William Markowitz
Encyclopedia
) was an American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
astronomer
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...
, principally known for his work on the standardization
Standardization
Standardization is the process of developing and implementing technical standards.The goals of standardization can be to help with independence of single suppliers , compatibility, interoperability, safety, repeatability, or quality....
of time
Time
Time is a part of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify rates of change such as the motions of objects....
.
His mother was visiting Melč, Vítkov
Vítkov (Opava District)
Vítkov is a town in the Moravian-Silesian Region of the Czech Republic. It has circa 6,200 inhabitants.Villages Jelenice, Klokočov, Nové Těchanovice, Podhradí, Prostřední Dvůr, Lhotka and Zálužné are administrative districts of Vítkov....
in Austrian Silesia
Austrian Silesia
Austrian Silesia , officially the Duchy of Upper and Lower Silesia was an autonomous region of the Kingdom of Bohemia and the Austrian Empire, from 1867 a Cisleithanian crown land of Austria-Hungary...
(now :cs:Melč, Czech Republic) when William was born. The Polish family emigrated to the U.S.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
in 1910 and settled in Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...
.
William earned his doctorate from the university
University of Chicago
The University of Chicago is a private research university in Chicago, Illinois, USA. It was founded by the American Baptist Education Society with a donation from oil magnate and philanthropist John D. Rockefeller and incorporated in 1890...
in 1931, under W.D. MacMillan. He taught at Pennsylvania State College before joining the United States Naval Observatory
United States Naval Observatory
The United States Naval Observatory is one of the oldest scientific agencies in the United States, with a primary mission to produce Positioning, Navigation, and Timing for the U.S. Navy and the U.S. Department of Defense...
in 1936, working under Paul Sollenberger and Gerald Clemence in the time service department.
After having married Rosalyn Shulemson in 1943, Markowitz eventually became director of the department. He developed the ephemeris time
Ephemeris time
The term ephemeris time can in principle refer to time in connection with any astronomical ephemeris. In practice it has been used more specifically to refer to:...
scale, which had been adopted by the IAU
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...
in 1952 on a proposal formulated by Clemence in 1948, as an international time standard. He subsequently worked with Louis Essen
Louis Essen
Louis Essen FRS O.B.E. was an English physicist whose most notable achievements were in the precise measurement of time and the determination of the speed of light...
in England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
to calibrate
Calibration
Calibration is a comparison between measurements – one of known magnitude or correctness made or set with one device and another measurement made in as similar a way as possible with a second device....
the newly developed atomic clock
Atomic clock
An atomic clock is a clock that uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element...
s in terms of the ephemeris second. The fundamental frequency of caesium
Caesium
Caesium or cesium is the chemical element with the symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a melting point of 28 °C , which makes it one of only five elemental metals that are liquid at room temperature...
atomic clocks, which they determined as 9,192,631,770 +/- 20 Hz
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
, was used to define the second
Second
The second is a unit of measurement of time, and is the International System of Units base unit of time. It may be measured using a clock....
internationally since 1967. At the International Astronomical Union
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...
(IAU) meeting in Dublin in 1955, he had proposed the system of distinguishing between variants of Universal Time
Universal Time
Universal Time is a time scale based on the rotation of the Earth. It is a modern continuation of Greenwich Mean Time , i.e., the mean solar time on the Prime Meridian at Greenwich, and GMT is sometimes used loosely as a synonym for UTC...
, as UT0 (UT as directly observed), UT1 (reduced to invariable meridian by correcting to remove effect of polar motion) and UT2 (further corrected to remove (extrapolated) seasonal variation in earth rotation rate), a system which remains in some use 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
International Union of Geodesy and Geophysics
The International Union of Geodesy and Geophysics is a non-governmental organisation dedicated to the scientific study of the Earth using geophysical and geodesic techniques. The IUGG was established in 1919. Some areas within its scope are environmental preservation, reduction of the effects of...
, the American Geophysical Union
American Geophysical Union
The American Geophysical Union is a nonprofit organization of geophysicists, consisting of over 50,000 members from over 135 countries. AGU's activities are focused on the organization and dissemination of scientific information in the interdisciplinary and international field of geophysics...
, and the International Consultative Committee for the Definition of the Second.
After retirement in 1966, Markowitz served as professor of physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
at Marquette University
Marquette University
Marquette University is a private, coeducational, Jesuit, Roman Catholic university located in Milwaukee, Wisconsin. Founded by the Society of Jesus in 1881, the school is one of 28 member institutions of the Association of Jesuit Colleges and Universities...
until 1972, and also held a post at Nova Southeastern University
Nova Southeastern University
Nova Southeastern University, commonly referred to as NSU or Nova, is a private, coeducational, nonsectarian, research university located in Broward County, Florida, with its main campus in the town of Davie...
.