Obituaries
Hans W. Liepmann
1914 – 2009
Hans Wolfgang Liepmann was known for his wit and infectious enthusiasm that inspired generations of students. As a leading researcher in fluid mechanics, Liepmann was the Theodore von Kármán Professor of Aeronautics, Emeritus, and was the third director of Caltech’s Graduate Aeronautical Laboratories (GALCIT) from 1972 to 1985. He died on June 24, 2009, at the age of 94.
“When all is said and done, his greatest contribution to Caltech and to the scientific area was the enthusiasm he brought to his work, the confidence he gave younger folks convincing them how important they were and what their work meant in the context of the aeronautical world,” said Frank Marble, the Hayman Professor of Mechanical Engineering and Professor of Jet Propulsion, Emeritus, in his oral history. At Liepmann’s memorial, held on January 23, 2010, John Cummings (BS ’69, MS ’70, PhD ’73) recalled his experience as a sophomore in a thermodynamics course taught by Liepmann: “Hans gave us a test and none of us did very well. And instead of coming back and being frustrated with us, Hans said, ‘I haven’t taught you well. Let’s try again.’ I just can’t imagine another Caltech professor ever saying something like that.” When it came to publishing, Liepmann didn’t care to have his name attached to every paper, Cummings said. “Hans didn’t have a big ego,” he recounted. “He wouldn’t allow me to list him as a coauthor on two publications from my thesis work . . . It was, as he said, my work, not his—very different from many professors.”
In his own oral history, Liepmann explained why he always emphasized teaching. “I consider teaching more important,” he said. “That’s really our main goal in life, if we take the professorship seriously. And also, I think, it has the more lasting influence. Whether you like it or not, most of your startling papers are going to be footnotes in handbooks in the not-too-distant future, and that goes for everybody. . . . But the teaching, the passing on of a certain style and approach to science, and also to knowledge, in a sense; that is, in my opinion, a more challenging and also more rewarding business.”
Liepmann genuinely cared for his students, always taking the time to talk to each of them and entertain everyone when he threw parties at his big white house overlooking the Rose Bowl. “If there was one thing I remembered about Hans besides being a great teacher, it was his ability to host a party,” Cummings said. Years later, after Cummings graduated from Caltech, he would return with his wife and spend time with Liepmann, who always welcomed them with coffee and snacks.
He was always an advocate for the students, and they invited him to be Caltech’s commencement speaker in 1982. “I think the undergraduates are really mistreated here,” he said in his oral history. “I’m amazed that they don’t make more noise, because they are overloaded. . . . They are always behind, always overworked, and then you get this famous burn-out; they suddenly want to take a leave. I do not think we should cater only to the best-prepared and brightest guys, but take into account the possibly deeper, but certainly slower-moving ones.”
Born in 1914 in Berlin, Liepmann grew up during World War I. His father was a physician and his grandfather was a professor of surgery, and because of family tradition, he was put into a classical school, where he was forced to study Greek and Latin—even though he had decided early on that he wanted to study science. “I had a terribly tough time in school,” he said. “I only kept going because I always thought, ‘Boy, when I get out of here! I have to get out, I have to go to the university, and then I will do physics.’”
Just a month after Hitler came to power, his family left Germany in 1933 for Istanbul. There, Liepmann got his wish and studied physics, mathematics, astronomy, and mechanics. After graduate studies at the University of Zürich, he came to Caltech in 1939 to work with Theodore von Kármán, who recruited him after he, having downed a few too many beers at his PhD party, inexplicably blurted out that he wanted to study “hydrodynamics.” Up until that party, he never drank, he said.
Liepmann hardly spoke English when he first came to the United States, which he initially tried to avoid because of its reputation as a country filled with “very rich people, very poor people, and gangsters.” Of course, he discovered that “it was pure nonsense,” and he soon mastered the language, although his distinctive accent stuck, becoming an endearing quality to those around him. “They loved his very strong Berlin accent,” said Donald Cohen, Powell Professor of Applied Mathematics, Emeritus. “They loved it so much that they mimicked it. Hans knew it, but he didn’t mind.”
Friends and colleagues fondly remembered his endless string of anecdotes and his wit. Colleague Robert Liebeck told one story that took place at the cafeteria, where Bill Se–ars (PhD ’38) turned a blind corner and almost bumped into Liepmann, who was carrying a tray. “My God, I almost hit you,” Sears said. Without missing a beat, Liepmann answered, “I told you not to call me that in public.” According to Von Kármán Professor of Aeronautics, Emeritus, Anatol Roshko (MS ’47, PhD ’52), he was also known for his penchant for “the friendly insult, of which he was a master.”
Roshko added that he was never politically correct. “He disliked bombast and self-importance, and here his agility with a polite insult often came in handy.”
Liepmann inspired and encouraged generations of students, but his message to the class of 1982 is applicable to us all: “Remember that there is an outside world to see and enjoy. Add a fourth dimension: to know, to understand, to do—and to dream.” —MW
