William Coblentz

William Coblentz

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William Weber Coblentz (November 20, 1873 – September 15, 1962) was an American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...

 notable for his contributions to infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

 radiometry
Radiometry
In optics, radiometry is a set of techniques for measuring electromagnetic radiation, including visible light. Radiometric techniques characterize the distribution of the radiation's power in space, as opposed to photometric techniques, which characterize the light's interaction with the human eye...

 and spectroscopy
Spectroscopy
Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...

.

Early life, education, and employment


William Coblentz was born in North Lima, Ohio
North Lima, Ohio
North Lima is an unincorporated community in central Beaver Township, Mahoning County, Ohio, United States. Although it is unincorporated, it has a post office, with the ZIP code of 44452...

 to parents of German and Swiss descent. His mother (Catherine) died when Coblentz was just under three, leaving him temporarily with a family of just his younger brother (Oscar) and their father (David). However, the father remarried about 2 years later, and Coblentz appears to have admired his second mother (Amelia). Throughout Coblentz's childhood and adolescence, his family lived on farms, but apparently were never able to buy one of their own. The family's extremely modest circumstances led to a somewhat-delayed education for Coblentz, who did not finish high school (Youngstown, Ohio) until 1896, when he was 22 years old.

Coblentz entered the Case School of Applied Science, now Case Western Reserve University
Case Western Reserve University
Case Western Reserve University is a private research university located in Cleveland, Ohio, USA...

 in the fall of 1896, and received his Bachelor of Science degree in physics in June, 1900. He went on to earn MS (1901) and PhD (1903) degrees from Cornell University
Cornell University
Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...

 in Ithaca, New York, staying two years beyond his doctoral time by working as a Research Fellow with support from the Carnegie Institution. In the spring of 1905, Coblentz accepted a position with the newly-founded National Bureau of Standards (now the National Institute of Standards and Technology, NIST) in Washington, DC, where he spent his entire career. In 1905 he founded the Bureau's radiometry section, and headed it for 40 years until his retirement in 1945.

Scientific work


During the course of a long and productive career, Coblentz made many scientific contributions both of a pure and applied nature. Bibliographies of his work show that he had hundreds of scientific publications, talks, and abstracts to his credit. He received a total of ten patents during his lifetime, the first being US Patent 1,077,219 for a solar cell
Solar cell
A solar cell is a solid state electrical device that converts the energy of light directly into electricity by the photovoltaic effect....

 invention to convert sunlight to electricity.

Coblentz's first publication, "Some Optical Properties of Iodine", was based on his PhD research. On acquiring his doctorate, he soon began publishing regularly on problems related to infrared (IR) radiation, both those concerning spectroscopy
Spectroscopy
Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...

 and those concerning radiometry
Radiometry
In optics, radiometry is a set of techniques for measuring electromagnetic radiation, including visible light. Radiometric techniques characterize the distribution of the radiation's power in space, as opposed to photometric techniques, which characterize the light's interaction with the human eye...

. For example, Coblentz was among the first, if not the very first, to verify Planck's Law
Planck's law of black body radiation
In physics, Planck's law describes the amount of energy emitted by a black body in radiation of a certain wavelength . The law is named after Max Planck, who originally proposed it in 1900. The law was the first to accurately describe black body radiation, and resolved the ultraviolet catastrophe...

.

Infrared studies


When Coblentz entered Cornell University, infrared spectroscopy was in what today would be considered an extremely primitive state. As a young Cornell researcher, Coblentz assembled and calibrated his own IR equipment, and extended the range of IR measurements to longer wavelengths than had ever been reached. By 1905 he had acquired hundreds of spectra by tedious point-by-point measurements with a prism instrument of his own construction. These were published in 1905 with large fold-outs charts (not available in the later reprints), and tables of wavelengths at which various materials absorbed IR light. While such a massive spectral compilation itself was something of a tour de force, it is perhaps not the most important part of Coblentz's 1905 book. Instead, that honor probably goes to his generalization that certain molecular groupings, or functional groups in modern parlance, appeared to absorb specific and characteristic IR wavelengths. In time this would allow scientists to use a molecule's IR spectrum as a type of molecular fingerprint. This generalization had been hinted at in earlier work by others, but not with such a large amount of supporting data as Coblentz presented. Today, IR spectra are used in thousands of laboratories around the globe by scientists in many fields.

As an aside, Coblentz's early work on molecular spectra was not given the eager reception that hindsight might suggest. The reasons are numerous and have been explored by several authors.

Astronomical studies


Coblentz had a long interest in astronomical problems. In 1913, he developed thermopile detectors and used them at Lick Observatory to measure IR radiation from 110 star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...

s, and the planets Mars, Venus, and Jupiter. In this work he was assisted by Seth Nicholson, later of the Mt. Wilson Observatory. Extending this work, Coblentz and Carl Lampland, of the Lowell Observatory
Lowell Observatory
Lowell Observatory is an astronomical observatory in Flagstaff, Arizona. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark in 1965....

, measured large differences between the day and night temperatures on Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

, which implied a thin Martian atmosphere.

For his applications of IR detectors to astronomy, Coblentz is regarded as the founder of astronomical infrared spectroscopy
Infrared spectroscopy
Infrared spectroscopy is the spectroscopy that deals with the infrared region of the electromagnetic spectrum, that is light with a longer wavelength and lower frequency than visible light. It covers a range of techniques, mostly based on absorption spectroscopy. As with all spectroscopic...

. In recognition of his astronomical contributions, craters on the moon and Mars were named after him by 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...

.

Coblentz also made observations of solar eclipses, and published papers describing his work.

Other research


An inspection of Coblentz's bibliography shows that from about 1930 his research turned more toward measurements involving the ultraviolet (UV) region and away from infrared work. Much of this research had a distinctly bio-medical slant, such as his investigations of ultraviolet therapy (1938) and the production of skin cancer by UV exposure (1948).

Although Coblentz is remembered today mainly for his contributions to physics and astronomy, he also had interests in bioluminescence, atmospheric ozone, and, perhaps surprisingly, parapsychology. He appears to have brought the same energy to the latter field as he did to his other areas of interest.

Honors


The Coblentz Society, dedicated to the understanding and application of vibrational spectroscopy, is named in his honor, as is the Coblentz Medal. In addition, according to Meggers' biographical sketch, Coblentz was given membership card number 1 from the Society. Coblentz died just before his 1905 work on infrared spectroscopy was reprinted, nearly 60 years after its first publication.

Among the awards Coblentz received were the 1920 Janssen Medal
Janssen Medal (French Academy of Sciences)
The Janssen Medal is an astrophysics award presented by the French Academy of Sciences to those who have made advances in this area of science.The award was founded in 1886, though the first medal was not awarded until a year later...

 (French Academy of Sciences), the Rumford Medal of the American Academy of Arts and Sciences, and the Howard N. Potts Medal
Howard N. Potts Medal
The Howard N. Potts Medal was a science and engineering award presented by the Franklin Institute, of Philadelphia, Pennsylvania, USA.Also see The Franklin Institute Awards.-Laureates:Following people received the Howard N. Potts Medal:...

 of the Franklin Institute. In 1945, shortly after retiring, Coblentz received the Frederic Ives Medal by the OSA
Optical Society of America
The Optical Society is a scientific society dedicated to advancing the study of light—optics and photonics—in theory and application, by means of publishing, organizing conferences and exhibitions, partnership with industry, and education. The organization has members in more than 100 countries...

.

Coblentz also was elected a member of the National Academy of Sciences. He was awarded the Howard N. Potts Medal in 1910.

Family and personal life


In his autobiography, From the Life of a Researcher (1951), William Coblentz described his typical day as long hours of laboratory research followed by evenings spent on data analysis and writing papers. This left little time for socializing, and so it is not unexpected that Coblentz was over 50 before ever marrying. He wed Catherine Emma Cate of Vermont on June 10, 1924, and it is said that they spent their honeymoon in Flagstaff, Arizona while Coblentz was at the Lowell Observatory
Lowell Observatory
Lowell Observatory is an astronomical observatory in Flagstaff, Arizona. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark in 1965....

 measuring planetary temperatures. Catherine Cate Coblentz
Catherine Cate Coblentz
Catherine Cate Coblentz was an American writer, best known for her children's books in the 1930s and 1940s.- Life and work :...

 achieved success as a writer of children's book, worked for a time at the National Bureau of Standards, and was instrumental in raising money to build the Cleveland Park Neighborhood Library in Washington, DC.

William Coblentz reportedly was plagued by periods of poor health, but he lived nearly 90 years. He is buried in Rock Creek Cemetery
Rock Creek Cemetery
Rock Creek Cemetery — also Rock Creek Church Yard and Cemetery — is an cemetery with a natural rolling landscape located at Rock Creek Church Road, NW, and Webster Street, NW, off Hawaii Avenue, NE in Washington, D.C.'s Michigan Park neighborhood, near Washington's Petworth neighborhood...

 in Washington, DC alongside his wife and an infant daughter.

Further reading

  • A Physical Study of the Firefly, by William W. Coblentz, 1912
  • Man's Place in a Superphysical World, by William W. Coblentz, 1955 (concerning parapsychology)
  • Journal of the Optical Society of America, 1936, volume 36, number 2, pp. 61 – 71 (The presentation ceremony, and Coblentz's accompanying lecture, for the Ives Medal, along with a list of Coblentz's scientific publications.)
  • Applied Optics (November, 1963), commemorative issue with extensive material on Coblentz's scientific work


Copies of most of Coblentz's books are listed as being in the libraries of the University of Maryland and the American Institute of Physics, both in College Park, Maryland (USA), not far from where Coblentz lived, worked, and died.

External links