Albert Francis Birch

Albert Francis Birch

Albert Francis Birch , called Francis Birch , (born August 22, 1903 in Washington, DC , † January 30, 1992 in Cambridge , Massachusetts ) was an American geophysicist . Birch was the Sturgis Hooper Professor of Geology at Harvard University from 1949 to 1974.

Life

Birch graduated from Harvard University with a bachelor's degree in electrical engineering in 1924 (magna cum laude). He then worked for two years as an electrical engineer for the New York Telephone Company before he decided to study physics. From 1926 to 1928 he studied in Strasbourg with Pierre-Ernest Weiss and then at the high-pressure laboratory of Percy W. Bridgman at Harvard. He was an instructor in physics from 1930 to 1932, received his master’s degree in 1929, and received his doctorate in 1932. Soon after, he was leading the high pressure research in geophysics at Harvard. During World War II he took part in the Manhattan Project and was then back at Harvard, where he became Sturgis Hooper Professor of Geology in 1949. He was at times head of the Faculty of Earth Sciences. In 1974 he retired, but continued researching until his death.

He married Barbara Channing and had three children with her.

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He became known through experimental research into the properties of minerals under high temperatures and pressures, such as those found in the interior of the earth . In 1952 he published a well-known article in the Journal of Geophysical Research , in which he demonstrated that the earth's mantle is mainly composed of silicate minerals, the upper and lower earth mantle are separated by a thin layer in which a phase transition of silicate minerals takes place and that the inner and outer cores of the earth are alloys of crystalline and molten iron . However, the part of this paper best known among geophysicists is a footnote that he included in the introduction:

“Careless readers should be warned that normal language will transition to a letterpress form when applied to the interior of the earth. Some examples of correspondence follow: "

Letterpress form	Usual meaning
For sure	Doubtful
Undoubtedly	Maybe
Sure proof	Vague suggestion
Not refutable argument	Trivial contradiction
Pure iron	Unsafe mixture of all elements

In 1947 he adapted Murnaghan's isothermal equation of state , which was designed for infinitesimal deformation , to Euler's finite deformation and developed the formula known today as the Birch-Murnaghan equation of state .

In 1961 Birch published two papers on the speed of compression waves , in which he was able to show a linear relationship (today called "Birch's Law") between the speed of compression waves V _p in rocks and minerals and their atomic weight and density : ${\displaystyle {\bar {M}}}$ ${\displaystyle \rho }$

${\displaystyle V_{p}=a({\bar {M}})+b\rho }$.

He also researched the heat flow from the interior of the earth.

During World War II, Birch was given the task of constructing the Little Boy atomic bomb . On August 5, 1945 on Tinian he supervised the installation of the separately delivered uranium in the bomb housing, the preparation for use and the loading into the Enola Gay aircraft . He instructed the aircraft crew how to unlock the bomb. On August 6, 1945 it was dropped on the Japanese city of Hiroshima .

Memberships and honors

He was President of the Geological Society of America in 1963/64 and received numerous honors in his career, including the Arthur L. Day Medal (1950) and Penrose Medal (1969) from the Geological Society of America, the William Bowie Medal from the American Geophysical Union (1960), the National Medal of Science (1967), the Vetlesen Prize (1968) (with Sir Edward C. Bullard ), the Gold Medal from the Royal Astronomical Society (1973) and the Bridgman Award (1983) from the International Association for the Advancement of High Pressure Research. Since 1992, the American Geophysical Union has funded the Francis Birch Lecture , a lecture given by a well-known researcher in this field during the annual meeting, in its Department of Physical Tectonics . He was an honorary doctor from the Universities of Chicago and Harvard. He received the Legion of Merit of the US Navy for work on the Manhattan Project.

In 1941 Birch became a Fellow of the American Physical Society . In 1942 he was elected to the American Academy of Arts and Sciences . Since 1950 he was a member of the National Academy of Sciences and since 1955 of the American Philosophical Society .

Fonts

• Elasticity and the constitution of the earth's interior , Journal of Geophysical Research, Volume 57, 1952, pp. 227-286
• Heat from radioactivity , in H. Faul, Nuclear Radioactivity, Wiley 1954, pp. 148-174
• with Robert F. Roy, Edward R. Decker, David D. Blackwell: Heat Flow in the United States , Journal of Geophysical Research, Volume 73, 1968, pp. 5207-5221
• Speculations on the earth's thermal history , Geolog. Soc. America Bulletin, Vol. 76, 1965, pp. 133-154
• Composition of the earth's mantle , Geophys. J., Volume 4, 1961, pp. 295-311
• Geophysical applications of high pressure research , in: William Paul, Douglas Warschauer, Solids under Pressure, McGraw Hill 1963, pp. 137-162
• Density and composition of mantle and core , Journal of Geophysical Research, Volume 69, 1964, pp. 4377-4388

Web links

Commons : Albert Francis Birch  - collection of images, videos and audio files

• Thomas J. Ahrens: Albert Francis Birch - August 22, 1903 – January 30, 1992 . Birch's biography at the National Academy of Sciences
• Kenneth H. Olsen: Francis Birch (1903-1992). Birch's biography at the American Geophysical Union
• Obituary for Birch. New York Times online, February 5, 1992; accessed March 25, 2009 . 

Individual evidence

1. ^ Elasticity and constitution of the Earth's interior. In: Journal of Geophysical Research . Volume 57, pp. 227-286, 1952.
2. ↑ Finite elastic strain of cubic crystals. In: Physical Review . Volume 71, pp. 809-824, 1947
3. ↑ The velocity of compressional waves in rocks to 10 kilobars. Part 2. In: Journal of Geophysysical Research . Volume 66, pp. 2199-2224, 1961
4. ^ Composition of the Earth's mantle. In: Geophysical Journal of the Royal Astronomical Society . Volume 4, pp. 295-311, 1961
5. ↑ Memoir of Francis Birch by Thomas J. Ahrens ( Memento from April 14, 2012 in the Internet Archive ) (PDF; 114 kB), Harvard Faculty of Arts and Sciences
6. ^ Members of the American Academy. Listed by election year, 1900-1949 ( PDF ). Retrieved September 29, 2015
7. ^ Member Directory: Francis Birch. National Academy of Sciences, accessed December 9, 2015 . 
8. ^ Member History: A. Francis Birch. American Philosophical Society, accessed May 2, 2018 .