Harold Irving "Doc" Ewen (March 5, 1922 – October 8, 2015) was an American physicist, radio astronomer, and business executive. He served in the United States Navy in World War II as a second lieutenant. As a graduate student under Edward M. Purcell, he was the first to detect the galactic 21-cm hydrogen line.
Harold Irving Ewen | |
|---|---|
| Born | March 5, 1922 |
| Died | October 8, 2015 (aged 93) |
| Education | Ph.D. (1951) |
| Alma mater | Harvard University |
| Known for | Detection of 21-cm hydrogen line |
| Spouse | Mary Ann Whitney[1] |
| Children | Donald, Bruce, Mark, Deborah, David, Daniel, and Rebecca[1] |
| Parents | |
| Awards | IEEE Morris E. Leeds Award (1970) Beatrice M. Tinsley Prize (1988) |
| Scientific career | |
| Thesis | Radiation from Galactic Hydrogen at 1420 Megacycles per Second (1951) |
| Doctoral advisor | Edward M. Purcell |
Biography
editEwen was born on March 5, 1922, in Chicopee, Massachusetts,[3] son of S. Arthur Ewen and Ruth F. Fay. After an education at the Technical High School in Springfield, Massachusetts,[2] he matriculated at Amherst College, studying undergraduate mathematics and astronomy,[1] and was awarded a B.A. in 1943.[3] With World War II underway, he joined the Navy.[1] Initially, he taught celestial navigation at Amherst as part of a pilot training program. Ewen received training in electronics and radar technology at Princeton University and MIT,[4] then joined Navy airborne squadron 112, based in England, as a radar officer with the rank of Second Lieutenant.[5][6][7]
Following the war, Ewen began graduate studies at Harvard on the G.I. Bill,[7] pursuing a degree in physics. He participated in the development of the 95-inch Harvard Cyclotron.[4] Edward M. Purcell suggested that Ewen study prior work on the hyperfine line of neutral hydrogen. As a naval reserve officer, Ewen was able to obtain a translation of a 1945 paper by the Dutch astronomer H. C. van de Hulst on the subject. Van de Hulst expressed pessimism that such a signal would be detectable. Nonetheless, Ewen and Purcell agreed that his thesis topic should be to construct a microwave spectrometer to find a lower limit on the detectability of the 21-cm hydrogen line.[6]
With a $500 grant from the AAA&S, Ewen was able to purchase components to construct a pyramidal horn antenna and a 21-cm receiver. With the instrument assembled, a galactic 21-cm signal was successfully detected on March 25, 1951.[6] This unexpected result was soon confirmed by Dutch and Australian astronomers.[8] Ewen was able to defend his thesis in May of that year, and he was awarded a Ph.D. from Harvard. He joined the Harvard Business School to pursue an MBA.[6]
Career
editIn the fall of 1951, Ewen was called up to serve in the Korean War.[5] He remained for a month before negotiating his return to civilian life.[6] He joined with Bart Bok as directors of the newly founded Harvard radio astronomy program during 1952–1958,[9] creating the nation's first Ph.D. program in this new field. During the 1950s, Ewen was involved in the planning for a national radio astronomy facility, and the site search for what would eventually become the Green Bank Telescope observatory.[4]
Ewen joined with his friend Geoff Knight to launch the Ewen Knight Corporation in 1952, which was established to construct a hydrogen line receiver for Harvard at the Agassiz Station. This company became a major supplier of equipment for radio observatories, including the NRAO.[6] In 1956 he was married to Mary Ann Whitney;[10] the couple would have seven children.[1] Ewen was elected to the American Academy of Arts and Sciences in 1957.[11] He founded the Ewen Dae Corporation in 1958,[3] whose name was a play on [k]night and day and also became the initials of the couple's first child.[6][10]
Ewen devised a sextant-like radio direction finder that was used on submarines to find the position before firing missiles.[6] During 1989-1992 he was executive vice president at the Millitech Corporation, becoming vice president for special projects, 1993–2000. He served as president of E.K. Associates starting in 1992.[4] In 2001, he became a research professor at the University of Massachusetts. Following his retirement, on November 12, 2002, Ewen gave the inaugural Gordon Lecture at the Arecibo Observatory.[9] He was the technical operations director of Special Projects LLC in 2004.[4]
In 1970, Ewen was given the IEEE Morris E. Leeds Award "for contributions to the design of sensitive radiometric systems, and for the codiscovery of the 21-cm spectral line of interstellar hydrogen".[12] Ewen and Purcell were awarded the Beatrice M. Tinsley Prize in 1988 for the "first detection of 21-cm hyperfine transition radiation of neutral hydrogen".[13] The horn antenna used to detect the galaxy's 21-cm line from Harvard is now a historical marker.[14]
References
edit- ^ a b c d e Ewen, Daniel, Harold I. Ewen, International Astronomical Union, retrieved 2023-05-01.
- ^ a b c Amherst College Biographical Record, 1951: Biographical Record of the Graduates and Non-graduates of the Classes of 1878-1950 Inclusive, Trustees of Amherst College, November 3, 2009, p. 499.
- ^ a b c The Ewen-Purcell Horn at Green Bank, Green Bank, NRAO, retrieved 2023-05-01.
- ^ a b c d e Bouton, Ellen N.; Kellerman, Kenneth (December 1, 2015), ""Doc" Harold Irving Ewen (1922–2015)", Bulletin of the American Astronomical Society, 47: 11, Bibcode:2015BAAS...47..011B, retrieved 2023-05-01.
- ^ a b Stephan, Karl D. (January 28, 1998), "Harold Ewen", Oral History Interviews, retrieved 2023-05-01.
- ^ a b c d e f g h Kellermann, Kenneth I.; et al. (June 29, 2020), Open Skies: The National Radio Astronomy Observatory and Its Impact on US Radio Astronomy, Springer International Publishing, pp. 35–75, doi:10.1007/978-3-030-32345-5_2, ISBN 9783030323455, S2CID 226691573.
- ^ a b Lang, Kenneth R. (2018), A Brief History Of Astronomy And Astrophysics, World Scientific Publishing Company, p. 214, ISBN 9789813233850.
- ^ Ewen, H. I.; Purcell, E. M. (September 1951), "Observation of a Line in the Galactic Radio Spectrum: Radiation from Galactic Hydrogen at 1,420 Mc./sec.", Nature, 168 (4270): 356, Bibcode:1951Natur.168..356E, doi:10.1038/168356a0, S2CID 27595927.
- ^ a b Brand, David (October 24, 2002), "Space radio pioneer Harold Ewen to give inaugural Arecibo lecture", Cornell Chronicle, Cornell University, retrieved 2023-05-01.
- ^ a b Sullivan III, Woodruff T., Interview with Harold "Doc" Irving Ewen, National Radio Astronomy Observatory, retrieved 2023-05-01.
- ^ List of Members by Classes August 1, 1992, Records of the Academy (American Academy of Arts and Sciences), American Academy of Arts & Sciences, 1991, p. 101, JSTOR 3785923.
- ^ "IEEE Elects Officers And Presents Awards", Physics Today, 23 (2): 97, February 1970, doi:10.1063/1.3021998, retrieved 2023-05-01.
- ^ "Ewen and Purcell win Tinsley Prize", Physics Today, 42 (4): 92–94, April 1989, doi:10.1063/1.2810988, retrieved 2023-04-29.
- ^ "Ewen-Purcell Horn Antenna", The Historical Marker Database, retrieved 2023-05-01.
Further reading
edit- Harold "Doc" Irving Ewen, Boston Globe, October 22, 2015, retrieved 2023-05-01.
- "Dr. Harold Irving Ewen", American Academy of Arts and Science, 9 February 2023, retrieved 2023-05-01.