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Oct. 2, 2003 Press Contact: Steve Koppes
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Mark G. Inghram, Physicist, 1919-2003, helped establish age of the Earth

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Mark Inghram


University of Chicago physicist Mark G. Inghram, who was a member of the research team that determined the age of the Earth at 4.5 billion years, died Monday, Sept. 29, at his home in Holland, Mich., with Evelyn, his wife of 57 years, his family, and volunteers and staff of Hospice of Holland. He was 83.

Inghram and his colleagues were the first scientists to use meteorites to determine the age of the Earth. In the early 1950s, astronomers had suspected that the Earth was at least 4 billion years old, but no terrestrial materials had been found that were older than 2.5 billion years. Then, in 1953, Inghram and his colleagues showed that meteorites, which are approximately the same age as the Earth, were 4.5 billion years old. The feat earned him the J. Lawrence Smith Medal of the National Academy of Sciences in 1957.

Inghram also collaborated with the late Nobel laureate Willard Libby to determine the half-life of radioactive carbon-14. Libby then used the technique to develop radiocarbon dating, which is used to determine the age of organic materials.

“Inghram was a master experimentalist and an inventor and developer of mass spectrometers. These were his favorite shovels for excavating new areas,” said Gerald Wasserburg, Crafoord Laureate at the California Institute of Technology. “His instruments were the vehicles for which whole new fields of science were created and explored. Leaders of the new fields of cosmochemistry and geochemistry were trained in his laboratories under his rigorous guidance and mentorship. His methods and approaches and instrument designs governed the research approach in laboratories throughout the world.”

Mass spectrometry measures the abundances of different elements and different isotopes of elements-atoms of the same element with different masses. Using this technique he discovered more than a dozen naturally occurring and radioactive isotopes. His wife recalls him coming home each time he discovered a new isotope and celebrating with a dance. “He was a gifted dancer, graceful and light on his feet,” said his daughter, Cheryl Inghram.

Robert Gomer, the Carl William Eisendrath Distinguished Service Professor Emeritus in Chemistry at the University of Chicago, said Inghram pioneered in mass spectrometry. One major contribution was to develop an ion counting detector that proved important to the work of the atomic energy commission and in many scientific fields. “It increased the sensitivity of mass spectrometers by a factor of a million,” Gomer said.

In collaboration with William Chupka, professor emeritus of chemistry at Yale University, Inghram developed the technique of high temperature mass spectrometry.

“I think of Mark as one of the most gifted and energetic experimentalists I have ever known in my entire scientific life,” Chupka said. Together with Chupka, Inghram made it possible for the first time to identify and quantify the composition of atoms and molecules in high-temperature vapors.

“This technique was first applied to carbon vapor, resulting in the unambiguous determination of the heat of vaporization of the carbon atom from graphite. At the time, this quantity was a matter of much contention and importance since it was required for the determination of bond energies of all organic molecules,” Chupka said. “It has since been applied to other systems.”

Speaking on behalf of the family, son-in-law Nicholas Revill said that “his memory is honored by the achievements of those he taught, collaborated with and counseled.”

Inghram was born Nov. 13, 1919, in Livingston, Mont. He earned his B.A. from Olivet College in Michigan in 1939 and his Ph.D. from the University of Chicago in 1947.

He was a physicist in the Manhattan Project at Columbia University from 1942 to 1945, and a senior physicist at Argonne National Laboratory from 1945 to 1947. He began his long career at the University of Chicago as a physics instructor in 1947. He was appointed the Samuel Allison Distinguished Service Professor in Physics in 1969 and retired in 1985.

Inghram held several administrative positions at the University: Chairman of the Physics Department (1959-1970), acting Director of the Institute for the Study of Metals (1960-1961), Associate Dean of the Physical Sciences Division (1964-1971); Master of the Physical Sciences Collegiate Division (1981-1985); and Associate Dean of the undergraduate College (1981-1985). He also served on two committees of the National Academy of Sciences: Nuclear Geophysics (1953-1960), and Exploration of the Moon and Planets (1958-1961).

He was a member of the National Academy of Sciences, an honor that five of his former students also attained. Inghram also was a fellow of the American Academy of Arts and Letters, the American Physical Society and the American Association for the Advancement of Science. He received the University’s Llewellyn John and Harriet Manchester Quantrell Award for Excellence in Undergraduate Teaching in 1981.

Inghram is survived by his wife, Evelyn, and two children, Cheryl Inghram, Chicago, and Mark Inghram III, Eagle River, Alaska; two sisters, Martha Truesdell, Indianapolis, and Rebecca Schultheis, Minneapolis; and four grandchildren, Jared Inghram, Eagle River, Alaska; Jamie Zieba Spenser, Etna Green, Ind.; Maren Zieba, Seattle; and Joe Revill, Norwood, Middlesex, England.

A high-resolution image of Inghram is available at
Last modified at 02:48 PM CST on Saturday, October 04, 2003.

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