that the clock would appear stopped, since light could not catch up to the street car, but his own clock in the street car would beat normally.