Happy Birthday, Linus!

Today, 28 February, marks the birthday of a man whose life truly embodied the idea of scientific activism. In 1963, Linus Pauling (1901-1994) received the Nobel Peace Prize (officially the 1962 prize) for his tireless work on nuclear disarmament. Well before then, though, he had already established himself as one of the world’s foremost chemists by contributing to our understanding of chemical bonding and formulating valence bond theory. As a Renaissance man, of sorts, he had even gone on to apply his chemical knowledge to biology, elucidating fundamental structural aspects of proteins and discovering the molecular basis of sickle cell anemia, with all of these efforts contributing to his 1954 Nobel Prize in Chemistry.

Pauling, the only person ever awarded two unshared Nobel Prizes, was the recipient of the second of nine Nobel Prizes awarded to date at least partially for work against nuclear weapons. Only three of these nine were awarded to scientists. The 1985 Nobel Peace Prize went to the International Physicians for the Prevention of Nuclear War, and Joseph Rotblat (1908-2005) and the Pugwash Conferences on Science and World Affairs shared the 1995 Nobel Peace Prize for their efforts to eliminate nuclear weapons. The awarding of the 1962 prize to Pauling was a controversial move because Pauling had been particularly critical of Western nuclear proliferation. He received the prize a year late in 1963, and he only received it after a personal campaign launched by Gunnar Jahn (1883-1971), the chair of the committee.

Linus Pauling was born in Portland, Oregon, where he lived for most of his youth. After leaving high school in 1917 without a diploma, he entered Oregon Agricultural College as a chemical engineering major. He left college for a few months to work, but returned after being offered a job as a quantitative analysis instructor. He graduated in 1922 and entered graduate school at the California Institute of Technology (Caltech). Although Caltech was relatively new and unestablished at this point, it would be one of the most prominent scientific institutions in the world by the time Pauling left 40 years later. In graduate school, Pauling studied x-ray crystallography under Roscoe Dickinson, and in 1925 he received a Ph.D. in chemistry, with minors in physics and mathematics. After spending some time in Munich at the Institute of Theoretical Physics, Pauling returned to Caltech in 1927 as an assistant professor. He was promoted to associate professor in 1929 and full professor in 1931. From 1931 to 1933, he published a series of seminal papers in which he described the details of chemical bonding from the valence bond theory point of view.

Valence bond theory is a quantum mechanical description of chemical bonding, describing chemical bonds within a molecule individually, as an electron pair coming from the combination of two atomic orbitals. In this way it is intuitive—chemists tend to think of molecules as collections of smaller units, especially since that is how molecules are synthesized in the laboratory. Valence bond theory was initially published in 1927 by Walter Heitler (1904-1981) and Fritz London (1900-1954) with a paper on the H₂ molecule, but after Pauling published his first series of papers on the subject in the early 1930s, he became its chief advocate. Valence bond theory allowed chemists to use quantum mechanics without having to learn the detailed math behind it, and Pauling made valence bond theory attractive by introducing many shortcuts. Also, by applying the concept of resonance, he was able to account for the delocalization of electrons in some molecules, although this involved drawing multiple structures for a given molecule, something that was impractical for large molecules. Valence bond theory was successful primarily because it was simple, but this oversimplification eventually led to its downfall in favor of the more rigorous approach to chemical bonding found in molecular orbital theory. In 1939, Pauling published the Nature of the Chemical Bond, one of the most influential chemical textbooks ever written, having been cited over 16,000 times to date. By the time the third edition was published in 1960, though, Pauling had become largely irrelevant as a theoretical chemist, due to his willful ignorance of molecular orbital theory.

Since 1939, Pauling had gone on to solve biological problems, including the secondary structures of proteins and the molecular basis of sickle cell anemia. In a moment of pure scientific inspiration, Pauling inductively determined the three-dimensional geometry of the alpha-helix—one of the fundamental units of protein structure—while lying in bed sick in Oxford. He reported this finding, along with the structure of the beta-sheet—the other basic structure found in proteins—in 1951. Before publishing these results, though, he had already reported an idea that would revolutionize the fields of medicine and biology: the concept of the molecular disease. In 1949 Pauling and his co-authors described the molecular basis of sickle cell anemia, for the first time connecting the symptoms of a human medical condition to basic chemical principles. The idea of molecular medicine is only today finally coming into its own, even though it was first introduced by Pauling’s work over half a century ago.

After having solved so many fundamental chemical and biological problems, Pauling believed that these same techniques could be applied to social problems, especially war. Although he was not originally interested in such issues, his wife Ava Helen Miller introduced him to politics, which dominated much of his later life. Pauling began crusading against nuclear weapons in 1946 when he and seven other scientists formed the Emergency Committee of Atomic Scientists, chaired by Albert Einstein. Pauling approached political and social problems as a scientist, making it his goal to understand the effects of nuclear testing and to relay those findings to the public. His early efforts were to prevent the creation of the hydrogen bomb, but after its creation he focused on nuclear disarmament. In particular, he scientifically determined how fallout from nuclear testing would influence the rates of congenital deformities. In 1958 he presented a petition, signed by 9,235 scientists wishing to end nuclear testing, to the United Nations, and during the late 1950s and early 1960s, Pauling and his wife gave up to 100 lectures a year on the subject. Linus Pauling was awarded his Nobel Peace Prize in 1963, coinciding with the signing of the Nuclear Test Ban Treaty, which had at that point been signed by all relevant countries except China and France. The purpose of this treaty was to end above ground testing of nuclear weapons, and none of the participating countries have since tested a nuclear weapon above ground. Even France tested its last in 1974 and China in 1980.

Throughout history we have seen many phenomenal chemists, molecular biologists, medical scientists, and political activists. Rarely, though, has someone excelled in all of these areas, and probably none have to the extent that Linus Pauling did. Although his legacy was not always positive, including the mixed results of his advocacy of vitamin C, he made a lasting impact in all the areas he worked in, from founding the field of molecular medicine to helping curb Cold War nuclear weapon proliferation. His activism in particular was notable because not only did it involve scientific subjects, but he approached it in a scientific manner. Today, then, I wish to remember Linus Pauling as the premier scientific activist of the Twentieth Century. Let us hope that the memory of his legacy can spur socially conscious scientists into action throughout the next millennium.



Note: Much of the material in this post is derived from two essays I wrote for Dr. Anthony Stranges’ History of Science course at Texas A&M University during fall 2004: “Linus Pauling Versus Robert Mulliken” and “A Love/Hate Relationship: Scientific Activists and the Development of Nuclear Weapons”.