True Genius: The Life and Science of John Bardeen: The Only Winner of Two Nobel Prizes in Physics (2002)

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10 Homecoming T he grand sweep of the prairie came as an unexpected thrill to Jane when the family drove into Champaign-Urbana in June 1951. She “gasped because it was so glorious.” She had had misgivings about the move, especially after John’s visit to Urbana the previous spring when he had brought home dire warnings from faculty wives who hated the endless fields upon fields of corn and soybeans that grew there on some of the nation’s richest farmland. Many found the Midwest a cultural void. Jane, however, loved the sense of space and freedom evoked by the central plains and the region’s wide skies, at times dramatically animated by electrical storms. She appreciated the white farm- houses that decorated the verdant landscape and the wildlife of the region. Here and there a section of wooded river valley had been set aside as a park or greenway. Along roadsides and railroad rights of way, tall grasses provided cover for a variety of wild animals. In the cool air of dawn and dusk, deer, raccoons, foxes, and pheasants quietly explored the fields. Falcons rested alertly on telephone lines, waiting for a meal, while redwinged blackbirds whistled shrilly from fence posts. John experienced moving to Illinois like coming home. He was immediately comfortable in the small twin cities of Urbana and Champaign. In some ways the atmosphere resembled the Madison of his youth. 165 

166 TRUE GENIUS The two Illinois cities dated back to when the Illinois Central Railroad came through the region in 1854. The tracks ran two miles west of the Urbana border. A small community sprang up around the railroad depot, and its residents resisted when Urbana tried to annex the area in 1855. Five years later the new depot town was incorporated as Champaign. With the railroad providing transpor- tation to Chicago, Champaign became the county’s commercial center, much to the chagrin of Urbana residents. Both towns grew rapidly with subdivisions replacing soybeans at a breakneck pace, especially in Champaign. Soon the towns bumped up against one another, until all that divided them was their separate systems of governance. The university, straddling Wright Street, the border be- tween the two towns, became a center of activity and growth. The Bardeens had purchased a large, pie-shaped lot at 55 Greencroft, in a new subdivision on the western edge of Champaign. The modest ranch-style house, already under construction there, would meet their needs for the next forty years. It was near the university, but not close enough to be disturbed by campus bustle. As the neighborhood aged, the vast fields of corn and soybeans that had once stretched from Greencroft into the distance were gradu- ally replaced by new developments, but Champaign held on to its small-town atmosphere. That suited the Bardeens just fine. “I don’t like big-city living,” John said bluntly. The new house would offer something for every member of the family. Jane and John’s large bedroom overlooked the backyard. The boys shared a room with “Hollywood” beds, and Betsy had a room of her own. The basement made a perfect recreation room. A ping- pong table soon became its central feature. It was a room that Bardeen’s students and postdocs would come to know well. The kitchen was small but convenient. Eventually the family added a spacious sunroom to the back of the house, accessible from both the kitchen and the living room. Nearly floor-to-ceiling windows and an expansive view of trees and flowers gave the room a breezy natural feeling. Jane couldn’t wait to sink her hands into the rich black soil. That first spring she planted every kind of vegetable she could think of in her garden plot. But when the family took a two-week vacation, she returned to a tangle of overgrown plants. She learned to plant more discriminatingly and soon had a thriving garden full of flowers and vegetables. 

Homecoming 167 John’s and Jane’s different ways of appreciating the outdoors expressed their separate interests and needs. John would increas- ingly turn to golf, an activity that served as an outlet and training ground for his intense focus, competitiveness, and drive toward mastery. Jane preferred gardening—working with living, growing plants and nurturing them into their full potential. Although the two shared many things over the course of their marriage, Jane and John kept a respectful distance, allowing one another separate lives in their different spheres. The children quickly found friends in the neighborhood. Their yard, large for Champaign, was a good place for Jim and Bill to play catch with friends. John occasionally helped the boys polish their Little League baseball skills by playing catcher to their pitcher, or chasing and catching fly balls as they practiced their batting tech- niques. Bill found the neighborhood a splendid place to get into scrapes, from which he sometimes had to be rescued or even car- ried to the doctor. Once, when they were living in Summit, John had walked into the house, looked at Jane’s harried face, and asked, “What has he done now?” John had found it his unpleasant duty to occasionally administer a spanking to the accompaniment of Bill’s exaggerated screams. Once in a while John brought home books that he thought might interest the children. Many were about science. In the eve- nings he liked to play records on the family phonograph. He always claimed that “his instrument was the record player.” Mozart was a favorite, and Betsy often drifted off to sleep to the “blissful” sounds of chamber music. John liked to play with the children at their own level. “He would wrestle with us,” Betsy recalled many years later when she had children of her own. He would “toss us through the air, and let us climb all over him.” It was a favorite entertainment after dinner. “I had always thought that all parents treated their children this way,” she confessed, “until I reduced a child and her mother to hysteria when I flipped her over in one of our milder ‘tricks.’” The house on Greencroft was within walking distance of the Champaign Country Club, which at the time Bardeen joined had nearly 500 members and a new air-conditioned building. With its eighteen-hole golf course, the club provided John with countless hours of exercise and companionship. In later years the Bardeens often entertained their visitors by taking them to dinner there. 

168 TRUE GENIUS When John was off on the greens, Jane usually worked in her garden—“my golf,” she called it. Marriage and family life formed the center of Jane’s world. She took pleasure in knowing that the home she attended to was the supporting stage for John’s creative work. At the same time she continued to feel peripheral to John’s engagement with his physics. Their quietly companionable relationship resembled the one that John’s father, Charles, had shared with Althea. Jane would have preferred to have more conversation, but John was “a man of almost fewer words at home than when he was with his fellow scientists,” she once said wistfully. They sometimes squabbled. During the summer of 1956 Jane came down with a mysterious ailment during a stay in Les Houches, near Chamonix in the French Alps, where John was teaching at a summer school. John “interpreted my lack of interest in activities and my lack of enthusiasm for Les Houches as evi- dence of bad temper and a mean disposition and was very blunt in telling me so. Consequently I stubbornly resolved to keep my troubles to myself and to just stick it out until this ‘flu,’ ‘virus,’ or whatever had cured itself.” When she was finally diagnosed with typhoid, she insisted that he and the children go on with their European tour while she recovered in Switzerland. Her contrite husband sent letters and care packages from the road and offered to come stay with her. “Thanks a million for offering to come, John,” she wrote back, “but really there isn’t a thing you could do here.” When not needed by her family, and when she was not putting together dinner parties or cookouts for John’s students and col- leagues, Jane turned her energies and organizational skills outward into the community. She joined a number of local clubs, including the Score Club, a small women’s society originally organized around the musical interests of its members. By the time Jane became a member, the club had evolved into more of a reading group. She worked on problems of racial discrimination through the League of Women Voters and was active in the University Women, a university-wide organization that was “helpful to new- comers, because it gives them a door into their new community.” Even after she was no longer active in the club, Jane participated in its affairs now and then, for example, modeling the gown she wore for the 1956 Nobel ceremony and to a 1962 White House dinner. The Bardeens were not religious, but Jane believed that the 

Homecoming 169 church provided opportunities to meet people and a venue for teaching the children history, culture, and ethical standards. Soon after their move to Champaign, she “took the kids down to the First Presbyterian Church, and the next thing she knew she was teaching Sunday school.” Religious tradition, which had been an issue at the time John and Jane were married, arose again with the question of religious training for the children. Back in Summit, Jane had taken the children to a Presbyterian church. John surprised her with the com- ment that she “might have considered the Unitarians.” “Why?” she asked. “You’re not a Unitarian.” “No,” he replied, “but my father was.” It was the first time she had heard John mention a religious preference. Several years later, when Jim asked Jane whether he could quit Sunday school, because everyone there just wanted to “horse around,” Jane said yes. If he was not learning anything, he needn’t go. Bill followed suit. Betsy, however, agreed that she would go to Sunday school as long as Jane went to church. Jane became a church elder, and Betsy stayed in Sunday school. John’s mother, Althea, had been reared in the Quaker tradition, and his stepmother, Ruth, was Catholic, but John was resolutely secular throughout his life. He was once “taken by surprise” when an interviewer asked him a question about religion. “I am not a religious person,” he said, “and so do not think about it very much.” He went on in a rare elaboration of his personal beliefs. I feel that science cannot provide an answer to the ultimate ques- tions about the meaning and purpose of life. With religion, one can get answers on faith. Most scientists leave them open and perhaps unanswerable, but do abide by a code of moral values. For civilized society to succeed, there must be a common consensus on moral values and moral behavior, with due regard to the welfare of our fellow man. There are likely many sets of moral values compatible with successful civilized society. It is when they conflict that diffi- culties arise. The warm and collegial physics department welcomed Bardeen. He was free to work there on whatever subject he wanted—alone or, as he typically preferred, in collaboration with others. He could teach as much or as little as he wished and offer whatever courses he wanted to teach. The department had been built up recently into a world-class 

170 TRUE GENIUS institution by the popular and energetic F. Wheeler Loomis, who served as its head from 1929 to 1940 and again from 1947 to 1957. Loomis had been in Zürich, on leave as a Guggenheim fellow from New York University’s department of physics, when the Univer- sity of Illinois first invited him in 1929 to come as a full professor and head of the Department of Physics. Loomis was not impressed. Under Albert P. Carman, the Illinois physics department had stagnated from 1897 until 1929. It had been completely bypassed by the quantum mechanics revolution. Loomis also was not thrilled with the idea of moving from New York City to the small prairie town of Urbana. He was, however, challenged by the opportunity to transform a backward department into a world-class research institution. He learned that Roger Adams had, under similar circumstances, taken the Illinois chemistry department from rags to riches in a short time. The dean of the College of Engineering, Milo Ketchum, as- sured Loomis that he would have a free hand and generous funding to do so for physics. He took the job. (Later he learned that his name had been last on the list of possible candidates; all the others had declined.) The job proved harder than Loomis had anticipated, for shortly after his arrival the stock market crashed and the university could not deliver the promised resources. He also discovered that it was extremely difficult to attract physics “stars” to Urbana. Isadore I. Rabi had humorously rebuffed his invitation with the comment, “I love subways and I hate cows.” Loomis managed to hire a few new faculty using a successful hiring strategy similar to the one Charles Bardeen had used in shaping the Wisconsin medical school. He focused on promising postdoctoral-level scientists: “young, competent but relatively unproven people with fresh ideas, rather than less-risky, estab- lished—and more expensive—scientists.” In 1930 Loomis brought in Gerald M. Almy, a young experimental nuclear spectroscopist, later one of Loomis’s successors as head of the department. Around the same time he hired Gerald Kruger, another spectroscopist, and the nuclear physicist Donald Kerst, who would later invent the world’s first betatron, an electron accelerator for studying elemen- tary particles. Loomis hired twelve young physicists between 1937 and 1941. The median age of the department dropped from fifty- five in 1929 to thirty-two in 1940. 

Homecoming 171 Then World War II scattered most of the physicists that Loomis had brought to Illinois. He himself, along with several of his hires, landed at the MIT Radiation Laboratory, where Loomis became associate director. Almost two-thirds of the faculty that Loomis had added in the 1930s went elsewhere during the war, forcing him to undertake yet another massive rebuilding effort after his return to Illinois in 1947. This time Loomis drew on a network of influential colleagues that included his friend Louis Ridenour from the MIT Rad Labora- tory, who had received his doctorate at Caltech in the up-and- coming field of high-voltage physics (which would evolve into high-energy physics). Loomis encouraged Ridenour to accept an offer to become dean of Illinois’s graduate college. After he did, Ridenour convinced William L. Everitt, who had been an electrical engineering professor at Illinois since 1944, to become dean of the College of Engineering in 1949. Already known for numerous inventions in telephony, radio, and antenna systems, Everitt now proceeded to build one of the foremost engineering programs in the United States. For a few fertile years between 1949 and 1951, Loomis, Ridenour, and Everitt worked as a team building the Illinois School of Engineering into a world-class institution. They decided that the time was ripe to establish a strong group in solid-state physics. Ridenour was able to offer generous seed funding—including salaries for two senior and three junior positions and resources to set up a new laboratory. The administrative decisions were made easily and rapidly within the “old-boy network,” with the justify- ing paperwork typically appearing after the fact. When bargaining for resources, Loomis drew freely on his per- sonal connections with the important physicists of his day. In an era when discrimination against Jews and other minorities was common, his integrity gained him the respect of many colleagues. He was angered by the occasional “warning” about the Jewish back- ground of a job applicant. Over the years his refusal to make hiring decisions on the basis of religion or ethnicity paid off, for he was able to attract gifted candidates that other universities would not consider. Similarly, Loomis refused to be intimidated by the scare tactics of the anticommunist fanatics of the early 1950s. Edwin Goldwasser, hired by Loomis in 1951, said that he believed “Loomis made the decision [to hire me] on the grounds that I was refusing to 

172 TRUE GENIUS sign a loyalty oath.” Another physics professor had a student who belonged to the Communist Party and “the department swung behind [that professor] pretty strongly.” Ridenour’s first major solid-state hire was Fred Seitz, whom he had known in the late 1930s at the University of Pennsylvania, during the war at the MIT Rad Lab, and in the late 1940s at the Carnegie Institute of Technology where Seitz was the head of the Department of Physics. Ridenour persuaded Seitz to move to Illi- nois, with an offer that included “a lot of money by the standards of the day” and the opportunity to make several departmental appointments in solid-state physics. Despite Betty Seitz’s reservations about living in the Midwest, she “fell in love” with the area. She and Fred decided that the land- scape had “many of the qualities of the sea”: . . . the same kind of rich interplay between sky and rolling land as is seen between sky and undulating water. Brilliant sunsets and mag- nificent storms hover over the vast spread of the land. And, like the sea, the land presents markedly different aspects at different times of day and at different seasons. Seitz found the intellectual atmosphere congenial. “There were no rivalries of any significance.” He became chair of the new solid- state group. Robert Maurer and James Koehler followed Seitz from Carnegie Tech to join the solid-state group as associate professors. Four young instructors also arrived in 1949 as part of the Seitz package: David Lazarus from the University of Chicago, Dillon Mapother from Carnegie Tech, and James Schneider and Charles Slichter from Harvard. Lazarus, who was appointed at Seitz’s sug- gestion, arrived even before Seitz, who had contacted Loomis on Lazarus’s behalf after the young physicist told Seitz he was looking for a job. By the time Bardeen arrived, the Illinois physics depart- ment was, with Cornell, one of the top two academic departments in America in the area of solid-state physics. The department was also growing in other areas, including nuclear physics. In 1950 its new 300 MeV betatron went online. In 1951, through Ridenour’s energetic leadership, the University of Illinois established its commanding position in the computer revolution by designing and building two large digital computers. The first, ORDVAC, went to the Army’s Aberdeen Proving Grounds in Maryland; the second, ILLIAC (Illinois Automatic Computer), stayed in Urbana and became “one of the busiest machines on campus.” 

Homecoming 173 Morale was unusually high under Loomis. He kept each mem- ber of the department involved in its operation. He invited faculty to help determine his “Loomis list,” which ranked faculty accord- ing to the quality of their work and their overall contributions to the department. His “wonderful parties” fostered a sense of family. He encouraged a tradition (still in place today) of faculty stopping in the halls or meeting in one another’s offices or labs to chat infor- mally about physics. Around 10:00 A.M. most physicists would wander over to the departmental lounge to drink coffee while catch- ing up on the work of colleagues or discussing recent journal articles. At lunch they would meet regularly in small groups for conversation. Abundant monetary resources during the Korean War sup- ported the department’s high morale. In the 1950s much of the funding for the solid-state group came from the Office of Naval Research (ONR) or from the Atomic Energy Commission (AEC). The flow of money within the government–university circuit was eased by the personal relationships that developed among scien- tists and government officials during World War II. For example, Seitz was one of the many friends of Emmanuel Piore, chief scien- tist at the ONR, who with others (such as Mina Rees and Randal Robertson) made day-to-day funding decisions. “Everyone was Manny’s friend.” Scientists attached to well-regarded programs usually needed to write no more than a page describing a particular project to receive funding. Most modest requests (e.g., to finance a researcher and one or two graduate assistants) were funded as a matter of course. Bardeen’s new physics community extended to the entire world. After his month-long trip to Japan in 1953 to attend a meeting of the International Union of Pure and Applied Physics, he went abroad nearly every year. For that first memorable Japanese meet- ing, he and Seitz hired a military plane for the thirty-seven-hour trip. According to Seitz, Bardeen was “given very special attention, as Japan was now greatly interested in the transistor.” “I’ve never seen so many flashbulbs in my life,” John wrote Jane. He told Japa- nese scientists, “It was like ‘carrying coal to Newcastle’ to speak in a field in which you are so outstanding.” On the trip Bardeen met many Japanese scientists who would remain colleagues and friends throughout his life. Among them 

174 TRUE GENIUS was Sadao Nakajima, who presented a short paper on interactions between electrons and phonons in superconductivity. There was no time to discuss the work at the conference, so Bardeen asked Nakajima to meet him at the train station in Nagoya, where he would be stopping on his way back to Tokyo from Kyoto. “So I went to the station,” Nakajima later said, and “talked with him through the train window for a very short time while the train stopped.” Nakajima also presented Bardeen a written version of his work—in Japanese. (Bardeen had it translated back in Illinois.) Later, Nakajima accepted Bardeen’s invitation to visit Urbana. Bardeen also met Michio (George) Hatoyama, whose uncle was Japan’s premier, and Makoto Kikuchi, with whom he would have lifelong friendships. They both worked at the Japanese Ministry of International Trade and Industry’s (MITI) Electrotechnical Labora- tory (Denki Shikenjo) in Tokyo. Hatoyama entertained his Ameri- can colleague at his home during the long 1953 trip. Later, Bardeen wrote to Hatoyama that the visit to Japan had been “one of the great events of my life.” In 1960 Hatoyama left Denki Shikenjo to direct Sony’s then new research laboratory. One of his best friends, Kazuo Iwama, had been the head of the company’s transistor group since its early years. The company had been founded as Tokyo Tsushin Kogyo Company (Totsuko) in 1952, when Masaro Ibuka and his partner Akio Morita invested in patent rights for the junction transistor. They made a fortune by producing transistorized consumer products and in 1958 renamed the company Sony. Kikuchi took over as director of the Sony Research Center in 1974. Bardeen was a frequent and honored guest at Sony, and the company occasionally sent students or scientists to the University of Illinois. Bardeen often sent his Japanese colleagues letters of introduction for friends visiting Japan. He always tried to accommodate Japanese visitors to the States. Three years after Bardeen’s memorable first trip to Japan, he would write to Hatoyama and Kikuchi to introduce his student, Nick Holonyak, who had recently been drafted into the U.S. Army Signal Corps. Holonyak was to be stationed in Japan. Years later he would become the first to hold the prestigious Sony Professorship at the University of Illinois, created in honor of John Bardeen. Holonyak was a second-year graduate student in electrical en- gineering at the time he met Bardeen in the fall of 1951. Taking 

Homecoming 175 Bardeen’s undergraduate atomic physics course (Physics 381) that fall of 1951, he discovered that he “learned very effectively” from Bardeen. He rushed to sign up for Bardeen’s semiconductor course to be offered for the first time in the spring of 1952. It was among the first such courses at any university. Bardeen had begun to prepare for the course during the summer of 1951. In August he wrote to Jim Fisk to ask whether Bell Labs could supply materials: several kinds of transistors, including point- contact and junction transistors, germanium blocks and rods, and other germanium and silicon samples with which he could per- form resistivity and Hall measurements. He wanted these soon, “so that we can get the experiments organized.” Fisk obliged. During the fall of 1951 Holonyak also heard Bardeen give his first Urbana seminar on the transistor. The lecture became vividly imprinted in Holonyak’s memory. Bardeen arrived with a trans- parent box, “about eight or nine or ten inches long and about six or seven or eight inches high and three or four inches thick.” It was the music box that Bell Labs had made for him in 1949. The box had “a little loudspeaker on the front, and it had two of these point contact transistors sitting in some sockets and a battery.” But what it did was infinitely more exciting than how it looked. As soon as he flipped the switch on, the thing started to play, and I almost fell out of my seat because I was already a grad student, and I knew how to build things out of vacuum tubes. You turn it on and you wait for the filaments to warm up, and you wait for a consider- able time before the thing does anything. This thing, whatever it was doing, the magic, turned on immediately as soon as the power was turned on. I knew right away, “Oh-oh, this man has got some- thing different sitting here in our face.” Holonyak remembered that Bardeen taught the new course on semiconductors and transistors using a loose-leaf notebook cradled in his left forearm, fingers curled around the top. He again used Bill Shockley’s text, Electrons and Holes. During the Second World War, John told the class, scientists had been studying metal–semi- conductor junctions for use in radar. To illustrate, he drew a dia- gram on the chalkboard, with the “barrier facing the metal on the left and the semiconductor on the right.” Holonyak said, “I remem- ber him pointing with the chalk at the holes and smiling a little bit, just a little hint of a smile, saying that if Schottky had looked there to see what the holes were doing, the transistor would have been invented.” 

176 TRUE GENIUS Bardeen’s mention of the German physicist Walter Schottky was an understated reference to his own major contribution to transistor history, to the recognition that in his work with Walter Brattain the holes entering the germanium were the key to the transistor’s action. Schottky and the British physicist Nevill Mott had been among the first to develop a viable theory of the rectifica- tion due to semiconductor-to-metal interfaces. Working at the Siemens Laboratory in 1938, Schottky had attributed the rectifica- tion to an observed potential barrier at the interface, increased by an applied voltage in the back direction of the current and decreased by voltage in the forward direction. In 1945, when Shockley sketched the field effect design that started Bardeen on his transis- tor research, the Mott-Schottky theory was at the cutting edge of rectification physics. But the theory did not take into account the surface states that Bardeen postulated in 1946 or the holes that would feature prominently in Bardeen and Brattain’s transistor. When Holonyak learned that Bardeen was going to set up a semiconductor laboratory, he recognized it as an “opportunity to get into something fresh and original.” He asked his advisor—the electrical, cybernetics, and computer engineer Heinz von Foerster— if it would be all right for him to become Bardeen’s student. Von Foerster agreed. Bardeen and his first graduate student became instant and unlikely friends. While Bardeen came from a middle-class academic family, Holonyak was the son of a southern Illinois coal miner. Unlike the mature, soft-spoken, and meditative Bardeen, Holonyak was young, garrulous, and exuberant. Years later the Champaign- Urbana News Gazette described Holonyak “as animated as Bardeen is dry; as effusive as Bardeen is self-contained.” He was another of the “voluble and extroverted and enthusiastic” people for whom Betsy said her father had an affinity—like John’s brother Bill, Walter Brattain, or Walter Osterhoudt. Holonyak intuitively understood both sides of the strong bond between Bardeen and Brattain. He recognized that Brattain’s fre- quent visits to Urbana in the early 1950s were because “he missed his partner.” On one particular visit, Holonyak happened to observe Brattain and Bardeen working together in Bardeen’s semiconductor laboratory. Brattain was scribbling on a blackboard while talking and gesturing excitedly. He was having trouble with a calculation. Finally, Bardeen inserted himself into Brattain’s problem, mum- 

Homecoming 177 bling the explanation as he scratched numbers and symbols on the board. Brattain eyed Bardeen over his half-glasses as both stepped back to admire the solution. “Goddammit, John,” Brattain burst out, “how in the hell did you do that?” To Holonyak it appeared that Bardeen was the “head” in the relationship, while Walter was the “hands,” as well as the one who did most of the talking. In the electrical engineering department, Bardeen continued to work on semiconductor physics. One goal was to establish an ex- perimental semiconductor group in the Electrical Engineering Re- search Laboratory (EERL). Holonyak and Richard Sirrine were the first two graduate students in the semiconductor lab; the first two postdoctoral researchers were Harry Letaw, Jr., a physical chemist, and S. Roy Morrison, a solid-state physicist. Bardeen directed them in an informal paternal fashion. The semiconductor laboratory, when it began functioning in the fall of 1952, was initially housed in a large, empty room that had previously contained the university’s historic ILLIAC com- puter. The ten-foot-long, two-foot-wide computer, which was just becoming operable at the time Bardeen’s group began setting up their laboratory, left behind ample work space when it was moved to another building. Bardeen’s work replaced the ILLIAC in another way, too. Based on vacuum tubes, the ILLIAC would soon become obsolete in the wake of transistor technology. The behemoth com- puter had required so many (2,800) vacuum tubes to drive its forty- bit parallel memory that a parade of students had to regularly come through with bushel baskets full of tubes to replace the defective ones. Bardeen wrote grant proposals to support his students and equip the semiconductor lab. Holonyak worked with the others to con- struct items that were not yet available commercially. Although the lab was well funded by government agencies, such as the Office of Naval Research and the Air Force Office of Scientific Research and Development, it was not fancy. Bardeen never lost the “sense of economy” that Althea had noticed when he was a boy. Some members of the group grumbled that his funding requests were too modest. They felt that a scientist as eminent as Bardeen should have been given an exceptionally well-equipped lab with cutting- edge materials and equipment. Holonyak soon figured out that his mentor “didn’t need anything lavish.” What he cared about was that the problems were good ones. “He didn’t need anything to 

178 TRUE GENIUS pump up his ego,” because “John Bardeen knew that he was John Bardeen.” Bardeen believed that both theorists and experimenters needed a solid grounding in experiment, as he had had. He sent some of his early theory students, including Robert Schrieffer, over to work in the semiconductor lab for a while and get their hands dirty. “I thought that even theorists should have some lab experience.” Later, Bardeen recognized that studying both theory and experi- ment was too much to expect if a student was to finish a thesis expeditiously. An apocryphal story features John Bardeen offering his two early graduate students—Holonyak and Schrieffer—a choice between semiconductor research and the superconductivity prob- lem. “The semiconductor topic,” he is reputed to have said, “is guaranteed to generate results if you work hard enough. The super- conductivity topic is different. It can lead to an unbelievably great work. But it also has a risk of generating no results at all.” The story is dramatic but fanciful. Holonyak worked in Bardeen’s semi- conductor laboratory from his earliest association with his mentor and never considered the more theoretical topic of superconductivity. Moreover, by the time Schrieffer got to the point of thinking about a thesis project, Holonyak had already finished his thesis (1954) and moved on to Bell Labs. James Bray, a much later theory student of Bardeen’s, felt that he absorbed Bardeen’s predilection to root his work in experiment even without having laboratory experience. “For whatever reason, I had by then developed, and still have, a strong desire to be around experimentalists,” Bray acknowledged. “It just happened naturally. There are theorists who like to work with theorists and be around theorists and be theoretical all the time.” That had never been Bardeen’s style. “John would occasionally call those people ‘theorist’s theorists’—and he wasn’t using the term in a compli- mentary fashion as some other people do.” Bray explained that Bardeen “thought it was very important for theorists to immerse themselves in experimental data and be guided by that.” He did not appreciate a theorist “who just sat down and would plot down a bunch of equations . . . whether or not it bore any relation to reality ultimately.” In the first years of the semiconductor lab, Bardeen came by almost every day to find out what the students had been doing and 

Homecoming 179 whether they needed help. He always asked about the materials being used. Although he never “picked up a pair of pliers,” he encouraged his students to find out for themselves how to design an experiment and interpret results. Bardeen greatly appreciated Holonyak’s hands-on ability in the laboratory, as he had, similarly, appreciated Brattain’s. Holonyak soon learned that his mentor was not the best person to answer questions about the details of an experiment. Before he got to know Bardeen well, Holonyak “would go up to him when he would come in, and I would say, ‘what do I use to do this, a hydrogen atmosphere or a vacuum?’” Bardeen “would just look at me. He wouldn’t say anything.” After a while, “I began to understand that he didn’t do experimental work. I was asking him things that he wasn’t familiar with. And he didn’t say anything just because there wasn’t anything to say, and he wasn’t going to talk just for no good reason at all.” When Holonyak left for Bell Labs in 1954, Paul Handler came on board as a postdoc to work in the semiconductor lab. Bardeen emphasized the work’s importance for the government when he wrote a letter in support of extending Handler’s military deferment. “It is known,” Bardeen wrote, “that Russia is training scientists at a much faster rate than we are, so that it is urgent that we make the best possible use of our trained people.” Handler recalled that Bardeen “knew what were important problems in semiconductor physics.” Moreover, he was “very aware of other experimental work.” For example, Handler “didn’t know about the ultra-high vacuum work that had been done at Brown University,” but Bardeen did, and he “sent me out there to find out how it was done.” Bardeen gradually relinquished control of the lab to Handler. At first, “he’d come by about twice a week, maybe three times a week, stop in and see how things were going.” After some time, “he came in once a week.” By 1962, Bardeen was spending little time in the semiconductor lab. Nor did he need to worry about writing grants or obtaining funding for graduate students. Eventu- ally Handler “wrote them with just my name alone. So essentially there was a transition.” Holonyak had not been at Bell Labs a year when he was called to serve in the army. Bardeen was concerned about Holonyak’s career. He told Holonyak to try to get assigned to a government laboratory where he could continue to do research. Bardeen gently 

180 TRUE GENIUS prodded him, “If you can possibly do it, I hope you can revise your thesis for publication before you leave. . . . You did a very good piece of work; it should not lie buried in government reports.” He also made the first of a series of offers to Holonyak to come “home” to Urbana. “If you ever have a desire to return to Illinois please let me know. I feel sure that we could work something out that would combine teaching and research.” Five weeks later Bardeen wrote again: “I know the indirect pres- sure to produce can be very great. We would certainly welcome you back if you would like to join the staff here.” In October 1955 Holonyak married Katherine Jerger, who was then attending gradu- ate school at New York University. She went home to Chicago and took a teaching position while he was away in the army for two years. When Holonyak learned that he would be stationed in Japan, Bardeen encouraged him to call on Hatoyama and Kikuchi. Hatoyama, Bardeen wrote Holonyak, “is a very nice fellow, and I am sure he would enjoy meeting you.” For the next eight months Holonyak visited both Japanese scientists “every other weekend,” and they became good friends. Hatoyama wrote to Bardeen that Holonyak was “a nice fellow” and that “he was always talking of his wife.” In the fall of 1957, Holonyak returned to industrial research, working at General Electric for the next six years. Periodically Bardeen would urge him to consider returning to Illinois. “I think there are some real advantages to being in a university commu- nity,” he wrote Holonyak in 1959. Four years later when Holonyak finally returned to Urbana, Bardeen resumed his habit of regularly visiting his young friend’s semiconductor lab. Teaching large groups of students remained a chore for Bardeen and for some of the students. Many could not interpret his muffled speech nor his odd silences. For some students, his frequent pauses to think or scratch an equation on the board had a soporific effect. Sometimes he pressed the chalk to the board so lightly that it was barely possible to make out the characters. Sitting close to the front of the room was therefore important. Andy Anderson recalled that a class he took with Bardeen was on the third floor, “and when our previous class was over, we all ran like hell up the stairs to try to get a front seat.” In the mid-1950s physics graduate students were called upon 

Homecoming 181 to spoof their professors in skits at the annual department party. Bob Schrieffer, who had been working with Bardeen since the fall of 1953, “found a dark blue suit, a white shirt, and a dark blue tie.” He climbed to the stage and “began to lecture before a group of students on the stage, saying in a soft voice, ‘You are going to sleep, you are going to sleep.’” He was a little concerned about how his mentor would react to the parody, especially when he saw Bardeen flush bright red at the burst of laughter that greeted Schrieffer’s gentle mockery. At the next class meeting Bardeen announced with a mischievous grin that he had reserved the auditorium for his lec- ture, “so that they could sleep more comfortably.” Schrieffer sus- pected that Jane had “had a hand in this genius move.” Some students found it unnerving when Bardeen would explain something in exactly the same words every time he was asked. “He would simply repeat, almost like a tape recorder,” a teaching method not helpful to a student who had not understood the expla- nation to begin with. Many students ended up dropping out of his courses. Other students found Bardeen’s teaching methods exception- ally stimulating. His habit of stopping to think offered them the chance to do the same. “He was fascinating to listen to,” recalled Holonyak, “because you were invited into what he was doing. If he paused and he was thinking, you realized that he was thinking, and you thought.” Bardeen viewed student participation as one of the most important aspects of the learning experience, for under- graduates as well as graduate students. He helped them to develop confidence by encouraging them to find answers for themselves. “You can figure it out,” he would prod them. Bardeen and his students—and their students—illustrate Harriet Zuckerman’s theory of “mutual influences,” in which sci- entists pass their values on to succeeding generations in a kind of socialization process. Bardeen’s students learned from him how to identify important problems, how to attack them, and what consti- tutes a solution. According to Zuckerman, master scientists reinforce in their students “not only cognitive substance and skills but the values, norms, self-images, and expectations that they take to be appropriate for this stratum in science.” Bardeen’s style of teaching was reminiscent of his father’s. Dean Bardeen had been well known for his muffled speech and hands-off approach to teaching. Charles hoped that his students would “take 

182 TRUE GENIUS on the spirit of the investigator, the delight in first hand informa- tion about natural phenomena, the willingness to work hard to get at the truth.” But he pointed out, “This spirit will not be aroused in the student by one who is not himself filled with it.” The teach- ing method of both father and son required students to have confi- dence and persistence. Bardeen “would not impart motivation,” said Bray, “if you didn’t have it.” The students who came away with an understanding of Bardeen’s lessons were the ones who par- ticipated in the learning experience. He encouraged them to stretch their imaginations and bury themselves in the literature to which he directed them. Even the best students had to work hard to navigate Bardeen’s leaps of thought. “Often,” Schrieffer said, “it would sound like he was giving a logical explanation when it was nothing but reading out steps 3, 17 and 42.” Many students and colleagues had diffi- culty filling in the missing steps. Schrieffer himself adopted a “standard technique” to get more detail from Bardeen. By saying “things that were slightly wrong,” he exasperated Bardeen just enough so that “he’d talk more.” To teach students to solve problems, Bray said that Bardeen “would sort of outline the problem and then indicate the direc- tions you ought to go work on—what sort of things you ought to try to compute.” One time, “he just walked in one morning, wrote a suggestion on the black board and walked out.” Although “he did this in five minutes,” it was just what they needed to help them with their calculation. “From what he wrote there we had it done by the end of the day.” Schrieffer had at first been unnerved by his mentor’s commu- nication style. “Often he would sit for 8 or 10 minutes. He’d say nothing, and I found this terribly disquieting.” Students would ask themselves, “Have I said something stupid?” Bardeen’s students learned that “he was just thinking. Sometimes you’d walk to the door and the door would be half way closed and he would start speaking to the empty chair.” For many people conversation is a way of organizing thoughts that are incomplete out loud. Schrieffer came to “realize that usual conversations about serious research move much too rapidly for people to think deeply.” Bardeen pre- sented a different model. “You should rather get your thoughts in place and eliminate a lot of silly nonsense that you talk out.” After Bardeen’s long stretches of silence, what he finally did articulate was “meaningful.” 

Homecoming 183 Bardeen’s public presentations were often even more concise. He uttered “one sentence,” recalled his colleague Chih-Tang Sah, “one phrase or one sentence, that defined the problem—the whole thing. The details you can work out or he’ll give you a simple example on the blackboard.” Student experiences with Bardeen varied. Some hesitated to ask him questions, worrying that he would think them incompe- tent or lazy. For others, despite his policy of keeping his office door open, “he always appeared too busy to encourage idle questions.” Bardeen politely hid any irritation he may have felt for less able or less confident students who approached him with questions he con- sidered trivial. But he did not waste time explaining things that had already found their best exposition in the literature. Dan Mattis, who worked with Bardeen in the 1950s, tried not to approach him with a problem until he already had some reasonable approximation of an answer. “The best strategy appeared to be to try to understand just what he had had in mind, then return, as soon as possible, with the final results.” Other students always felt welcome in Bardeen’s office. “Bardeen was extremely accessible,” said David Allender, who finished his doctoral dissertation in 1975. “If I wanted to talk to him he always made time.” Henry Pao, who completed both his undergraduate and graduate degrees at Illinois, recalled that when he had questions he “always would go to Bardeen and he wasn’t afraid to ask.” Bardeen was not given to lengthy explanations, but he “would give you leads to things that you can research and then understand.” Pao suggested that engineers are “more practical” and therefore not as inclined as physicists to put a man like Bardeen on so high a pedestal that they were afraid to approach him with practical questions. Colleagues would consult with Bardeen when they reached a barrier in their research. “He was the one I would go to when I was stuck,” recalled Lazarus. Paul Coleman would sometimes walk over from engineering to ask a question. Typically they would chat for a moment about their mutual passion for golf, then Coleman would pose his question. He appreciated the fact that Bardeen never embarrassed him by saying, “You mean to tell me you don’t know that!” Dan Alpert thought that “one of the reasons that people respected him so highly is that if you went in and asked him ques- tions that reflected whatever level of knowledge you had, you never had to prove yourself to him.” 

184 TRUE GENIUS Asked once what Bardeen was like as a teacher, Alpert said it “depends on who you think his students were.” To him, Bardeen “was one of the great teachers on this campus and his students were the faculty. He had some graduate students of course, but the whole physics faculty were his students.” Bardeen treated every colleague as an equal. “When I had a specific technical question to ask, he got to the heart of the issue. He didn’t mess around with all kinds of talk, and the last thing on his agenda was to impress you with how much he knew.” Bardeen took a humane approach in working with students. When he sat on George Russell’s thesis committee, he made no comment when Russell told the committee that he could not find any literature about one aspect of his proposed study. But “after it was over, [Bardeen] came up and gave me a reference to some obscure journal.” To Russell it appeared that Bardeen “knew every- thing that was going on in his field.” Bardeen occasionally helped the students of other professors. John Wheatley suggested that his student, Andy Anderson, go see Bardeen about the interpretation of some of his experimental re- sults. They differed by a factor of two from those of the eminent Russian theorists, I. L. Bekarevich and I. M. Khalatnikov, given in a calculation of the Kapitza thermal boundary resistance at the in- terface between liquid 3Ηe and a solid. Bardeen watched silently while Anderson scribbled his figures on the blackboard. After the younger man stopped speaking, Bardeen sat gazing into space. Anderson backed toward the door uneasily and reached for the knob. Suddenly Bardeen started talking. He told Anderson that he knew the Russians’ work and that it was unlikely they had made such a mistake, but he was unwilling to make any definite pronouncements on a subject that he had not thoroughly thought out himself. “I then escaped feeling very embarrassed at having bothered him with my stupid ideas,” recalled Anderson. However, some months later Bardeen assigned the problem of the factor of two to a new French postdoc, J. Gavoret, who found the source of the error and published it in the Physical Review. “Only then did I realize that Bardeen had taken me seriously.” Bardeen never took on more than a few graduate students at a time (see Figure 10-1). One of his star students in the early 1960s was William McMillan. A true individualist, McMillan had a pro- nounced stutter, a magnificent beard, and a penchant for applying 

Homecoming 185 FIGURE 10-1 Bardeen’s graduate students, 1952-1974 Name of Student Dissertation Title Year Paul J. Leurgans Interaction of Excitons and Impurity 1952 Atoms with Phonons in Germanium Nick Holonyak, Jr. Effect of Surface Conditions on 1954 (electrical engineering) Characteristics of Rectifier Junctions Thomas Nolan Morgan Photoconductivity in Germanium at Liquid 1955 Helium Temperatures Newton Bernades Theory of the Specific Heat of Superconductors 1957 Based on an Energy Gap Model Daniel Charles Mattis Conductivity Problems in Quantum Theory 1957 J. Robert Schrieffer The Theory of Superconductivity 1957 R. C. Sirrine An Investigation of the Surface States on 1957 (electrical engineering) N-Type Germanium Michael Francis Millea Effect of Heavy Doping on the Diffusion of 1958 Impurities in Silicon Milton William Valenta Effect of Heavy Doping on the Diffusion of 1958 Impurities in Germanium Ling Yun Wei Diffusion of Silver, Copper, Cobalt, and Iron 1958 (electrical engineering) in Germanium Stephen Reynolds Arnold Effect of Ion Bombardment on Semiconductor 1959 Surfaces William Manos Portnoy The Conductance of a Cleaned Germanium 1959 Surface Richard Elmo Coovert Surface Magnetoconductivity Experiments on 1960 Silicon Piotr B. Miller Frequency Dependent Hall Effect in Normal and 1960 Superconducting Metals continued on next page 

186 TRUE GENIUS FIGURE 10-1 Continued Name of Student Dissertation Title Year Rolland A. Missman, Jr. Galvanomagnetic Properties of Carriers Associated with the Cleaned 1960 Germanium Surface Kendal True Rogers Superconductivity in Small Systems 1960 Toshihito Tsuneto Part One: Transverse Collective Excitations 1960 (thesis submitted to in Superconductors and Electromagnetic Kyoto University, Japan) Absorbtion. Part Two: Ultrasonic Attenuation in Superconductors Jerome Luther Hartke Drift Mobilities of Electrons and Holes and 1961 Space-Charge-Limited Currents in Amorphous Selenium Films Kenneth Rose A Microwave Technique for the Study of 1961 (electrical engineering) Deviations from Ohm’s Law in High Resistivity Superconductors Peter Vance Gray Tunnelling from Metal to Superconductors 1962 Daniel Warren Hone Spin Diffusion and Other Transport Properties 1962 of Liquid He3 William L. McMillan Ground State of Liquid He4 1963 John Warren Wilkins Part I: Tunnelling in Superconductors: 1963 Second-Order Processes and Lifetime Effects Part II: A Contribution to the Theory of the Electron-Phonon Interaction Wayne Earl Tefft A Theory of the Electrical Resistivity of 1964 Liquid Metals John Richard Clem Effects of Anisotropy of the Superconducting 1965 Energy Gap Wesley N. Mathews, Jr. Bogoliubov Equations and Their Application to a 1966 Normal Superconducting Boundary 

Homecoming 187 FIGURE 10-1 Continued Name of Student Dissertation Title Year Sang Boo Nam Theory of Electromagnetic Properties of 1966 Strong Coupling and Impure Superconductors Reiner Kümmel A: Schichtdicken-abhängiger Quantisierungseffekt 1968 (thesis submitted to in Tunnelkontackten Goethe-Universität, B: Untersuchungen zum Zwischenzustand Frankfurt, Germany) und gemischten Zustand von Supraleitern I. und II. Art. David William Allender Model for an Exciton Mechanism of 1974 Superconductivity in Planar Geometry James William Bray Fluctuation Conductivity from Charge 1974 Density Waves in Pseudo-One-Dimensional Systems Jared Logan Johnson Current Flow in Inhomogenous Superconductors 1974 ingenious methods to challenging problems. For his thesis he con- vinced Bardeen to let him apply Monte Carlo statistical sampling methods to calculate properties of the ground state of superfluid helium. In this state, analogous to the state of superconductivity except that the particles have no charge, the fluid flows without friction. Bardeen knew little about Monte Carlo methods but felt he could rely on McMillan to judge whether they would apply in this case. McMillan completed his doctorate in 1964 and took the department’s annual award for best Ph.D. thesis. Following a stint at Bell Labs, where he worked with John Rowell deducing lattice vibration spectra in superconductors from tunneling data, McMillan returned to Illinois in 1972 as a profes- sor. Once back in Urbana he continued to work on liquid crystals, light scattering, heat capacity measurements, and charge density waves, as well as electrically driven structural phase transitions and their interactions with superconductivity. Bardeen had the highest regard for McMillan, whom he once described as “very 

188 TRUE GENIUS bright, original—needs self-discipline.” He later retracted the last bit and said that McMillan “was probably putting in his time to a better advantage than studying the things required for courses.” He told McMillan in 1978 that his “work on deriving phonon spectra directly from tunneling data” has had a great “impact and is one of the main reasons why superconductivity has been called the best understood of solid-state phenomena.” The strength of the bonds that formed between Bardeen and his many students and postdocs brought many of them back to the University of Illinois, at least for a time. The Bardeens often in- vited students and colleagues as well as friends to their house, es- pecially in their early years in the community when Champaign-Urbana offered few restaurants or entertainments. Jane would do the cooking and planning, usually keeping it simple. “It was very informal and very spontaneous.” Everyone appreciated her hospitality and warmth. In her presence people felt at ease and attended to. On social occasions, “I always immediately ran to Jane, because she was easy to talk to,” said Karl Hess, a postdoc from Austria, recalling his early days in Champaign-Urbana. To Hess and his wife, their first Christmas in the United States looked dismal until the Bardeens invited them over to celebrate Christ- mas Eve. Hess remembers John showing the two toddlers his med- als and a strange golf ball that had a transistor radio inside. Another year, when postdoc Ludwig Tewordt and his wife found it impos- sible to visit family in Europe at Christmas, John and Jane stopped by their apartment on Christmas Day bearing gifts for their three children. In recalling social events at the Bardeen home, students typically used the words “relaxed” and “informal.” The house was furnished for comfort rather than elegance. The kitchen was the focal point. Photos cluttered the piano top. The walls held art from the Harmer side of John’s family. Shelves overflowed with books and mementos from trips. The entire effect was modest. Neither John nor Jane ever thought of themselves as wealthy or socially upper crust. Hess recalls that he and his wife arrived dressed up for their first party at the Bardeens’ and were shocked to see everyone else in shorts. Even more surprising was to find Bardeen, the great Nobel Prize winner, in the kitchen serving drinks. Bardeen continued to be extremely popular with young chil- dren, with whom his reserve melted. He often viewed the world 

Homecoming 189 through childlike eyes, diving under the bedcovers to play “loon” with his grandson, or playing jacks on the porch floor with the children of friends. Tom Bardeen, John’s nephew, basked in the feeling that he had “Uncle John’s” undivided attention whenever they interacted. Ned Goldwasser remembered one “absolutely superb” experience at a department picnic. When one of his children screwed up his courage and asked Bardeen a question about relativity, the Nobel laureate did his best to explain the theory in terms the ten-year-old could understand. When the Bardeens entertained they often issued special invi- tations to the children of their guests. One of the authors will never forget the afternoon in 1985 when Bardeen personally telephoned to invite her young son, Michael Baym, and infant daughter, Carol Baym, to a party. Some years later when Bardeen passed away, nine-year-old Michael felt that he had lost a friend and insisted on attending the memorial held in Bardeen’s memory. For his own children, John was the model of a scientist engrossed and happy in his work. As the children grew older he often had answers for their questions about nature. His approach, as Jim interpreted it, was “opening doors, but not trying to force us through them.” The method worked well enough to interest all three Bardeen children in the physical sciences. Jim and Bill became physicists. Betsy studied anthropology, then computer program- ming. In 1966 she married a physicist, Tom Greytak.