Kenneth Leon Nordtvedt is an American physicist. He was born on April 16, 1939, in

Chicago (''City in a Garden''); I Will , image_map = , map_caption = Interactive Map of Chicago , coordinates = , coordinates_footnotes = , subdivision_type = Country , subdivision_name ...

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolita ...

. Nordtvedt graduated from the

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the ...

(1960) and

Stanford University Stanford University, officially Leland Stanford Junior University, is a private research university in Stanford, California. The campus occupies , among the largest in the United States, and enrolls over 17,000 students. Stanford is consider ...

(Ph.D., 1964) and was a junior fellow in the

Harvard Society of Fellows The Society of Fellows is a group of scholars selected at the beginnings of their careers by Harvard University for their potential to advance academic wisdom, upon whom are bestowed distinctive opportunities to foster their individual and intell ...

(1963–1965). Soon after witnessing the Sputnik spacecraft cross the Boston sky in fall of 1957, he became a part-time student employee for the Mars Probe project at the MIT Instrumentation Lab, and in early 1960s was staff physicist at the same Laboratory's project to develop the Apollo Mission's navigation and guidance system.

Works

Theories of gravity

In 1968 Nordtvedt calculated how and to what degree the gravitational-to-inertial mass ratio of gravitationally compact bodies—bodies with significant gravitational binding energy—will generally differ from one in gravity theories other than

general relativity General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics ...

, and he then showed how lunar laser ranging data could be used to measure that key ratio to significant precision for the Earth. He was a board member and scientific advisor overseeing the joint NASA-ESA Space Test of Equivalence Principle mission. In 1986 he was appointed by then President

Ronald Reagan Ronald Wilson Reagan ( ; February 6, 1911June 5, 2004) was an American politician, actor, and union leader who served as the 40th president of the United States from 1981 to 1989. He also served as the 33rd governor of California from 1967 ...

to the

National Science Board The National Science Board (NSB) of the United States establishes the policies of the National Science Foundation (NSF) within the framework of applicable national policies set forth by the President and the Congress. The NSB also serves as an ind ...

. He showed in 1988 that General Relativity's

gravitomagnetism Gravitoelectromagnetism, abbreviated GEM, refers to a set of formal analogies between the equations for electromagnetism and relativistic gravitation; specifically: between Maxwell's field equations and an approximation, valid under certain ...

between Earth and Moon, as those bodies orbit the Sun, was essential to fitting the synodic month and half synodic month range signals from lunar laser ranging. He had support from

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

and

NSF NSF may stand for: Political organizations *National Socialist Front, a Swedish National Socialist party *NS-Frauenschaft, the women's wing of the former German Nazi party *National Students Federation, a leftist Pakistani students' political gr ...

for much of his research, as well as being a

Sloan Fellow The Sloan Fellows program is the world's first mid-career and senior career master's degree in general management and leadership. It was initially supported by a grant from Alfred P. Sloan, the late CEO of General Motors, to his alma mater, MIT ...

. His research was the subject of a ''

Wall Street Journal ''The Wall Street Journal'' is an American business-focused, international daily newspaper based in New York City, with international editions also available in Chinese and Japanese. The ''Journal'', along with its Asian editions, is published ...

'' article featured on the front page.

Tax policy

Nordtvedt was elected to three terms in the

Montana state legislature The Montana State Legislature is the state legislature of the U.S. state of Montana. It is composed of the 100-member Montana House of Representatives and the 50-member Montana Senate. The Montana Constitution dictates that the legislature mee ...

for a six-year period from 1979–1984, and there he wrote one of the first inflation indexing reforms of income tax law in the nation. He served briefly in 1989 as Director of the Montana Department of Revenue.

Genetic genealogy

Nordtvedt is also an active

genetic genealogist Genetic genealogy is the use of genealogical DNA tests, i.e., DNA profiling and DNA testing, in combination with traditional genealogical methods, to infer genetic relationships between individuals. This application of genetics came to be used b ...

theorist. He has done his own research into genetic

haplogroups A haplotype is a group of alleles in an organism that are inherited together from a single parent, and a haplogroup ( haploid from the el, ἁπλοῦς, ''haploûs'', "onefold, simple" and en, group) is a group of similar haplotypes that shar ...

, particularly the Y DNA group I, to which he belongs.More Realistic TMRCA Calculations Ken Nordtvedt Journal of Genetic Genealogy, Volume 4, Number 2, Fall, 2008, pp. 96–103.
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References

1968 "Equivalence Principle for Massive Bodies" Phys. Rev. 169, 1017 1968 "Testing Relativity with Laser Ranging to the Moon" Phys. Rev. 170, 1186 1960 "Interplanetary Navigation System Study" MIT Instrumentation Laboratory Report R-273 1964 "Preliminary Study of a Backup Manual Navigation Scheme" MIT Instrumentation Laboratory E-1540 {{DEFAULTSORT:Nordtvedt, Ken 1939 births 21st-century American physicists American geneticists American relativity theorists Fellows of the American Physical Society Living people Massachusetts Institute of Technology alumni Montana State University faculty Stanford University alumni Theoretical physicists

Works

Theories of gravity

Tax policy

Genetic genealogy

See also

References