Force of Nature- The Life of Linus Pauling

by Thomas Hager

  Because of his self-funding and personal control over the laboratory's administration, Noyes's Research Laboratory of Physical Chemistry was allowed to develop differently from MIT, which maintained a distinctly practical approach to the education of engineers. Noyes was, of course, convinced that his new ideas about training were best for the entire institute. During a two-year stint as acting president of MIT, he tried to convince the engineers, as he said in a later speech, that "industrial research is not the main research opportunity of educational institutions. . . . The main field for educational institutions is research in pure science itself—a study of fundamental principles and phenomena, without immediate reference to practical application." The MIT engineers were not impressed. Instead, they saw his little kingdom siphoning funds from the school's main purpose—the teaching of engineering—and distracting their students.

  At the same time, the research laboratory's very success was undermining it. Other institutions, eager to emulate the Noyes model, began raiding his faculty and snapping up his best graduates. The worst blow came in 1912 when Berkeley—after first approaching and being turned down by Noyes—lured away one of his star faculty members, G. N. Lewis, by promising him his own program. Lewis jumpstarted his California chemistry division by taking with him another of Noyes's top professors and some of the best graduate students. Other professors and fellows from the MIT program were given offers they couldn't refuse from private industry and better-funded colleges. Chronically underfunded, MIT couldn't compete.

  Compared to the quality of the Berkeley offer, it was almost laughable when his former MIT student, George Ellery Hale, asked Noyes in 1909 to give up MIT to come to an unknown, underfunded school called Throop, even with Hale's extravagant promises of future support from all the rich fellows he knew. But by 1915, concerned about the increasingly industrial attitude at MIT and tempted by Hale's evermore concrete assurances of new facilities, Noyes was ready to rethink the offer and agreed to visit Throop. In 1917, Hale's promises became reality with the dedication of a new building he had convinced a wealthy family to fund, the Gates Laboratory of Chemistry, and Noyes began spending three months during the winter in Pasadena. But he couldn't bring himself to cut his East Coast bonds entirely, to leave his home, his sailing, the lab he had built.

  He would have to be kicked out. Back at MIT, Noyes's annual absences further annoyed an administration already irked by his laboratory's independence. A showdown developed between Noyes and the engineers, and the engineers won. In 1919 the president of MIT asked Noyes to withdraw from an active role in the chemistry department. Within months, at age fifty-three, Noyes resigned his post, gave up the research laboratory—"the embodiment of my love and devotion," he called it—ended the period of thirty years he had dedicated to MIT, and headed west.

  In Pasadena, King Arthur was once again treated like royalty. The Gates Laboratory of Chemistry was a much larger facility than his MIT lab, and he was presented with a $200,000 fund for research, arranged by lumber magnate and Throop board chairman Arthur Fleming. The ecstatic Hale even gave Noyes his used Cadillac, a soon-to-become-legendary touring car the students called Old Mossie (short for Demosthenes, in honor of its pronounced stutter). Old Mossie, said to hold the world's record for the standing broad jump because Noyes so often tried to start off in high gear, replaced the Research as a vehicle for weekend trips with favorite students and colleagues, the destination now camping spots in the desert or his beach house at Corona del Mar instead of the bays and islands around Boston.

  Noyes immediately started putting into effect the vision of higher education in the sciences that he had been denied at MIT. "Noyes not only originated most of the educational policies that made Caltech what it is, but he formulated them so carefully that they have served almost without change," wrote Noyes's colleague and early Caltech physics professor Earnest Watson. These policies included an insistence on small size, with a select and limited undergraduate student body; a concentration on doing a few things very well rather than becoming a broad-based university; a commitment to creative research at all levels, even undergraduate; an insistence on giving undergraduates a strong education in the humanities as well as the sciences; and an emphasis on basic rather than applied science. Noyes didn't stop there. His interest in students led him to foster a system for their self-government and to help plan their living arrangements, to provide for close contact between students and professors both academically and socially. He also supported the decision to make Caltech the first all-male institution of higher education—apart from military academies—west of the Hudson; he would have no coeds on campus to distract his budding scientists. For the chemistry division itself, Noyes adopted some elements of the German model for scientific institutes—such as an emphasis on discussing cutting-edge research in small seminars rather than large lecture classes—but purposefully rejected others, especially the German penchant for building institutes around a central charismatic researcher. Noyes believed in the primacy of the group over the individual; he was a consummate team player.

  Caltech was to be a new kind of school, a monastery dedicated to research, an experimental laboratory for Noyes's theories on the creation of scientists—an institution, it was later said, for geniuses.

  X-rays

  And Linus Pauling was a test case.

  Noyes called Pauling into his office in Gates at the beginning of the new term to have an introductory chat. They had corresponded throughout the previous spring and summer. Noyes had written first, asking about Pauling's background, especially in physical chemistry; Pauling wrote back about his disappointment in the one class he had taken at OAC. Noyes knew the author of the text Pauling had used and didn't think the book was worth much. He sent both Pauling and Paul Emmett proof sheets of the first nine chapters of a new physical chemistry text he was cowriting and asked them, in addition to reading the chapters, to solve the problems posed at the end. Instead of the standard approach, asking students to apply previously memorized equations to specific cases, Noyes's problems guided students toward deriving the equations themselves. His stress on making students think rather than memorize, giving them approaches to answers rather than the answers themselves, was a key element in his educational strategy. Once students had been forced to puzzle through a reasoning process, Noyes believed, the concepts they learned would stay with them. In the summer weekends and evenings after inspecting pavement all day on the Oregon coast, Pauling worked through all five hundred problems. "I learned a great deal about physical chemistry during the three months of the summer," Pauling remembered. Noyes's emphasis on logical and precise thinking and his technique of guiding students to discover laws and principles by themselves, Pauling wrote, "had an important effect on my own thinking about science." Noyes, for his part, was impressed by the Oregon boy's ability for independent work.

  Through their correspondence Noyes also learned of Pauling's early collection of minerals and later fascination with Lewis's and Langmuir's work on chemical bonds. Extrapolating from those interests, Noyes decided that Pauling should do his doctoral research at Caltech in the laboratory of Roscoe Dickinson, a young professor who was using a new x-ray device to study the structure of crystals. At his suggestion Pauling read a book about this new technique during the summer. The process was called x-ray crystallography and involved shooting a beam of x-rays at a crystal, then figuring out from the way the rays were scattered how the crystal was structured. The concept seemed simple to Pauling, the math wasn't too difficult, and the technique could pin down bond lengths and angles—the distance between the atoms in crystals and their orientation to one another. "I'm reading X-rays and Crystal Analysis," Pauling wrote Paul Emmett that summer, "but not learning much. Interesting, tho. . . ."

  Pauling didn't realize then that Noyes was preparing him for something special.

  What distinguishes graduate from undergraduate training in the physical sciences was—and is—the expectation that graduate student
s will discover something new in the laboratory. At OAC, Pauling had done well in his course-related laboratory work. But like most under graduates, he spent almost all his time in the lab learning basics: how to measure, weigh, purify, and test chemicals, repeating others' experiments rather than designing his own. He wasn't expected to find anything original, although at OAC he made one unsuccessful stab at it: During his senior year, he tried crystallizing iron in a magnetic field, hoping to learn something about the magnetic properties of atomic iron by examining the orientation of the crystals—an interesting idea, using visible crystals as a way to "see" into the invisible world of atoms. Working under the supervision of his metallography professor, he successfully deposited iron crystals on a bar of copper. But when he tried to polish them for examination under a microscope, the crystals rubbed off.

  Original laboratory work required a different set of skills from those that had made Pauling a classroom prodigy. Instead of memorization and intellectual flash, it called for patience, precision, and manual dexterity, along with a knack of recognizing practical approaches to solving problems. In order to develop these skills graduate students are placed with a mentor, a major professor, under whose tutelage and in whose laboratory they are introduced to the mysteries surrounding a particular problem and are given tools with which to solve those mysteries. It is a master-apprentice relationship in which the goal is to become another master, one capable of finding out new things about nature and teaching new apprentices.

  The decision about which major professor to work with is critical, and Roscoe Gilkey Dickinson was a good choice for Pauling. Dickinson was a favorite former MIT student of Noyes's who had followed his mentor to California in 1917 and earned his Ph.D. in chemistry—the first ever granted by Caltech—just two years before Pauling arrived. He was only ten years older than Pauling, close enough in age to take on the role of an older brother, and the two of them quickly became friends. The small size of Caltech at the time helped—during his first year, Pauling was Dickinson's only graduate student. Within a few weeks of the start of the first term, Dickinson and his wife were having Pauling over for dinner and taking him (and, later, Ava Helen as well) on overnight camping trips into the desert.

  In the laboratory they were complementary types: Pauling effervescent with ideas, interested in almost everything, ready to go in ten directions at once; Dickinson focused, methodical, careful, "an especially clear-headed and thoughtful scientist," Pauling later wrote, "strongly critical of carelessness and superficiality." Dickinson did not have a penetrating theoretical intellect, but he would be, for Pauling, a needed counterweight, a logical, down-to-earth guide to the rigors of original laboratory research using the finicky, demanding, revolutionary technique of x-ray crystallography.

  - - -

  Most physicists had agreed for more than a century before Pauling entered graduate school that light existed as waves of energy. A simple way to demonstrate this is to shine a beam of light through a grating made of closely ruled slits, which breaks the light waves into smaller wavelets—the way an ocean wave behaves when hitting a seawall with holes in it. If the slits in the grating are the right distance apart (they have to be spaced correctly for the wavelength of light being used), the light will form a pattern on a screen on the other side, bright spots where the wavelets of light coming out of one slit combine in rhythm with those coming out of others, reinforcing the wave pattern, dark spots where the wavelets collide out of rhythm, canceling each other. This is a diffraction pattern. When the light is a combination of many wavelengths, like sunlight, diffraction can lead to strikingly beautiful effects: the iridescent blue of butterfly wings and the glow of mother-of-pearl. Pauling, although he didn't know the nomenclature, had wondered about this optical effect as early as age thirteen when, walking down a Portland street in the rain, he looked up and saw a rainbow pattern made by the arc of a streetlight shining through the crosshatched fabric of his umbrella. It would be several years before he learned in his first physics course that he had seen a diffraction pattern.

  After x-rays were discovered in 1895, most physicists supposed they were a special kind of light—you could, after all, take amazing photographs with them of nails inside wood or bones inside a hand—and thus would also behave like waves. But no one could be certain until it could be shown that x-rays exhibited some of the definitive properties of waves, such as diffraction. The problem was that the space between the slits of a grating in a diffraction experiment had to be about the same order of magnitude as the wavelength being studied. Fine gratings, about twenty thousand lines per inch, worked for visible light. But x-rays were much more energetic than light, which meant, according to classical physics, that their wavelength would be much shorter— perhaps one one-thousandth the size of visible light. It was impossible to make a grating that fine.

  The German physicist Max von Laue thought that if humans couldn't make a proper grating, nature might. Naturally occurring crystals were thought to be made of atoms arranged in regular patterns, in sheets a few atoms thick. It was Laue's belief that these atomic sheets were about the right size to act like the slits in a diffraction grating for x-rays. The pattern coming out the other side would be complicated, of course, because crystals were made up of atomic sheets in three dimensions; it would be like what one would get by stacking a number of gratings on top of each other. But there should still be a pattern. Laue's boss at the University of Munich, Arnold Sommerfeld, thought the idea was preposterous and tried to convince him not to waste time on it. But in 1912 two students confirmed Laue's prediction by firing a beam of x-rays at a crystal of zinc sulfide and capturing the scatter on a photographic plate, creating what would later be called a Laue photograph. When the plate was developed, there was a circular pattern of light and dark spots—a diffraction pattern. Laue had proved that x-rays behaved like waves. Nature magazine termed his finding "one of the greatest and most far-reaching discoveries of our own age." Two years later, it won him the Nobel Prize.

  The discovery was important for two reasons. First, by showing that x-rays behaved like waves, it allowed scientists to determine their size and build instruments to distinguish among various wavelengths. (X-rays come in a range of wavelengths, just like visible light.) But the second field of research pioneered by Laue turned out to be even more fruitful. Once they had a beam of a specific wavelength, researchers could use x-rays to study the spacing of the crystal gratings: X-ray crystallography became the first probe for "seeing" the three-dimensional structure of matter at the atomic level.

  - - -

  One of the fathers of chemistry, Sir Humphrey Davy, noted a century before Pauling came to Caltech that "nothing tends so much to the advancement of knowledge as the application of a new instrument. The native intellectual powers of men in different times are not so much the causes of the different success of their labours, as the peculiar nature of the means and artificial resources in their possession." X-ray crystallography proved to be an artificial resource of immense potential.

  The theory behind it was simple. The researcher worked with three factors, x-rays of a certain wavelength, a crystal grating of a certain structure, and the diffraction pattern—which were linked in a straightforward mathematical relationship. Knowing the pattern and one of the two other factors, the third could be solved. Much of the early mathematics and practical technique were worked out by a British father-son team of physicists, Sir Henry and Lawrence Bragg, who made their laboratories in Cambridge and Manchester the world's foremost centers of x-ray crystallographic research.

  In theory it was simple, but in practice the piecing together of crystal structures was slow, tedious, and hobbled by the complexity of the diffraction patterns. The equipment in the early days was homemade and suffered from variable quality. Crystals generally had to be unusually large, carefully prepared, cut at specific angles, and precisely positioned to get a good pattern. If you got successful Laue photographs, you had to painstakingly measure the pos
ition and intensity of scores of spots. Then came the mathematical transformations. Even with simple crystals, each structure required months of work in precomputer days. And if the crystal was too complex, if it contained more than a dozen or so atoms in the basic, repeating unit of structure called the unit cell, it would scatter the x-rays in a pattern too complex to decipher. The whole process was something like trying to puzzle out the shape of a piece of ornate wrought iron by shooting it with a homemade shotgun and analyzing the ricochet patterns.

  For all these reasons it was limited to very simple crystals. But when it worked it was amazing. For the first time researchers had a tool that allowed them to understand the arrangements of individual atoms in crystals, to measure precisely the distances and angles between them. The first crystal structure the Braggs solved was rock salt, and it was a surprise. The crystal was one gigantic latticework, each sodium ion surrounded by six equidistant chlorides, each chloride by six equidistant sodiums. There were no discernible individual "molecules" of sodium chloride. The finding shook the field of theoretical chemistry, leading immediately to new ideas about how salts behaved in solution. Another early success in the Bragg lab was the discovery of the structure of diamond, pure carbon with its atoms linked, as earlier chemists had theorized, to form three-sided pyramids called tetrahedra. The Braggs went on to solve a number of other crystals (and would themselves share a Nobel the year after Laue).