Witness to Revolution

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Linus Pauling did more at Oregon Agricultural College than learn science and fall in love. He began to build a strong sense of self-confidence, a belief in his abilities to teach and to think critically. And he enlarged his understanding of society. His ceaseless reading included the stories of the French writer Guy de Maupassant, with their lessons about human nature, and the plays of the British social critic George Bernard Shaw, whose wit and insight started him thinking about the many ways in which a society built around privileged classes and private wealth could hurt its poorer and less fortunate members.

Most important, Ava Helen spurred his thinking about the issues of the day. She came from a politically active, left-wing family. Like Shaw, she was attracted to a political system called socialism. Socialists believed that the fairest society was not one in which a few wealthy people owned the means of making and distributing goods—the system in place in the United States and many other nations—but one in which all the people, rich and poor, shared ownership of the factories and railroads, shipping lines and newspapers. Ava Helen grew up amid long discussions about

Linus Pauling in 1925 after receiving his Ph.D. from Caltech. He would spend most of the next two years in Europe, learning the revolutionary new ideas of quantum physics.

women's rights and the wrongs of the American economic system. Pauling, although he was more interested in chemistry than anything else, began listening to Ava Helen's ideas, too.

Linus Pauling was learning to become more than a single-minded scientist. Slowly he began developing an interest in human affairs and science's role in society. At his OAC graduation ceremony, in the spring of 1922, he gave the senior oration, a formal speech in which he hinted at his expanding concerns.

"Advancement and growth depend upon the discovery and development of the resources of nature, and the investigation and interpretation of the laws of nature," he told the crowd of parents, professors, and students. "In the course of progress social relations are strained, and industrial, political and educational problems arise. The country is crying for a solution of all these difficulties, and is hopefully looking to the educated man for it. This, then, is the way we can repay OAC—by service . . . service to our fellow men."

This growing moral sense helped push Pauling away from his original goal of becoming an industrial chemical engineer and toward science at a higher level. He wanted to teach and do important original research that would make a significant difference in the history of chemistry. He wanted to be a university professor.

To reach that goal, he knew that he would need a doctoral degree, so he applied to a number of graduate schools during his senior year. Many accepted him, including Harvard, the University of Illinois, and the University of California at Berkeley. But a combination of haste and need led him to say yes to the school that responded most quickly with the most generous offer of support: the California Institute of Technology.

Caltech, as students called it, was a gamble for Pauling. It was a very young school with a small campus in Pasadena. It was not yet as well known as the other programs he had applied to. But Caltech had something the other schools did not.

Caltech had Arthur Amos Noyes, an internationally known chemical theorist, a money-making inventor, the author of widely used textbooks, and a great teacher. Noyes had become something of a legend by transforming the chemistry department at the Massachusetts Institute of Technology into the envy of the world. He then had been lured to Caltech by the offer of a great deal of money, a new laboratory building, and a free hand in developing the school's curriculum.

Noyes arrived full-time in 1919, bringing with him his stellar reputation, a gentle manner, and a commitment to build a school where science would be taught in a new way. Noyes believed deeply that all the sciences should learn from one another, a lesson he had learned from his own master, a great German chemist named Wilhelm Ostwald. Ostwald had moved chemistry forward by infusing it with the techniques and mathematical approach of physics, helping to create a new field called physical chemistry. At Caltech, Noyes made certain that chemistry students also learned everything possible about physics, mathematics, biology, and the humanities, whenever possible in small seminars that emphasized the latest research findings. He encouraged an atmosphere in which students and professors regularly interacted, formally and informally, whether in laboratories or on camping trips. He would make Caltech, as he had MIT, a renowned center for the study of chemistry, a sort of chemical Camelot that drew the best researchers and teachers. In turn, Noyes's students gave him the appropriate and affectionate nickname of King Arthur.

Pauling knew of King Arthur and was thus flattered when Noyes wrote him personally the summer after his graduation from OAC, asking questions about his academic background, sending him the galley proofs of a new textbook he was writing, and asking Pauling to solve the 500

test questions at the ends of the chapters. Pauling worked on the questions in the summer evenings after graduation. "I learned a great deal about physical chemistry during the three months of the summer," Pauling remembered. He solved every one of Noyes s problems—and impressed King Arthur by suggesting improvements in his text.

When Pauling boarded the southbound train to Pasadena at the end of the summer of 1922, Ava Helen was not with him. The news of their engagement had come as an unpleasant shock to both of their mothers. Belle Pauling felt her son was too young to marry and would be unable to support his wife on a graduate student's stipend. Ava Helen's mother thought her daughter was throwing away her chance for a college degree. Both strongly advised their offspring to put off marriage. Reluctantly, the young lovers agreed.

Though Pauling missed Ava Helen deeply, he was also caught up in the excitement of moving to a new place. He had never been to California, and he found that he liked Pasadena—a small, wealthy bedroom community of Los Angeles—a great deal. The climate was Mediterranean, the colors pastel, the sun warm, the air soft. There were palm trees and orange groves. It was a welcome change from the dark winters, gray-green fir forests, and chilling rains of Oregon.

Pauling threw himself into his studies. During his first year at Caltech, he remembered, "I had, I think, 45 hours (which at some universities would be called 15 hours) of classwork. Later on, the department made a rule that a teaching fellow could only sign up tor 30 hours. In addition, I spent a lot of time on research. After dinner, I would go back to the lab and work until perhaps 11 o'clock at night. On Saturday and Sunday, I'd just work all day."

In order to save money, Pauling shared a bed with Paul Emmett, an OAC friend who was also attending Caltech. Thev used it in sequence, with Emmett sleeping until

Pauling returned from the laboratory and finished writing his daily letter to Ava Helen at around three o'clock in the morning, then Pauling turning in while Emmett got up to study.

It was hard work and the hours were long—and Pauling loved it. He found that Caltech, new as it was— there were only 10 graduate students in chemistry—was a great place to learn science. Pauling had taken a great deal of chemistry while at OAC, but very little mathematics or physics. Now he made up for this deficiency by learning advanced calculus, vector analysis, integral equations, complex numbers and potential theory, classical physics and quantum theory, advanced physical chemistry, and atomic spectroscopy. He attended weekly seminars in astronomy and physics that often featured visiting scientists and leading researchers from around the world. From them he learned of the very latest and most exciting scientific advances, sometimes even before they were published.

Pauling (front row, far right) poses with the faculty and graduate students of Caltech's chemistry department in 1923. As a graduate student Pauling impressed his Caltech professors by mastering both laboratory research and theoretical inquiry.

Intellectually, Pauling had never been happier. Emotionally, things were not going as well. As time went by and a date for their wedding seemed to come no closer, the tone of Ava Helen s daily letters shifted toward the accusatory; she wrote that she thought Pauling was delaying their marriage to satisfy his personal ambitions. He replied that he had agreed to put off the marriage only in order to be better able to support her, writing that "your happiness means everything to me, dear heart, when my heart is so full of love for you."

To keep her happy, Pauling agreed within months of starting at Caltech that they would get married the following summer. During the school year, he bought a used Model T Ford from a professor for $50 and learned to drive it by taking it around the block a few times. As soon as his first year was over he headed north to Oregon. In June 1923 he and Ava Helen were married in a small family ceremony at her sister's house in Salem. After a one-day honeymoon, Pauling started another summer job of testing pavement for Oregon road crews. But this time he had a young bride with him.

It was a euphoric summer. The Paulings moved from town to town with the road crew, staying in cheap hotel rooms and shabby apartments up and down the Columbia River. They learned everything about each other—some of it, from Pauling's standpoint, surprising. One weekend Pauling checked out a book on intelligence tests from a local library, and he and Ava Helen began answering the questions together. "Much to my astonishment," he said, "I found that my newly acquired wife could work these mathematical problems faster than I could, and get the right answer more often than I could." More important, they both learned that they had found true soulmates, equals intellectually as well as emotionally. Theirs would be a deep, lifelong love.

In the fall, the young couple took up residence in a modest house near Caltech. They did not have much money to live on, but Ava Helen proved adept at stretching what they had. She became an accomplished cook and spent time keeping the tiny house clean. But she was too bright and spirited to be a stay-at-home wife. The all-male faculty and student body of Caltech were amused to see her accompanying her husband to occasional classes during the day. In the evenings, they were always together in the laboratory, where she helped him make measurements, draw diagrams, calculate figures, and keep his laboratory notes. Ava Helen would never be relegated to the role of a traditional wife. She was determined to be more than a background figure who ran the house while her husband worked.

Graduate students in chemistry are expected not only to learn in the classroom but to prove that they can make discoveries in the laboratory. This part of their training is done in the laboratories of major professors who guide their work, teaching them both how to handle equipment and how to conceive experiments that will answer important questions. Pauling's major professor, Noyes decided, would be Roscoe Dickinson, a young professor who served as Caltech's resident expert in an exciting new technique that would become Pauling's most important scientific tool.

This procedure was called X-ray crystallography, and the way it worked was almost magical. Almost all solids exist in crystalline forms, in which the atoms are arranged in repeating three-dimensional patterns. Some crystals, including those in many metals, are too small to see with the naked eye. Others, such as rock salt or quartz, can grow very large. In 1912, a German physicist discovered that by shooting a beam of X rays at crystals and then analyzing the way the X rays scattered—their "diffraction pattern"— researchers could painstakingly work out, at least for simple crystals, the distances and angles between the atoms that comprised them.

This seemed incredible. The finest microscopes of the day could barely make out the bits and pieces inside living cells, but in one leap X-ray crystallography made it possible to pin down the positions of atoms 10,000 times smaller. It was true that the technique could be used only for very simple crystal structures—those with more than six or eight atoms in their repeating units gave diffraction patterns too complex to analyze—but even so, X-ray crystallography was beginning to do for the study of chemicals what Galileo's discovery of the telescope did for astronomy: change things forever. The structure of molecules, the way atoms joined together to build them, had been guessed at for decades. But without any way to verify these guesses, structural studies had thus far been deemed by most chemists to be a waste of time.

As Pauling took up the technique, only 10 years after its discovery, laboratories in Europe were already describing the atomic architecture of dozens of crystals, from rock salt to diamonds. They were confirming some old theories— finding, as predicted, that carbon atoms often join to make three-sided pyramids called tetrahedra—but throwing out others. Hard data about structure at the atomic level could now, for the first time in human history, be used to test chemists' ideas.

Under Roscoe Dickinson's guidance, Pauling learned how to use the finicky and complicated X-ray instrument, how to grow his own crystals, how to cut and polish them at specific angles, place them carefully in the apparatus, capture the X-ray diffraction patterns on photographic plates, measure the intensity and position of each important point, and analyze the patterns mathematically to see what they said about the atomic structure.

It was very hard work, with several things that could go wrong at each step, and at first Pauling experienced nothing but frustration. He spent three weeks trying to piece together the structure of one crystal, only to learn from a journal article that a Dutch team had beaten him to it. Again and again he took a preliminary look at different crystals, only to find that their structures were too complex to be analyzed.

After two months of frustration working with 15 different substances, Dickinson rescued him. The professor took him to the chemistry stockroom, grabbed a piece of molybdenite—a shiny black crystalline mineral composed of sulfur and molybdenum—showed him an innovative way of preparing it in thin slices, and helped him take the X-ray photographs.

Within a month, Pauling and Dickinson had pinned down its atomic structure. Molybdenite turned out to be moderately surprising, the first substance ever described in which six atoms of a nonmetal, sulfur, were arrayed in an equal-sided prism around a metal atom, molybdenum.

Pauling was elated. This was his first success in the laboratory, his first real discovery. "I was pleased to learn that questions about the nature of the world could be answered by carefully planned and executed experiments," he later wrote. The analysis of molybdenum's structure opened the door. He followed it by discovering the atomic structures of four more crystals over the next two years—a sparkling record of achievement for a graduate student.

But laboratory work would never be his first love. It was difficult for Pauling to slow his restless mind and find the patience needed for meticulous, repeated experiments. He loved coming up with new ideas and would most often, in later years, let someone else gather the experimental proof.

There was no doubt after his first months at Caltech that Pauling was doing well, and Noyes was pleased to see it. By Pauling's second year, Noyes was showing him special favor, asking Pauling's advice and introducing him to important visiting scientists. Thanks to Noyes's encouragement, Pauling, while still a graduate student, expanded his scientific work beyond the laboratory, cowriting theoretical papers with Peter Debye, an international leader in physical chemistry who was visiting Caltech, and Richard Tolman, a respected member of the school's chemistry division.

A wide scientific world was opening before Pauling, and he was interested in almost all of it, from the makeup of atoms to the structure of dwarf stars. But increasingly, one question began to stand out from among all the others.

It arose from the connections Pauling was making between the structure of molecules—the distances and angles between the atoms that comprised them—and their behavior, their melting and boiling points, the energy required to break them apart and re-form them.

Pauling believed that the two characteristics were intimately entwined. A full understanding of molecular structure, he thought, could explain a great deal—perhaps everything—about chemical behavior.

What was needed was a new way of understanding molecular structure from the bottom up, from the basic laws of nature. What determined structure? What dictated why atoms arranged themselves in certain ways but not others? What made the bonds between some atoms very strong and others weak? Underlying laws certainly determined these properties—rules of the sort that Pauling had read about in the papers of Gilbert Newton Lewis and Irving Langmuir— but Lewis and Langmuir had not gone far enough.

Pauling wanted to take the next step. At Caltech, in his many physics classes, he realized that in order to unravel the secret of molecular structure he would have to understand the nature of the atoms that made up the molecules, just as an architect who wants to make buildings has to know a great deal about the strength and capabilities of beams, bricks, and boards. Immersing himself in physics, Pauling began learning everything he could about the fast-changing theories of atomic structure. Things in this field were changing almost weekly as new findings came in from Europe, where a revolution in physics was taking place. A small group of young theorists had declared war on the idea

of the atom as a miniature solar system, with electrons zipping around the nucleus. This model left too many questions unanswered, they said, including why it was that the negatively charged electrons did not lose energy, as the laws of physics said they should, and fall into the positively charged nucleus. All of the debate was cloaked in difficult mathematics, and Pauling worked hard at Caltech to understand these new ideas. Then the Paulings' lives were changed in another way. In March 1925, Ava Helen gave birth to a son, Linus, Jr. It was a joyful event in many ways, but stressful in others. Intent on his work, Pauling did not change his schedule, continuing to labor late in the laboratory even after he received his doctoral degree, with honors, in June. But Ava Helen's life was transformed. The new baby meant she could no longer be her husband's laboratory mate. She now spent most of her days at home, washing, cleaning, and caring for the infant.

Just after Linus, Jr., was born, Pauling learned that he had won a Guggenheim Fellowship to study the new physics in Europe. He assumed that the baby would come along and was "shocked," he later said, when Ava Helen suggested leaving him with her mother until they returned. She pointed out the difficulty of traveling long distances with a baby in tow, with little time for dealing with the infant's needs and limited money for babysitters. After thinking it over, Pauling agreed. They would be apart from their baby for more than a year. There were good reasons for it, but their first European trip set a pattern: For Pauling, science and

The birth of the Paulings' first son, Linus, Jr., in 1925 come just as Linus learned that he had won a fellowship to study in Europe. The new baby was left in the care of Ava Helen's mother for more than a year while the young couple was overseas.

Ava Helen came first. His children would always place a distant third.

They arrived in Naples in the spring of 1926 and for several weeks enjoyed the honeymoon they had never really had, touring Rome and Florence, being jostled by the crowds in front of St. Peter's, and admiring the ruins at Paestum. It was glorious.

But Pauling was eager to get to work. He had arranged to study with Arnold Sommerfeld, one of the world's leading physicists, whose institute at the University of Munich was a nerve center for the development of new ideas about atomic structure. Short and slight, but still a commanding figure with his waxed mustache and dueling scar, Sommerfeld had a knack for turning out the brightest scientific minds in Europe. He knew everyone in theoretical physics, had collaborated on solving problems with the greatest of them, loved talking about the latest ideas with his students, and was a terrific teacher. Everyone who was anyone in physics corresponded with Sommerfeld, and he used the letters and prepublication papers that came to him from all the leaders in the field as fodder for his students.

When Pauling arrived, the institute was abuzz with a radically new approach to understanding the atom that had been proposed by one of Sommerfeld's former students, Werner Heisenberg. This young firebrand had decided to throw out any visualizable ideas of the atom at all and work instead with pure mathematics to explain the way atoms behaved. He came up with a system called matrix mechanics that was very difficult to use but provided answers that matched reality. His work was causing a furor among traditional physicists, who thought it absurd to form a theory without a physical picture of the atom behind it.

Then, just as the Paulings were settling into a tiny apartment a few blocks from the University of Munich, another, seemingly very different, theory was presented by one of Heisenberg's critics, the Austrian physicist Erwin

Schrodinger. In Schrodinger's view, electrons behaved not like tiny circling planets but like waves surrounding the nucleus. By applying the mathematics of wave functions, Schrodinger was able to create equations that also matched the observed properties of simple atoms.

Pauling heard firsthand the sometimes acrimonious debate between adherents of Heisenberg's matrices and Schrodinger's waves. In the summer of 1926 he saw Schrodinger present his wave ideas for the first time in Munich where the young Heisenberg jumped up at the end of the lecture to challenge his views. For a while it looked as though the physics world might split into two warring camps. But over the months Pauling was in Europe, it began to become clear that Schrodinger's and Heisenberg's ideas were not different realities but two different mathematical methods for arriving at the same atomic reality. Ultimately they became joined under a new name: quantum mechanics. Researchers, it seemed, could pick whichever method was easiest to use for a particular problem.

Pauling came to prefer Schrodinger's wave approach. "I find his methods much simpler than matrix calculations; and the fundamental ideas more satisfactory," he wrote a friend from Munich, "for there is at least a trace of physical picture behind the mathematics."

He then took Schrodinger's ideas to the next step. If electrons acted like waves, then what happened when two atoms joined together? Did the waves combine completely and now surround both of the nuclei? Or did the waves simply overlap a little? Pauling spent many nights in Munich working on this question, trying to tame Schrodinger's formidable equations and make them work to explain the bonds between atoms.

There was time for fun as well, however. Pauling had taken German in college and could now conduct passable conversations with the students, professors, and shopkeepers around him. He and Ava Helen went to the opera and text continues on page 40

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