Kenneth Leon Nordtvedt is an American physicist. Nordtvedt graduated from the

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a Private university, private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of moder ...

(1960) and

Stanford University Leland Stanford Junior University, commonly referred to as Stanford University, is a Private university, private research university in Stanford, California, United States. It was founded in 1885 by railroad magnate Leland Stanford (the eighth ...

(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 intellect ...

(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 as Einstein's theory of gravity, is the differential geometry, geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of grav ...

, 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, 1911 – June 5, 2004) was an American politician and actor who served as the 40th president of the United States from 1981 to 1989. He was a member of the Republican Party (United States), Republican Party a ...

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 of the United States, president and the United ...

. He showed in 1988 that General Relativity's gravitomagnetism 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 agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

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 g ...

for much of his research, as well as being a Sloan Fellow. His research was the subject of a ''

Wall Street Journal ''The Wall Street Journal'' (''WSJ''), also referred to simply as the ''Journal,'' is an American newspaper based in New York City. The newspaper provides extensive coverage of news, especially business and finance. It operates on a subscriptio ...

'' 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 ...

for a six-year period from 1979 to 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 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 , ''haploûs'', "onefold, simple" and ) is a group of similar haplotypes that share a common ancestor with a sing ...

, particularly the Y DNA group I, to which he belongs.

Selected works

* 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

References