Howard P. Robertson | |
|---|---|
| Born | (1903-01-27)January 27, 1903 Hoquiam, Washington, U.S. |
| Died | August 26, 1961(1961-08-26) (aged 58) Pasadena, California, U.S. |
| Alma mater | University of Washington California Institute of Technology |
| Known for | Friedmann–Lemaître–Robertson–Walker metric Poynting–Robertson effect Robertson–Schrödinger relation |
| Awards | Medal for Merit (1946) |
| Scientific career | |
| Fields | Physicist |
| Institutions | California Institute of Technology Princeton University |
| Thesis | On Dynamical Space-Times Which Contain a Conformal Euclidean 3-Space (1925) |
| Doctoral advisor | Harry Bateman |
| Doctoral students | Banesh Hoffmann Eugene Parker Ralph J. Slutz Abraham H. Taub |
Howard Percy "Bob" Robertson (January 27, 1903 – August 26, 1961) was an Americanmathematician andphysicist known for contributions related tophysical cosmology and theuncertainty principle. He was Professor of Mathematical Physics at theCalifornia Institute of Technology andPrinceton University.
Robertson made important contributions to the mathematics ofquantum mechanics,general relativity anddifferential geometry. Applying relativity tocosmology, he independently developed the concept of anexpanding universe. His name is most often associated with thePoynting–Robertson effect, the process by whichsolar radiation causes a dust mote orbiting a star to loseangular momentum, which he also described in terms of general relativity.
DuringWorld War II, Robertson served with theNational Defense Research Committee (NDRC) and theOffice of Scientific Research and Development (OSRD). He served as technical consultant to theSecretary of War, the OSRD Liaison Officer in London, and the Chief of the Scientific Intelligence Advisory Section atSupreme Headquarters Allied Expeditionary Force.
After the war Robertson was director of theWeapons Systems Evaluation Group in theOffice of the Secretary of Defense from 1950 to 1952, chairman of theRobertson Panel onUFOs in 1953 and scientific advisor to theNATOSupreme Allied Commander Europe (SACEUR) in 1954 and 1955. He was chairman of the Defense Science Board from 1956 to 1961, and a member of thePresident's Science Advisory Committee (PSAC) from 1957 to 1961.
TheRobertson crater on the far side of the Moon is named in his honor.
Howard Percy Robertson, was born inHoquiam, Washington, on January 27, 1903, the oldest of five children of George Duncan Robertson, an engineer who built bridges in Washington state, and Anna McLeod, a nurse. His father died when he was 15 years old, but although money was short, all five siblings attended university. He entered theUniversity of Washington inSeattle in 1918, initially with the intention of studying engineering, but he later switched to mathematics.[1] He earned aBachelor of Science degree in mathematics in 1922 and aMaster of Science in mathematics and physics in 1923.[2]
In 1923 Robertson married Angela Turinsky, a philosophy and psychology student at the University of Washington.[2] They had two children: George Duncan, who became a surgeon, and Marietta, who later marriedCalifornia Institute of Technology (Caltech) historianPeter W. Fay. At the University of Washington he also metEric Temple Bell, who encouraged him to pursue mathematics at Caltech.[2] Robertson completed hisPhD dissertation in mathematics and physics there in 1925 under the supervision ofHarry Bateman, writing "On Dynamical Space-Times Which Contain a Conformal Euclidean 3-Space".[3][4]
Upon receipt of his doctorate, Robertson received aNational Research Council Fellowship to study at theUniversity of Göttingen in Germany, where he metDavid Hilbert,Richard Courant,Albert Einstein,Werner Heisenberg,Erwin Schrödinger,Karl Schwarzschild,John von Neumann andEugene Wigner.[5] He foundMax Born unsympathetic to his concept of anexpanding universe, which Born considered "rubbish".[6] He also spent six months atLudwig Maximilian University of Munich, where he was a post-doctoral student ofArnold Sommerfeld.[7]
Robertson returned to the United States in 1927, and became anassistant professor of mathematics at Caltech. In 1928,[8] he accepted a position as an assistant professor of mathematical physics atPrinceton University, where he became anassociate professor in 1931, and a professor in 1938.[9] He spent 1936 on sabbatical at Caltech.[10] His interest ingeneral relativity anddifferential geometry led to a series of papers in the 1920s that developed the subject.[11][12][13]
Robertson wrote three important papers on the mathematics ofquantum mechanics.[11] In the first, written in German, he looked at the coordinate system required for theSchrödinger equation to be solvable.[14] The second examined the relationship between thecommutative property and Heisenberg'suncertainty principle,[15] generalizing the latter for any twoHermitian operators.[16] The third extended the second to the case of observables.[17] In 1931 he published a translation of Weyl'sThe Theory of Groups and Quantum Mechanics.[11]
It was Robertson's anonymous 1936 critical peer review of a paper submitted by Albert Einstein toPhysical Review which caused Einstein to withdraw the paper from consideration.[18][19]
Yet perhaps Robertson's most notable achievements were in applying relativity tocosmology.[20] He independently developed the concept of an expanding universe,[21] which would imply distant galaxies as seen from Earth would beredshifted—a phenomenon previously confirmed byVesto Slipher[22][23]. Robertson went on to apply the theory of continuous groups inRiemann spaces to find all the solutions that describe the cosmological spaces.[24] This was extended byArthur Geoffrey Walker in 1936, and is today widely known in theUnited States as theRobertson–Walker metric.[20]
One of Robertson's landmark papers, a brief note inThe Annals of Mathematics, entitled a "Note on the preceding paper: The two body problem in general relativity", solved that problem within a degree of approximation not improved on for several decades. Earlier work, such as theSchwarzschild metric, were for a central body that did not move, while Robertson's solution considered two bodies orbiting each other. Nevertheless, his solution failed to includegravitational radiation, so the bodies orbit forever, rather than approaching each other.[25]
Yet Robertson's name is most often associated with thePoynting–Robertson effect,[20] the process by whichsolar radiation causes a dust mote orbiting a star to loseangular momentum. This is related toradiation pressure tangential to the grain's motion.John Henry Poynting described it in 1903 based on the "luminiferous aether" theory, which was superseded by Einstein's theories of relativity. In 1937, Robertson described the effect in terms of general relativity.[26]
Robertson developed the theory ofinvariants of tensors to derive theKármán–Howarth equation in 1940, which was later used byGeorge Batchelor andSubrahmanyan Chandrasekhar in the theory of axisymmetric turbulence to deriveBatchelor–Chandrasekhar equation.[27]
Aside from his work in physics, Robertson played a central role in American scientific intelligence during and after World War II. He was approached byRichard Tolman shortly afterWorld War II began in 1939, and began working for the Committee for Passive Protection Against Bombing. This was absorbed with other groups into Division 2 of theNational Defense Research Committee (NDRC), with Robertson engaged in the study ofterminal ballistics.[28]
In 1943, Robertson became theOffice of Scientific Research and Development (OSRD) chief scientific liaison officer in London.[28] He became close friends withReginald Victor Jones,[29] andSolly Zuckerman praised the work Robertson and Jones did on scrambling radar beams and beacons.[30] In 1944 Robertson also became a technical consultant to theSecretary of War, and the chief of the Scientific Intelligence Advisory Section atSupreme Headquarters Allied Expeditionary Force.[28] His fluency in German helped him to interrogate German scientists, including rocket scientists involved in theV-2 rocket program.[31] He was awarded theMedal for Merit for his contributions to the war effort.[10]
After the war, Robertson accepted a professorship at Caltech in 1947. He would remain there for the rest of his career, except for long periods of government service.[32][28] He was aCentral Intelligence Agency classified employee and director of the Weapons System Evaluation Group in theOffice of the Secretary of Defense[33] from 1950 to 1952, and scientific advisor in 1954 and 1955 to theNATOSupreme Allied Commander Europe (SACEUR),GeneralAlfred M. Gruenther. In 1953 he chaired theRobertson Panel, which investigated a wave ofUFO reports in 1952. He was chairman of the Defense Science Board from 1956 to 1961, and a member of thePresident's Science Advisory Committee (PSAC) from 1957 to 1961.[28]
He was a member of theNational Academy of Sciences, serving as its foreign secretary from 1958 until his death in 1961, theAmerican Academy of Arts and Sciences, theAmerican Mathematical Society, theAmerican Physical Society, theAmerican Astronomical Society, theAmerican Philosophical Society, theOperational Research Society, and theSociety for Industrial and Applied Mathematics.[34]
In August 1961, Robertson was hospitalized after being injured in a car accident. He suffered apulmonary embolism and died on August 26, 1961.[9] He was survived by his wife and children.[2] His papers were donated to the Caltech Archives by his daughter and son-in-law in 1971.[35]
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