A Highly Fluid State

Robert Richardson becomes Tech's first alumnus to win the Nobel Prize

by Su Clauson-Wicker

Physicist Robert Richardson '58 remembers the spring he and his Cornell University colleagues discovered superfluid helium-3 -- the breakthrough for which they received the 1996 Nobel Prize in Physics in December -- as a time when he moved into his own highly fluid state.

"The race had been on for years to find the phase transition of solid helium-3. That spring when we knew we'd found liquid helium-3, we were making new discoveries every day," Richardson says. "We'd go home excited every night. I had trouble sleeping more than four hours and didn't take time to eat breakfast or lunch, but it didn't bother me. It was a big high for four or five months." That was 25 years ago.

At the Nobel ceremony in December, the Royal Swedish Academy of Sciences called the work of Richardson and his fellow researchers -- Cornell professor David Lee and Douglas Osheroff, now a Stanford professor -- "a breakthrough in low-temperature physics." Their prizewinning discovery of how helium-3 can transform itself into a liquid that flows without friction at temperatures near absolute zero changed rules of classical physics.

Ironically, the trio was actually trying to do something else when they made the epochal discovery. Lee had recruited Richardson to Cornell in 1966 for the express purpose of finding the point at which solid helium-3 becomes a nuclear magnet--its phase transition point. They were competing with labs around the country.

Richardson's goal was to cool helium down to two millikelvin or two-thousandths of a degree above absolute zero (-273.15 Celsius) to discover the phase transition in solid helium. They thought they'd found it late in 1971, but the squiggles in their data indicated something else -- that this was a liquid.

"It was confusing because we were cooling helium-3 by squeezing it at the melting pressure, converting liquid into solid. Some of it was liquid, and some was still solid," Richardson says.

The liquid helium-3 they found was not just a liquid but a superfluid -- it had no internal friction. You could direct a stream of a superfluid at a coin balanced on its side without toppling the coin because the superfluid exerts no force. When poured into a cup, the superfluid could run up the side and over the top, seemingly in defiance of gravity.

For a liquid to become superfluid, its atoms must be cooled to the point at which they all occupy the same quantum state (the point at which they are all linked together by interatomic forces; these weak forces are easily overcome when the atoms are active at higher temperatures). These linked atoms are pulled along by the group, encountering little resistance from obstacles. Superfluid helium-3 is also a superconductor -- its electrons flow without resistance.

"The superfluidity of helium-3 was totally unexpected," Richardson says. "During the 1960s, there was sort of a race between theory and experiment. Every time experimentation got to the temperature that theory predicted, theory advanced and pushed it to lower temperatures. The same month we made this discovery, an article in the Physical Review predicted that the phase transition would occur at a millionth of a degree above absolute zero, a thousand times colder than we could go."

Physicists had tinkered with superfluid helium since the late 1930s. The catch has been that scientists thought only helium-4 was involved. The odd number of nucleons in helium-3 atoms caused them to repel each other. For helium-3 to dance in a superfluid waltz, its nucleons must pair up so that the partners have an even number of nucleons between them.

The Cornell team not only found helium-3 pairing up in this manner, it showed that helium-3 does so in three distinct phases.

"We knew right away we had something big, really big," Richardson says, "The discovery was one of those things that few people are lucky enough to have happen. It's neat to do research looking at things nobody has looked at. It seems a bit like being an explorer."

As a Virginia Tech student in the 1950s, Richardson wasn't initially drawn to a physics major. The Arlington native started out wanting to be an electrical engineer, then a chemist. "But I was color blind, so I couldn't distinguish the endpoint in titrations [the endpoint occurs when the solution reacts and changes color]. When I complained to a professor, he told me I couldn't be a chemist without that ability, so I switched to physics," he says.

Richardson enjoyed physics, but he savored his electives just as much, especially a modern literature course and a calculus class taught by Alice "Ma" Pletta. "She was a fantastic teacher," he says. "And she must have taught four courses a quarter." (Teaching continues to be important to Richardson, and he has served on Virginia Tech's Physics Advisory Committee since 1989.)

Most of all, Richardson remembers learning human relations through the mandatory corps of cadets. "I learned leadership," he says. "I was assigned a roommate and placed in a squad with the other freshmen in my section of the alphabet. Through the experience, I learned how to interact easily with a variety of people. I didn't know it then, but this has been of tremendous value to me."

Richardson was regimental adjutant, probably the most time-consuming job in the corps, as well as head of the Pershing Rifles drill team (now the Gregory Guard) and an officer in several honorary societies.

"He was one of the guys who ran things on campus," says former roommate Bill Rakestraw (physics '59), also a Ph.D. scientist. "He was really bright and had a tremendous amount of energy. He could study just a bit and get a lot out of it."

Rakestraw remembers spending studying 10 hours for a physics exam to Richardson's five hours. "But he usually scored only about five points less than I did," he says. "In addition to all his other activities, Bob also managed to spend many hours playing bridge in the winter. It was crazy."

When he graduated in 1958, Richardson didn't feel he knew enough physics, so, at the encouragement of then physics chairman Marshall Hahn, he stayed another year to earn a master's degree. He went into the army as the commander of a unit repairing jeeps and tanks, took management courses, and jettisoned his plans for an MBA.

"It dawned on me that I didn't like the rigidity of management courses," he says. "I like the idea of being independent and having the opportunity to be creative. I like teaching. So I decided to go back to school for a Ph.D. in physics."

Richardson didn't think his grades were stellar enough to land him a place in a major research university, so he shopped around for a school with an interesting sub-field. He picked Duke for its low-temperature physics research.

The work at Cornell that earned Richardson the Nobel grew out of studies he started at Duke. "He was an outstanding student," Duke physics professor Horst Meyer remembers. Richardson impressed not only faculty members, but a fellow physics doctoral student, who became his wife. Betty Richardson also teaches on the Cornell faculty.

The helium-3 superfluid discovery was quickly embraced by the physics community, and awards began rolling in during the 1970s and 1980s. Richardson, now director of Cornell's Laboratory of Atomic and Solid State Physics, was elected a Fellow of the American Association for the Advancement of Science, a Guggenheim Fellow, and a Fellow of the American Physical Society. He also was elected to the National Academy of Sciences in 1986 and chaired its Physics Section from 1989 to 1992.

In addition to having implications for superconductivity, the superfluidity of helium-3 enabled scientists to study its particular form of magnetism and showed that nuclear magnetic resonance could work.

NMR, also known as magnetic resonance imaging, now is widespread in the medical diagnosis field. In recent years, cosmologists have hypothesized that liquid helium-3 may be the stuff of which cosmic strings are made. Cosmic strings are immense, hypothetical objects thought to play a role in galaxy formation.

The questions of what his discovery is good for and what he will do with his share of the $1.1 million prize have dogged Richardson since the public was notified of the prize in October.

"After we've split the prize, paid our taxes, and taken care of all kinds of related expenses (like traveling to Sweden), we'll each get about $150,000. I have some large debts from sending two daughters to college that I'm going to pay off. There won't be a lot more left," he says.

A jovial fellow with an easy smile, Richardson has been known to dress up in 19th-century garb and pretend to drink liquid nitrogen for a science presentation for Cornell alumni. "It's the ham in me," he says. But he is no stranger to sorrow, as indicated by his first reaction to the early morning call from the Nobel Committee:

"I was in a hotel room in Washington, D.C., attending a National Research Council committee meeting. I was terrified when the phone rang at 5:30 a.m.," he says. "My last early morning phone call had come on Nov. 20, 1994. The voice on the other end of that call identified himself as the emergency room doctor in Vanderbilt Hospital. He then told me that my daughter, Pamela, had just died. When the phone rang, I was certain that something must have happened to my wife Betty or my other daughter, Jennifer. It took thirty seconds before it finally dawned on me that he was talking about the Nobel Prize."

The Richardsons live outside of Ithaca, N.Y., in a rural area where one of their pastimes is trying to foil the deer that feed upon his 100 or more rhododendron bushes. To enlarge his collection, he has cut and grafted samples from around the world.

Richardson also enjoys baking up a few loaves of bread from scratch twice a week. Included in the process is using the "local beasties" instead of commercial yeast. He also tinkers in the darkroom, makes educational CD-roms about physics for fun, and enjoys the process of machining his own laboratory equipment.

"I am in a research field where everyone designs his own apparatus. All our graduate students in low-temperature physics here are taught to be inventors. They turn out to be good machinists, good plumbers. We have a great shop course here, a famous one," he says. "I learned how to use the lathe and the milling machine by just walking into the Virginia Tech machine shop and making things when I was a graduate student."

Another man who executed a major strike so early in his career might have been tempted to bask in that experience for the rest of his life. Not Richardson.

For the past 25 years, he continued to study a variety of problems in condensed matter at low temperatures, including metals, insulators, and liquid and solid helium. His lab has produced the lowest known temperatures ever achieved in the universe; it continues to hold that record for the western hemisphere. He still has the exhilarating sense of seeing things no one has ever seen before.

He looks youthful, lively, energized, when he pauses at his desk before returning to the lab. "Science is not all used up," he says.

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