Middle-of-night call signals new Nobel
Douglas Osheroff shares Nobel Prize in physics for the discovery of superfluidity in helium-3.
Two middle-of-the-night phone calls that came 25 years apart mark the high points of Douglas Osheroff’s scientific career.
On April 20, 1972, Osheroff was a slender, dark-haired graduate student with an intense gaze. Working with physicists David Lee and Robert Richardson in the ultra-low-temperature lab at Cornell University, he was exploring an unexpected behavior of helium-3, an uncommon isotope of the element helium.
At 2:40 that morning, Osheroff jotted a line in his lab notebook indicating that he and his advisers had found something extremely significant: the point at which helium-3 changes from an ordinary liquid into an extraordinary substance called a superfluid.
When it is a superfluid, a liquid moves without any resistance: It is arguably the closest thing to perpetual motion that occurs in nature.
Before that night, superfluidity had been discovered in only one other liquid, helium-4, though a number of other researchers had looked for this condition in helium-3 without success. Physicists had largely given up the search.
“I still get goose bumps just thinking about it,” recalls Osheroff, 51, now the J.G. Jackson and C.J. Wood Professor of Physics. “It was an exciting moment. There was absolutely nobody else in the entire building to share my discovery with. So I waited an hour, until I couldn’t stand it any longer, and then I called my advisers.”
The second portentous phone call came in direct consequence of that earlier morning discovery. On Oct. 9 of this year, Osheroff, who is still slender and intense, but whose hair is now frosted with gray, was jolted from his sleep at 2:30 a.m.
When the caller asked if he was Douglas Osheroff, “I told him, ‘Yes, this is Douglas Osheroff. Do you know that it’s 2:30 in the morning!'” The caller apologized but said he had a matter of “considerable urgency” to discuss. Osheroff’s first thought was of his mother, who is in frail health, but when the caller rattled off his name Carl Olof Jacobson and said he was calling from Stockholm, “I realized what was going on.”
The Royal Swedish Academy of Sciences was calling to inform him that he had been chosen to share this year’s Nobel Prize in physics with Richardson and Lee for their discovery of superfluidity in helium-3.
The initial discovery was an intensely private moment, shared with only colleagues and close friends. By contrast, the Nobel announcement thrust Osheroff immediately into the public spotlight, as he was inundated with calls from reporters around the world. Asked at a press conference that morning what it felt like to be a prizewinner he replied, “You don’t get any sleep and you spend all your time answering questions!”
Later in the day, several hundred colleagues attended an impromptu party outside the Varian physics building where Osheroff was lauded by department chair Blas Cabrera, President Gerhard Casper and Provost Condoleezza Rice.
The appeal of low-temperature physics
Superfluidity is unlike any familiar physical condition.
When helium is placed in a beaker and cooled to a temperature close to absolute zero, it changes into a substance that defies gravity by creeping up the walls and out of the container. If the container is spinning during the cooling process and then stopped, the superfluid will continue to spin as long as it is kept cold enough.
This strange behavior was one of the things that attracted Osheroff into low-temperature physics, after forays into electrical engineering and astrophysics during his undergraduate days at Caltech.
“I was drawn to the low-temperature work because it was so counter-intuitive. Who would expect a liquid to flow up and out of the top of a beaker?” he asked. In addition, he was intrigued by the sense of excitement in the low-temperature field at the time. In the 1970s, new refrigeration techniques were being developed that were steadily pushing temperatures down closer to the absolute limit. “There was a sense that there was a tremendous amount of new science to discover,” he said.
Osheroff’s journey toward those discoveries began in Aberdeen, a small logging town in Washington state, where he was born and raised, the second of five children. His father was a doctor and his mother was a nurse before she married.
“I think I was genetically predisposed to become a scientist,” Osheroff said. “As a child, I got into all kinds of things, many of which would get me into trouble with the FBI today!”
At 6, he was taking apart his toys to study the electric motors that powered them. At 10, playing with old telephone company equipment, he discovered that you could get quite an electric shock by hooking up a solenoid to a battery. He took his apparatus to school and had classmates lined up “20 deep” to set shocked experience. As a high school student he built a 100,000-volt X-ray machine out of secondhand parts.
He also turned the barrel of an old machine gun into a muzzle-loading rifle, which fired accidentally in the house. “My parents had a lot of patience with all the crazy things that I did,” he said.
Finishing high school, Osheroff applied to Stanford and the California Institute of Technology. He chose Caltech in large part because his older brother was enrolled at Stanford studying for a medical degree. “My brother was class valedictorian, as well as a good athlete, and I was tired of being compared to him.”
At Caltech he discovered his niche in low-temperature physics. After finishing his bachelor’s degree, he went on to Cornell for graduate study, where he met Phyllis Liu. A native of China who grew up in Taiwan, she was a graduate student in biochemistry. They began dating after she visited the physics laboratory to borrow some liquid nitrogen.
“I was very attracted to Phyllis, but I didn’t want to marry until I got my PhD and could support a wife,” Osheroff recalled. But she was finishing up her studies two years before he could complete his, and because she was in the United States on a student visa, she would be forced to return home once she got her degree. “So I proposed on her birthday, and we got married on Aug. 14, 1970.”
The prize-winning experiment
A year later, Osheroff began working on the experiment that ultimately led to the Nobel. The purpose of the experiment was to explore the magnetic properties of solid helium-3. To do this, he was using nuclear magnetic resonance (NMR), a technique that requires a very powerful magnet. The lab owned only one such magnet, and another group of graduate students also needed it for their experiment.
When the other students appropriated the magnet, Osheroff decided to keep his experiment cooled down and pass the time while he waited for its return running some simple experiments, primarily aimed at testing the cooling apparatus that he had designed and built.
He was testing a chamber that contained a mixture of liquid and solid helium-3, charting how the pressure in the cell varied as the liquid was converted to solid at a constant rate. Because the pressure is uniquely related to the temperature, this allowed him to measure the rate at which the helium-3 was cooling. “A lot of my fellow students thought I was wasting my time,” he said.
But just before Thanksgiving in 1971, he noticed a glitch in the graph: a point where the cooling rate suddenly slowed to one third its previous value. At first he thought it was a problem with the equipment. But when he repeated the experiment after Thanksgiving, starting with different proportions of solid and liquid, the change took place at precisely the same pressure.
“Then I knew we’d found something fundamental, I just didn’t know what,” he said.
Although they recognized that they had detected something real, the Cornell team’s first explanation was incorrect. They attributed it to a change in the solid helium-3 ice, rather than in the liquid. Nevertheless, their paper was accepted and published in the scientific journal Physical Review Letters without any problem.
But they were not satisfied with their explanation because it didn’t quite fit the observations. More studies using the NMR magnet showed that they had found a change in the liquid phase in other words, they had discovered superfluidity in helium-3.
Ironically, this explanation was initially rejected by the journal, and it took the intervention of some senior scientists in the field to get the discovery published.
“This prize just goes to show that you can make a mistake in physics, as long as you correct it yourself,” Osheroff said.
Years at Bell Laboratories
The discovery touched off a period of intensive research into the nature of this strange new substance. After getting his doctorate at Cornell, Osheroff moved to AT&T (now Lucent Technologies) Bell Laboratories where he played a major role in these investigations.
“We had a tremendous amount of fun,” recalled William Brinkman, now the senior vice president for physical science research at Bell Labs, who collaborated with Osheroff on a number of experiments.
“Doug has a fantastic green thumb in the laboratory. He has exceptional control of even the most complex experiments and can make them work,” said Brinkman, adding that this ability is particularly important in low- temperature physics, which is sometimes called slow-temperature physics because the experiments take such a long time to conduct.
Osheroff attributes his success as an experimentalist to his insecurity: “I want to know what is going on all the time. So I continually look for things that don’t seem to fit.”
According to Brinkman, one of the new Nobelist’s most amazing abilities is the way that he can recite extremely long poems, such as Edgar Allan Poe’s The Raven and Robert Service’s The Cremation of Sam McGee, entirely from memory. “It’s a measure of his mental ability that he can remember all those lines after downing several drinks,” he said. According to Osheroff, he began memorizing poetry before going to sleep in order to clear his mind of physics problems.
The 15 years at Bell Labs were some of the most enjoyable and productive in his life, Osheroff said. But his wife thought he would make a good teacher and urged him to take a job at a university. Finally, she was offered a job in the Bay Area by Genentech that he describes as “too good to turn down.”
Move to Stanford
With this impetus, the physicist began exploring the job prospects at Stanford and Berkeley. It turned out that William Fairbank, a prominent low temperature physicist, had just retired at Stanford and the department was looking for a replacement. Osheroff said he was particularly impressed by Stanford students, so he applied.
After arriving, he quickly discovered that he couldn’t spend as much time in the laboratory as he had at Bell Labs, where he took 95 percent of the data on his experiments himself. But he has found that working with students is a major compensation.
“I tell my students that they are like my children,” said Osheroff, who doesn’t have any of his own. “And Phyllis and I will come visit them when we’re old!”
According to Blas Cabrera, chairman of the physics department, “Doug invests an extraordinary amount of time and extracurricular effort on his students.” The results of all this effort were recognized in 1991 when he was awarded Stanford’s highest teaching award, the Walter J. Gores Award for Excellence in Teaching.
Osheroff spends much of his time instructing undergraduates. Now that he has received the Nobel he will “be able to continue Stanford’s tradition of having Nobel Prize winners teaching introductory courses,” Cabrera said.
The importance that Osheroff places on teaching is reflected in a promise that he made to himself and kept last Wednesday. He vowed that if he ever received a Nobel Prize and had a class scheduled that day he would teach the class. And he did.
In addition to the time he spends teaching, Osheroff has continued to study the intricacies of the helium-3 system. But he and his students also have turned their attention to the behavior of glassy materials at ultra-low temperatures. “Rather than looking at very clean, highly ordered systems, we are looking at very dirty, disordered systems,” he said.
Thirty years ago, scientists thought that various glassy materials would behave in much different ways when cooled to low temperatures. But they have found that materials as different as window glass and mylar exhibit some common characteristics, such as the variation of the speed of sound with temperature. These surprising features have made such materials a “very exciting” new subject, according to the physicist.
To Osheroff, these materials show that interesting science is always just waiting to be found: “In the latest Calvin and Hobbes book, Calvin says, ‘Treasure is everywhere.’ And treasure is physics.”