Mark Gordon Inghram (November 13, 1919 – September 29, 2003) was an American

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

. Inghram was a member of the

National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, NGO, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the ...

Life

Inghram was born in

Livingston Livingston or Livingstonemay refer to: Businesses * Livingston Energy Flight, an Italian airline (2003–2010) * Livingston Compagnia Aerea, an Italian airline (2011–2014), also known as Livingston Airline * Livingston International, a North Am ...

Montana Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, an ...

. He did undergraduate work at

Olivet College The University of Olivet, formerly known as Olivet College, is a private Christian college in Olivet, Michigan, United States. The college is accredited by the Higher Learning Commission. It was founded in 1844 by missionaries from Oberlin Coll ...

, receiving a

B.A. A Bachelor of Arts (abbreviated B.A., BA, A.B. or AB; from the Latin ', ', or ') is the holder of a bachelor's degree awarded for an undergraduate program in the liberal arts, or, in some cases, other disciplines. A Bachelor of Arts degree ...

in 1939. He worked in the

Manhattan Project The Manhattan Project was a research and development program undertaken during World War II to produce the first nuclear weapons. It was led by the United States in collaboration with the United Kingdom and Canada. From 1942 to 1946, the ...

during

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

and at Argonne National Laboratories from 1945 to 1947. He received his

Ph.D. A Doctor of Philosophy (PhD, DPhil; or ) is a terminal degree that usually denotes the highest level of academic achievement in a given discipline and is awarded following a course of graduate study and original research. The name of the deg ...

from the

University of Chicago The University of Chicago (UChicago, Chicago, or UChi) is a Private university, private research university in Chicago, Illinois, United States. Its main campus is in the Hyde Park, Chicago, Hyde Park neighborhood on Chicago's South Side, Chic ...

in 1947. He began teaching at the

as an instructor in 1947 and remained there until his retirement in 1985. He died at his home in

Holland Holland is a geographical regionG. Geerts & H. Heestermans, 1981, ''Groot Woordenboek der Nederlandse Taal. Deel I'', Van Dale Lexicografie, Utrecht, p 1105 and former provinces of the Netherlands, province on the western coast of the Netherland ...

Michigan Michigan ( ) is a peninsular U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, Upper Midwestern United States. It shares water and land boundaries with Minnesota to the northwest, Wisconsin to the west, ...

in 2003.Mark G. Inghram, Physicist, 1919-2003, helped establish age of the Earth
press release, University of Chicago News Office, October 2, 2003. Accessed on line October 29, 2007.Mark Inghram, Physicist
''Saint Paul Pioneer Press'', October 4, 2003.

Age of the Earth

Together with

Clair Patterson Clair Cameron Patterson (June 2, 1922 – December 5, 1995) was an American geochemist. Born in Mitchellville, Iowa, Patterson graduated from Grinnell College. He later received his Ph.D. from the University of Chicago and spent his entire pro ...

and George Tilton, Inghram was one of the first scientists to combine measurements on meteorites and the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

to find the

age of the Earth The age of Earth is estimated to be 4.54 ± 0.05 billion years. This age may represent the age of Earth's accretion (astrophysics), accretion, or Internal structure of Earth, core formation, or of the material from which Earth formed. This dating ...

. Over time, the decay of

uranium Uranium is a chemical element; it has chemical symbol, symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Ura ...

lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...

will change the isotopic makeup of terrestrial lead. Patterson, Tilton and Inghram assumed that iron meteorites, which contain lead but virtually no uranium, formed at the same time as the Earth. Assuming this to be true, the isotopic makeup of lead in iron meteorites should still be the same as that of the newly formed Earth, so the Earth can be dated by comparing the composition of lead in iron meteorites with that in new volcanic material on the Earth. Patterson, Tilton and Inghram did this and found that the Earth was approximately 4.5 billion years old.Concentration of Uranium and Lead and the Isotopic Composition of Lead in Meteoritic Material
C. Patterson, H. Brown, G. Tilton, and M. Inghram, ''Physical Review'' 92, #5 (December 1953), pp. 1234–1235. DO
10.1103/PhysRev.92.1234

References

{{DEFAULTSORT:Inghram, Mark 1919 births 2003 deaths 20th-century American physicists University of Chicago alumni Members of the United States National Academy of Sciences Mass spectrometrists Olivet College alumni Manhattan Project people Physicists from Montana