Compton used X-rays to investigateferromagnetism, concluding that it was a result of the alignment ofelectron spins, and studiedcosmic rays, discovering that they were made principally of positively charged particles.
DuringWorld War II, Compton was a key figure in theManhattan Project that developed the firstnuclear weapons. His reports were important in launching the project. In 1942, he became a member of theExecutive Committee, and then head of the "X" projects overseeing the Metallurgical Laboratory, with responsibility for producingnuclear reactors to converturanium intoplutonium, finding ways to separate the plutonium from the uranium and to design an atomic bomb. Compton oversawEnrico Fermi's creation ofChicago Pile-1, the first nuclear reactor, which went critical on December 2, 1942. The Metallurgical Laboratory was also responsible for the design and operation of theX-10 Graphite Reactor atOak Ridge, Tennessee. Plutonium began being produced in theHanford Site reactors in 1945.
After the war, Compton became chancellor of Washington University in St. Louis. During his tenure, the university formally desegregated its undergraduate divisions, named its first female full professor, and enrolled a record number of students after wartime veterans returned to the United States.
Arthur Holly Compton was born on September 10, 1892, inWooster, Ohio, the son of Elias Compton and Otelia Catherine Augspurger,[2] who was named American Mother of the Year in 1939 and was of GermanMennonite descent.[3][4]They were an academic family. Elias was Dean of the University of Wooster (now theCollege of Wooster), which Arthur also attended. Arthur's eldest brother,Karl, who also attended Wooster, earned aPh.D. in physics fromPrinceton University in 1912, and was President of theMassachusetts Institute of Technology from 1930 to 1948. His second brother,Wilson, likewise attended Wooster, earned his Ph.D. in economics from Princeton in 1916 and was President of the State College of Washington (nowWashington State University) from 1944 to 1951.[5] All three brothers were members of theAlpha Tau Omega fraternity.[6]
Compton was initially interested in astronomy, and took a photograph ofHalley's Comet in 1910.[7] Around 1913, he described an experiment where an examination of the motion of water in a circular tube demonstrated the rotation of the earth, a device now known as theCompton generator.[8] That year, he graduated from Wooster with aB.S. and entered Princeton, where he received hisM.A. in 1914.[9] Compton then studied for his Ph.D. in physics under the supervision of Hereward L. Cooke, writing his thesis onThe Intensity of X-Ray Reflection, and the Distribution of the Electrons in Atoms.[10]
When Arthur Compton earned his Ph.D. in 1916, he, Karl, and Wilson became the first group of three brothers to earn PhDs from Princeton. Later, they would become the first such trio to simultaneously head American colleges.[5] Their sister, Mary, married a missionary, C. Herbert Rice, who became the Principal ofForman Christian College inLahore.[11] In June 1916, Compton married Betty Charity McCloskey, a Wooster classmate and fellow graduate.[11] They had two sons, Arthur Alan Compton andJohn Joseph Compton.[12]
For a time, Compton was a deacon at a Baptist church. "Science can have no quarrel", he said, "with a religion which postulates a God to whom men are as His children."[17]
In 1923, Compton published a paper in thePhysical Review that explained the X-ray shift by attributing particle-like momentum tophotons, something Einstein had invoked for his 1905 Nobel Prize–winning explanation of thephoto-electric effect. First postulated byMax Planck in 1900, these were conceptualized as elements of light "quantized" by containing a specific amount of energy depending only on the frequency of the light.[20] In his paper, Compton derived the mathematical relationship between the shift in wavelength and the scattering angle of the X-rays by assuming that each scattered X-ray photon interacted with only one electron. His paper concludes by reporting on experiments that verified his derived relation:
The quantityh⁄mec is known as theCompton wavelength of the electron; it is equal to2.43×10−12 m. The wavelength shiftλ′ −λ lies between zero (forθ = 0°) and twice the Compton wavelength of the electron (forθ = 180°).[21] He found that some X-rays experienced no wavelength shift despite being scattered through large angles; in each of these cases the photon failed to eject an electron. Thus the magnitude of the shift is related not to the Compton wavelength of the electron, but to the Compton wavelength of the entire atom, which can be upwards of 10,000 times smaller.[19]
"When I presented my results at a meeting of theAmerican Physical Society in 1923", Compton later recalled, "it initiated the most hotly contested scientific controversy that I have ever known."[22] The wave nature of light had been well demonstrated, and the idea that it could have a dual nature was not easily accepted. It was particularly telling that diffraction in a crystal lattice could only be explained with reference to its wave nature. It earned Compton theNobel Prize in Physics in 1927.[a] Compton and Alfred W. Simon developed the method for observing at the same instant individual scattered X-ray photons and therecoilelectrons. In Germany,Walther Bothe andHans Geiger independently developed a similar method.[18]
Compton at the University of Chicago in 1933 with graduate studentLuis Alvarez next to his cosmic ray telescope
In 1923, Compton moved to theUniversity of Chicago as Professor of Physics,[9] a position he would occupy for the next 22 years.[18] In 1925, he demonstrated that the scattering of 130,000-volt X-rays from the first sixteen elements in theperiodic table (hydrogen through sulfur) werepolarized, a result predicted by J. J. Thomson.William Duane fromHarvard University spearheaded an effort to prove that Compton's interpretation of the Compton effect was wrong. Duane carried out a series of experiments to disprove Compton, but instead found evidence that Compton was correct. In 1924, Duane conceded that this was the case.[18]
Compton investigated the effect of X-rays on the sodium and chlorine nuclei insalt. He used X-rays to investigateferromagnetism, concluding that it was a result of the alignment ofelectron spins.[24] In 1926, he became a consultant for the Lamp Department atGeneral Electric. In 1934, he returned to England as Eastman visiting professor atOxford University. While there, General Electric asked him to report on activities atGeneral Electric Company plc's research laboratory atWembley. Compton was intrigued by the possibilities of the research there intofluorescent lamps. His report prompted a research program in America that developed it.[25][26]
Compton's first book,X-Rays and Electrons, was published in 1926. In it he showed how to calculate the densities of diffracting materials from their X-ray diffraction patterns.[24] He revised his book with the help ofSamuel K. Allison to produceX-Rays in Theory and Experiment (1935). This work remained a standard reference for the next three decades.[27]
By the early 1930s, Compton had become interested incosmic rays. At the time, their existence was known but their origin and nature remained speculative. Their presence could be detected using a spherical "bomb" containing compressed air or argon gas and measuring its electrical conductivity. Trips to Europe, India, Mexico, Peru and Australia gave Compton the opportunity to measure cosmic rays at different altitudes and latitudes. Along with other groups who made observations around the globe, they found that cosmic rays were 15% more intense at the poles than at the equator. In September 1932, Compton attributed this to the effect of cosmic rays being made principally of charged particles, rather than photons asRobert Millikan had suggested, with the latitude effect being due toEarth's magnetic field. This resulted in a public altercation between Millikan and Compton in December. Ultimately, Compton was proven correct.[28][29][30]
Arthur Compton's ID badge from the Hanford Site. For security reasons he used a pseudonym.
In April 1941,Vannevar Bush, head of the wartimeNational Defense Research Committee (NDRC), created a special committee headed by Compton to report on the NDRC uranium program. Compton's report, which was submitted in May 1941, foresaw the prospects of developingradiological weapons,nuclear propulsion for ships, andnuclear weapons usinguranium-235 or the recently discoveredplutonium.[31] In October he wrote another report on the practicality of an atomic bomb. For this report, he worked withEnrico Fermi on calculations of thecritical mass of uranium-235, conservatively estimating it to be between 20 kilograms (44 lb) and 2 tonnes (2.0 long tons; 2.2 short tons). He also discussed the prospects foruranium enrichment withHarold Urey, spoke withEugene Wigner about how plutonium might be produced in anuclear reactor, and withRobert Serber about how the plutonium produced in a reactor might be separated from uranium. His report, submitted in November, stated that a bomb was feasible, although he was more conservative about its destructive power thanMark Oliphant and his British colleagues.[32]
The final draft of Compton's November report made no mention of using plutonium, but after discussing the latest research withErnest Lawrence, Compton became convinced that a plutonium bomb was also feasible. In December, Compton was placed in charge of the plutonium project.[33] He hoped to achieve a controlledchain reaction by January 1943, and to have a bomb by January 1945. To tackle the problem, he had the research groups working on plutonium and nuclear reactor design atColumbia University, Princeton University and theUniversity of California, Berkeley, concentrated together as theMetallurgical Laboratory in Chicago. Its objectives were to produce reactors to convert uranium to plutonium, to find ways to chemically separate the plutonium from the uranium, and to design and build anatomic bomb.[34]
In June 1942, theUnited States Army Corps of Engineers assumed control of the nuclear weapons program and Compton's Metallurgical Laboratory became part of the Manhattan Project.[35] That month, Compton gaveRobert Oppenheimer responsibility for bomb design.[36] It fell to Compton to decide which of the different types of reactor designs that the Metallurgical Laboratory scientists had devised should be pursued, even though a successful reactor had not yet been built.[37]
When labor disputes delayed construction of the Metallurgical Laboratory's new home in theArgonne Forest preserve, Compton decided to buildChicago Pile-1, the first nuclear reactor, under the stands atStagg Field.[38] Under Fermi's direction, it went critical on December 2, 1942.[39] Compton arranged forMallinckrodt to undertake the purification of uranium ore,[40] and withDuPont to build the plutonium semi-works atOak Ridge, Tennessee.[41]
Compton's house in Chicago, now a national landmark
Compton was at theHanford site in September 1944 to watch the first reactor being brought online. The first batch of uranium slugs was fed into Reactor B at Hanford in November 1944, and shipments of plutonium to Los Alamos began in February 1945.[42] Throughout the war, Compton would remain a prominent scientific adviser and administrator. In 1945, he served, along with Lawrence, Oppenheimer, and Fermi, on the Scientific Panel that recommended military use of the atomic bomb against Japan.[43] He was awarded theMedal for Merit for his services to the Manhattan Project.[44]
After the war ended, Compton resigned his chair as Charles H. Swift Distinguished Service Professor of Physics at the University of Chicago and returned to Washington University in St. Louis, where he was inaugurated as the university's ninth chancellor in 1946.[44] During Compton's time as chancellor, the university formally desegregated its undergraduate divisions in 1952, named its first female full professor, and enrolled record numbers of students as wartime veterans returned to the United States. His reputation and connections in national scientific circles allowed him to recruit many nationally renowned scientific researchers to the university. Despite Compton's accomplishments, he was criticized then, and subsequently by historians, for moving too slowly toward fullracial integration, making Washington University the last major institution of higher learning in St. Louis to open its doors toAfrican Americans.[45]
Compton retired as chancellor in 1954, but remained on the faculty as Distinguished Service Professor of Natural Philosophy until his retirement from the full-time faculty in 1961. In retirement he wroteAtomic Quest, a personal account of his role in the Manhattan Project, which was published in 1956.[44]
Compton was one of a handful of scientists and philosophers to propose a two-stage model offree will. Others includeWilliam James,Henri Poincaré,Karl Popper,Henry Margenau, andDaniel Dennett.[46] In 1931, Compton championed the idea of human freedom based onquantum indeterminacy, and invented the notion of amplification of microscopic quantum events to bringchance into the macroscopic world. In his somewhat bizarre mechanism, he imagined sticks of dynamite attached to his amplifier, anticipating theSchrödinger's cat paradox, which was published in 1935.[47]
Reacting to criticisms that his ideas made chance the direct cause of people's actions, Compton clarified the two-stage nature of his idea in anAtlantic Monthly article in 1955. First there is a range of random possible events, then one adds a determining factor in the act of choice.[48]
A set of known physical conditions is not adequate to specify precisely what a forthcoming event will be. These conditions, insofar as they can be known, define instead a range of possible events from among which some particular event will occur. When one exercises freedom, by his act of choice he is himself adding a factor not supplied by the physical conditions and is thus himself determining what will occur. That he does so is known only to the person himself. From the outside one can see in his act only the working of physical law. It is the inner knowledge that he is in fact doing what he intends to do that tells the actor himself that he is free.[48]
Compton was aPresbyterian.[49] His father Elias was an ordained Presbyterian minister.[49]
Compton lectured on a "Man's Place in God's World" atYale University,Western Theological Seminary and theUniversity of Michigan in 1934–35.[49] The lectures formed the basis of his bookThe Freedom of Man. His chapter "Death, or Life Eternal?" argued for Christian immortality and quoted verses from the Bible.[49][50] From 1948 to 1962, Compton was an elder of theSecond Presbyterian Church in St. Louis.[49] In his later years, he co-authored the bookMan's Destiny in Eternity. Compton setJesus as the center of his faith in God's eternal plan.[49] He once commented that he could see Jesus' spirit at work in the world as an aspect of God alive in men and women.[49]
^Pfeiffenberger, Amy M. (Winter 1989). "Democracy at Home: The Struggle to Desegregate Washington University in the Postwar Era".Gateway-Heritage.10 (3). Missouri Historical Society:17–24.
^Eikner, Allen V. (1980).Religious Perspectives and Problems An Introduction to the Philosophy of Religion. University Press of America. pp. 194–203.ISBN978-0-8191-1215-6
^"Compton, Arthur H., House".National Historic Landmark summary listing. National Park Service. Archived fromthe original on February 12, 2012. RetrievedJuly 27, 2013.
Bernstein, Barton J. (1988). "Four Physicists and the Bomb: The Early Years, 1945–1950".Historical Studies in the Physical and Biological Sciences.18 (2):231–263.doi:10.2307/27757603.JSTOR27757603.; covers Oppenheimer, Fermi, Lawrence and Compton.
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