Pauling, Linus Carl

(b. 28 February 1901 in Portland, Oregon; d. 19 August 1994 in Big Sur, California), renowned chemist and peace activist and the only person to receive two unshared Nobel Prizes.

Pauling was born and raised in Oregon. His father, Herman Henry William Pauling, was a modestly successful, self-taught druggist; his mother, Isabelle (”Belle”) Darling, was the descendent of a pioneer family. Pauling’s childhood was marked by tragedy, emotional isolation, and precocious independence. His father died when he was nine, leaving the small family, including Pauling’s mother and two younger sisters, alone and with limited means. Belle Pauling, devastated by the death of her husband and with her health crippled by pernicious anemia, used most of the family’s savings for a down payment on a boardinghouse on the edge of town. Driven by an anxious, often-bedridden mother, all three children worked at early ages to keep the house going.

After his father’s death, Pauling withdrew into books and hobbies. An interest in insects and minerals was followed, at age thirteen, by a fascination with chemistry spurred by a friend’s demonstration of simple home experiments using a toy chemistry set. Pauling gathered his father’s old pharmacy books, wheedled glassware from a drugstore salesman, smuggled chemicals and equipment home from an abandoned smelter, and created a homemade “laboratory” in a corner of the boardinghouse’s basement. Here he sought solace in learning the rules of chemistry and spent hours in free-form experimentation, much of it focused on the creation of substances capable of burning or exploding.

In high school a sympathetic chemistry teacher provided Pauling with special tutoring. This, combined with the attention of educated neighbors, helped the young man set his sights on college. By the time he was a high school senior, Pauling was self-confident enough to defy both his school principal, who refused to let him graduate early, and his mother, who wanted him to give up college in favor of a job in a local machine shop. At age sixteen he dropped out of high school and enrolled at Oregon Agricultural College (now Oregon State University), where he intended to pursue a degree in chemical engineering.

Away from home, Pauling blossomed. He quickly demonstrated that he knew more about chemistry than many of his professors. While still an undergraduate, he jumped at the chance to teach chemistry courses in the understaffed department, and he reaped two side benefits: greater access to current chemical journals, which he read avidly, learning the latest theories; and close proximity to dozens of young female students. One of the latter was an extremely bright and flirtatious Oregon girl named Ava Helen Miller. They were soon in love and married on 17 June 1923, a year after he received his B.S. degree from Oregon and after his first year in graduate school at the California Institute of Technology (Caltech). Miller remained a strong influence throughout his life.

Pauling developed an interest in the questions of how and why atoms bond together to make molecules, and Caltech, then a little-known, fledgling research institute, was a perfect place to study. He was one of the school’s first chemistry graduate students, beneficiary of a program devised by the renowned and innovative chemical educator A. A. Noyes. Pauling’s graduate work focused on a new and little-used analytical technique called X-ray crystallography, a complex and painstaking procedure in which beams of X rays were shot at crystals, the resulting scatter patterns visualized on photographs, and the patterns analyzed mathematically. If done correctly, the patterns indicated the positions of individual atoms in the crystal. Using this technique, researchers for the first time were able to map the distances and angles between individual atoms. The only problem was that the technique could only be used on very simple crystals. More complex substances yielded patterns too difficult to analyze. After a shaky start in the laboratory—Pauling’s talents were always more theoretical than experimental—he mastered the technique and earned his Ph.D. in 1925. At Noyes’s urging, he then spent fifteen months in Europe on a Guggenheim fellowship.

But knowing how atoms were arranged in molecules, something he could determine at least in simple cases with X-ray crystallography, was only half the story. Pauling also wanted to know the nature of the chemical bond that caused atoms to join together in certain ways and not others. To find the answer, he focused his studies on physics. His timing was propitious. In Europe a new and powerful advance in physics, quantum mechanics, was being born in the late 1920s, and Pauling was lucky enough to learn it from its creators, including Arnold Sommerfeld, Werner Heisenberg, Wolfgang Pauli, Niels Bohr, and Erwin Schrödinger.

After returning to Caltech as a young faculty member in 1927, Pauling embarked upon an extraordinary professional career, beginning the task of rebuilding chemistry on the foundation of quantum mechanics. His approach involved an intuitive mix of bold theory and empirical research, memorable lectures, persuasive papers, and best-selling textbooks. He was a communicator as well as an innovator. The new physics was mathematically challenging for all but a handful of chemists in the late 1920s, but Pauling knew how to simplify the math and describe results at a level chemists could quickly grasp.

He was also successful at discovering the structures of complex substances. Pauling used X-ray crystallography to gauge the distances and angles between atoms in simple crystals, then used the results as guides to what was or was not possible regarding more complex structures. By whittling down the possibilities, he was able to make highly educated guesses at structures for more complex substances. He would then toss the remaining theoretical structures in the wind of quantum mechanics, blowing away those that were not in accordance with the principles of the new physics. Once he eliminated as much chaff as possible, Pauling tested the best remaining structures by seeing how they looked, creating three-dimensional molecular models out of paper, wire, and wood. The single most plausible remaining structure he would test once again by predicting the ways it would behave, including its melting and boiling points and its X-ray patterns. If the model matched the qualities of the real molecule, he would publish his findings.

It was a brilliant approach and it worked. Pauling believed two things strongly: that rules of chemistry and physics determined how molecules were built, and that the structure of molecules explained their activity. He played both ends. Knowing the rules, he could eliminate and illuminate possible structures; knowing the structures, he could amend and refine the rules. His memory was prodigious and his approach independent. He appeared cognizant of few boundaries, dancing gracefully between physics and chemistry, laboratory results and theory. In a dazzling series of papers throughout the 1930s, Pauling made important advances in determining the structures of complex minerals as well as describing the chemical bond in quantum mechanical terms. This work was capped in 1939 with the publication of The Nature of the Chemical Bond, one of the most-cited texts in science history.

By then, at age thirty-eight, Pauling was a full professor; head of the chemistry division at Caltech; the youngest person ever elected to membership in the National Academy of Sciences; and father of three sons and a daughter.

In the mid-1930s Pauling took his research in a new direction. The Rockefeller Foundation at that time was directing significant funding toward defining the molecules essential to life. Lured by Rockefeller support, Pauling turned his attention to the structure of biomolecules, especially proteins such as hemoglobin and antibodies. These were gigantic structural problems, molecule orders of magnitude more complex than any Pauling had worked with before. But again his hard work, deep understanding of simpler chemical structures, and model-building approach brought him success. Over the next fifteen years he made important discoveries about hemoglobin, including tracking the cause of sickle-cell anemia to changes of a few atoms among many thousands. Pauling also studied antibodies, producing the most sophisticated work at the time regarding the structural relationship between antibody and antigen. In addition, he investigated enzymes and other proteins. The capstone of this work was the publication in May 1951 of seven papers detailing the structures of a number of proteins at the level of individual atoms.

Pauling developed the powerful idea that biological specificity (the precise matching of antibody and antigen, for example, or the ability of an enzyme to react with only one substrate) was due to complementarity, in which the shape of one molecule precisely fits another like a key in a lock. This structural insight was critical to the development of molecular biology. For his achievements in structural chemistry Pauling was awarded the 1954 Nobel Prize in Chemistry.

By then, however, Pauling’s maverick temperament had made him well known for something other than science. At the urging of his wife, he began focusing on stopping the development and spread of atomic weapons. Many scientists shared Pauling’s antinuclear sentiments, but few were as outspoken or perseverant. A proponent of world government and democratic socialism, Pauling had no qualms about attacking U.S. government policies he deemed wrong. Federal authorities responded by putting him under FBI surveillance, canceling research grants, refusing him a passport, and stripping him of his security clearance. Senator Joseph McCarthy accused him of being a communist, and the press smeared Pauling; still, he carried on.

By the late 1950s Pauling was a world leader in the peace movement. In 1957 and 1958 he and his wife gathered the signatures of some 11,000 scientists on a global petition to end nuclear weapons testing and presented it to the United Nations. He was finally rewarded: the day after the first nuclear test ban treaty went into effect on 10 October 1963, Pauling learned that he had won the Nobel Peace Prize. Instead of warm public support following the award, however, Pauling encountered criticism. The New York Herald-Tribune dubbed him a “placarding peacenik,” and Life magazine called the prize “a weird insult from Norway.” Many observers felt that President John F. Kennedy should have won the award instead.

During his years of political activism, Pauling’s science foundered. Following a failed attempt to find a structure for deoxyribonucleic acid (DNA), he moved his research increasingly toward the study of what he termed “molecular medicine.” Pauling believed that the body could be viewed as an array of chemical reactions. Optimal health, in his view, could thus be achieved if the reaction conditions were right and the proper molecules present in the proper amounts. He spent years trying to find a molecular basis for mental disease, ways to counter inborn metabolic conditions, and a theory of anesthesia. But here Pauling’s theories outstripped the technology of the time: the complexity and subtlety of biochemical systems in living organisms required more sophisticated analytical tools than had yet been invented. Each of his lines of investigation, while promising, refused to yield definitive results. His only significant scientific success during this period was a theory, developed with Emile Zuckerkandl, outlining how tracking the differences in similar biomolecules (such as hemoglobins) between various species could be used as a clock to time evolutionary divergence. The “molecular clock” idea has since proven important for evolutionary biology.

His Caltech colleagues in the late 1950s began grumbling about Pauling’s fruitless pursuit of medical findings instead of basic chemistry. The president of Caltech and a number of trustees were concerned about his reputation as a left-wing agitator. As a result, in the late 1950s Pauling lost the chairmanship of the Caltech chemistry division, along with a good deal of his laboratory space. It was an insult he never forgot. One week after winning the Nobel Peace Prize, Pauling announced that he was leaving Caltech.

He spent the next decade as an academic nomad, working at various think tanks and universities, never finding a suitable intellectual home. Pauling spent much of the 1960s working on unifying ideas, including a system of ethics based upon science, as well as a book on the molecular basis of civilization, but nothing was published.

In the late 1960s Pauling became interested in the health effects of a single vitamin, ascorbic acid or vitamin C, which some evidence indicated had beneficial effects on everything from the common cold to cancer, but his controversial and widely publicized claims were strongly criticized by the medical community. There is no doubt that his work helped change the nutritional habits of millions of people, and a growing body of evidence in later years underscored the importance of high doses of vitamins, including C, in promoting health. In 1973 Pauling cofounded a California research institute devoted to the study of the health effects of vitamin and other nutrients. There he conducted research until his death from cancer at age ninety-three. He had long outlived Ava Helen, who died thirteen years earlier, on 7 December 1981.

Pauling had a substantial effect on the history of science. Modern chemistry owes a great deal to his ability to explain chemistry in quantum mechanical terms, and to successfully apply his strongly structural approach to the form and function of complex organic and inorganic molecules. Pauling’s insights about the importance of complementarity between giant molecules as a basis for biological specificity became an important approach for the new field of molecular biology—a field in which Pauling can be rightly considered a founding father.

Using his scientific fame as a springboard for political activism, Pauling became an important figure in the worldwide peace movement of the 1950s. His perseverance in the face of persecution was admirable; his rallying of scientific opinion against atmospheric nuclear testing was critical in achieving public sentiment in favor of a test ban. But perhaps history will judge Pauling most kindly for his character rather than his deeds. Especially in the current era of bland, poll-based, middle-of-the-road politics, Pauling’s maverick outspokenness and willingness to risk his career for what he thought to be right appears increasingly admirable.

Pauling’s personal and scientific papers are available in the Oregon State University Special Collections in Corvallis, Oregon. Additional Pauling-related material is available in the archives of the California Institute of Technology. Several overviews of his life are available, including Thomas Hager, Force of Nature: The Life of Linus Pauling (1995) and Linus Pauling and the Chemistry of Life (1998); and Ted and Ben Goertzel, Linus Pauling: A Life in Science and Politics (1995). Also useful is Barbara Marinacci, ed., Linus Pauling in His Own Words (1995). Obituaries are in the Los Angeles Times (20 Aug. 1994), New York Times (21 Aug. 1994), and Chicago Tribune (28 Aug. 1994).

Thomas Hager