- William Markowitz
William Markowitz (
February 8 ,1907 inAustrian Empire -October 10 ,1998 inPompano Beach, Florida ) was an Americanastronomer , principally known for his work on thestandardization oftime .His mother was visiting
Meltsch über Troppau inAustrian Silesia (now , Czech Republic) when William was born. The Polish family emigrated to the U.S. in 1910 and settled inChicago .William earned his doctorate from the university in 1931, under
W.D. MacMillan . He taught atPennsylvania State College before joining theUnited States Naval Observatory in 1936, working underPaul Sollenberger andGerald Clemence in the time service department.After having merried Rosalyn Shulemson in 1943, Markowitz eventually became director of the department. He developed the
ephemeris time , which had been proposed bySimon Newcomb in the 19th century, as an international time standard. He subsequently worked withLouis Essen inEngland to calibrate the newly developedatomic clock s in terms of the ephemeris second. The fundamental frequency ofcaesium atomic clocks, which they determined as 9,192,631,770 Hz, was used to define thesecond internationally since 1967. At theInternational Astronomical Union (IAU) meeting inDublin in 1955 he had proposed the system which remains today.He served as President of the IAU commission on time from 1955 to 1961, and was active in the
International Union of Geodesy and Geophysics , theAmerican Geophysical Union , and theInternational Consultative Committee for the Definition of the Second .After retirement in 1966, Markowitz served as professor of
physics atMarquette University until 1972, and also held a post atNova Southeastern University .External links
* [http://ad.usno.navy.mil/wds/history/markowitz.html US Navy obituary]
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