Robert Pound, 90

Robert Pound, 90, confirmed a key Einstein theory, dies

Robert Pound and a colleague confirmed a main prediction of the general theory of relativity.
Robert Pound and a colleague confirmed a main prediction of the general theory of relativity. (Paul Horowitz)
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By Martin Weil
Washington Post Staff Writer
Thursday, April 22, 2010

Robert Pound, 90, a Harvard University physicist who confirmed one of Albert Einstein's key theories and helped lay the groundwork for one of medicine's most powerful diagnostic tools, died of a heart ailment April 12 at a nursing home in Belmont, Mass.

At a time when scientists thought satellites and long distances might be required to confirm a main prediction of the general theory of relativity, Mr. Pound and a colleague did it indoors.

Carried out about 50 years ago at Harvard, the work helped validate Einstein by showing essentially that gravity could shift the frequency of light. It was notable for its precision and subtlety.

"People had presumed that Einstein was probably right" about the frequency shift, but it was extremely small and hard to measure, said Paul Horowitz, a Harvard professor of physics and electrical engineering. Yet, Horowitz said, Mr. Pound found a way to do it.

Radiation of a precise frequency was sent up and down an indoor shaft. A radiation source was mounted on a loudspeaker cone. Signals sent to the speaker caused tiny and carefully calibrated movements of the source, which had an important role in the experiment. The minuscule change in gravity over the shaft's height of about 70 feet also figured in calculations.

The work exhibited what Mr. Pound's son, John, described as his father's skill at "taking a theoretical concept and figuring out a way of translating it into some kind of elegant and easily measurable experiment."

Mr. Pound was also noted for fundamental work on nuclear magnetic resonance, or NMR, which became key in the creation of MRI (magnetic resonance imaging) devices that provide detailed images of bodily tissues.

Essentially, NMR involves the absorption of radio-frequency energy by the spin of a proton as it moves, like the tilted axis of a top, in a magnetic field.

Scientists thought that this absorption could be demonstrated in solids and liquids but were "clueless about what it took" to do it, Horowitz said.

NMR advances in the mid-1940s by Mr. Pound and colleagues E.M. Purcell and H.C. Torrey suggested ways in which variations in energy absorption could help show the positions of atoms in chemical compounds or human tissues.

Mr. Pound lacked the usual science credentials and did not hold a doctorate. The positions he achieved in the academic world reflected his intellectual ability and the fact that during the World War II era, when he began his career, scientific work was often conducted in secrecy and outside universities.

Robert Vivian Pound, whose father was a physicist and math professor, was born in Ridgeway, Ontario, on May 16, 1919. He moved with his family to Buffalo as a child and became a naturalized U.S. citizen.

After graduating from the University of Buffalo in 1941 with a degree in physics, he went into defense work. In 1945, he arrived at Harvard as a junior fellow. He became a professor and ultimately spent more than 50 years actively involved with the university. He received the National Medal of Science in 1990 for his pioneering experiments in NMR.

Besides his son, of San Rafael, Calif., Mr. Pound's survivors include his wife, the former Betty Andersen, who lives at the nursing home in Massachusetts, and two grandsons.

At the time of the relativity experiment, Mr. Pound taught by day and did lab work after hours.

He often returned home from his lab at daybreak but showed no weariness, his son said. Rather, there was "real palpable excitement," he said. "It was working."

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