Richard Threlkeld Cox (August 5, 1898 – May 2, 1991) was a professor of

physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

Johns Hopkins University The Johns Hopkins University (often abbreviated as Johns Hopkins, Hopkins, or JHU) is a private university, private research university in Baltimore, Maryland, United States. Founded in 1876 based on the European research institution model, J ...

, known for

Cox's theorem Cox's theorem, named after the physicist Richard Threlkeld Cox, is a derivation of the laws of probability theory from a certain set of postulates. This derivation justifies the so-called "logical" interpretation of probability, as the laws of pr ...

relating to the foundations of

probability Probability is a branch of mathematics and statistics concerning events and numerical descriptions of how likely they are to occur. The probability of an event is a number between 0 and 1; the larger the probability, the more likely an e ...

Biography

He was born in

Portland, Oregon Portland ( ) is the List of cities in Oregon, most populous city in the U.S. state of Oregon, located in the Pacific Northwest region. Situated close to northwest Oregon at the confluence of the Willamette River, Willamette and Columbia River, ...

, the son of attorney Lewis Cox and Elinor Cox. After Lewis Cox died, Elinor Cox married John Latané, who became a professor at Johns Hopkins University in 1913. In 1915 Richard enrolled at Johns Hopkins University to study physics, but his studies were cut short when he was drafted for

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

. He stayed in the US after being drafted and returned to Johns Hopkins University after the war, completing his BA in 1920. He earned his PhD in 1924; his dissertation was ''A Study of Pfund's Pressure Gauge''. He taught at

New York University New York University (NYU) is a private university, private research university in New York City, New York, United States. Chartered in 1831 by the New York State Legislature, NYU was founded in 1832 by Albert Gallatin as a Nondenominational ...

(NYU) from 1924 to 1943, before returning to Johns Hopkins to teach. He studied probability theory, the scattering of electrons, and the discharges of

electric eel The electric eels are a genus, ''Electrophorus'', of neotropical freshwater fish from South America in the family Gymnotidae, of which they are the only members of the subfamily Electrophorinae. They are known for their electric fish, ability ...

s. Richard Cox's most important work was

. His wife, Shelby Shackleford (1899

Halifax, Virginia Halifax is a town in Halifax County, Virginia, United States, along the Banister River. The population was 1,309 at the 2010 census. It is the county seat of Halifax County. History Halifax County Courthouse, Mountain Road Historic District, ...

– 1987), whom he married in 1926, was an accomplished artist and illustrated ''Electric Eel Calling'', a book on electric eels. He died on May 2, 1991. His doctoral students include Carl T. Chase and Clifford Shull.

Cox and parity violation

According to T. D. Lee and C. N. Yang,

parity violation In physics, a parity transformation (also called parity inversion) is the flip in the sign of ''one'' spatial coordinate. In three dimensions, it can also refer to the simultaneous flip in the sign of all three spatial coordinates (a point ref ...

implies that electrons produced by β decay should be longitudinally polarized. In 1959,

Lee Grodzins Lee Grodzins (July 10, 1926 – March 6, 2025) was an American physicist and inventor who was a longtime professor of physics at the Massachusetts Institute of Technology (MIT). The family settled in Manchester, New Hampshire, where his father ra ...

indicated how a 1928 experiment by R. T. Cox, C. G. McIlwraith, and B. Kurrelmeyer on double scattering of β rays from radium confirms the polarization effect predicted by Lee and Yang. Carl T. Chase in 1929 and 1930 performed experiments confirming the 1928 experiment by Cox, McIlwraith, and Kurrelmeyer.

Louis Witten interview

Witten: ... I wanted to tell you something about Richard Cox. You mentioned Richard Cox. He did a lot of things, but he also did some experiments in

condensed matter physics Condensed matter physics is the field of physics that deals with the macroscopic and microscopic physical properties of matter, especially the solid and liquid State of matter, phases, that arise from electromagnetic forces between atoms and elec ...

. He discovered an anomaly which wasn't consistent with physics. It couldn't be explained. It wasn't at all consistent, and he was told his experiment was wrong, and he knew that his experiment was right. So he published it, and it was an anomaly in the literature. Some years later, it was discovered that parity wasn't conserved, and his anomaly was non-parity. It's well known now by many people that his experiment was the first experiment that would have shown parity wasn't conserved if they had interpreted it correctly.
Rickles: But he didn't give that interpretation; he just thought there was something strange.
Witten: That's right. But he knew that his experiment was right and that people were trying to tell him that his experiment was wrong.

Selected works

* Cox, R. T., "Of Inference and Inquiry - An Essay in Inductive Logic", In The Maximum Entropy Formalism, Ed. Levine and Tribus, M.I.T. Press, 1979. * * ''The Algebra of Probable Inference'', Johns Hopkins University Press, Baltimore, MD, (1961).

References

External links

* {{DEFAULTSORT:Cox, Richard Threlkeld 1898 births 1991 deaths 20th-century American physicists American statisticians Johns Hopkins University faculty Scientists from Portland, Oregon Johns Hopkins University alumni New York University faculty American military personnel of World War I