J. G. Fox
John G. Fox | |
---|---|
Born | March 5, 1916 |
Died | July 24, 1980 | (aged 64)
Nationality | U.S. |
Alma mater | Princeton University |
Scientific career | |
Fields | Nuclear physics |
Institutions | Carnegie Mellon University |
John Gaston Fox (March 5, 1916 – July 24, 1980) was an American nuclear physicist. He earned his PhD from Princeton in 1941 and was soon recruited to work on the
Brief biography
Jack Fox, as he was always known, was born in Biggar, Saskatchewan.
Special relativity and the extinction theorem
The second postulate of Einstein's theory of special relativity states that the speed of light is invariant, regardless of the velocity of the source from which the light emanates. The extinction theorem (essentially) states that light passing through a transparent medium is simultaneously extinguished and re-emitted by the medium itself.[2] This implies that information about the velocity of light from a moving source might be lost if the light passes through enough intervening transparent material before being measured. All measurements previous to the 1960s intending to verify the constancy of the speed of light from moving sources (primarily using moving mirrors, or extraterrestrial sources) were made only after the light had passed through such stationary material — that material being that of a glass lens, the terrestrial atmosphere, or even the incomplete vacuum of deep space. In 1961, Fox decided that there might not yet be any conclusive evidence for the second postulate: "This is a surprising situation in which to find ourselves half a century after the inception of special relativity."[3] Regardless, he remained fully confident in special relativity, noting that this created only a "small gap" in the experimental record.[3]
Fox suggested that better experiments were possible, in order to close that "small gap". Since photons with higher energies will, on average, travel much farther in any material before being extinguished and re-emitted, experiments using gamma rays instead of lower-energy visible light or x-rays would be dramatically less sensitive to the extinction problem. In 1963, along with T. A. Filippas (also of Carnegie Tech), Fox examined 68 MeV gamma rays emitted in the forward and backward directions by
Reexamination of Ritz's emission theory
The
Other professional activities
In the late 1940s and 1950s, Fox was part of the
Further reading
In 2004, Alberto Martínez examined the rejection of Ritz's emission theory in favor of special relativity from a historical perspective.[8] That work discusses Fox's findings at some length.
References
- ^ His birthname was James Gaston Fox, James being the English form of "Jacques", the name of his Swiss-born jeweller father. His parents called him Jacques, his friends called him Jack, and as a young man, Jack legally changed his name from James Gaston to John Gaston, to avoid inevitably being called "Jim".
- ^ M. Born and E.Wolf. Principles of Optics (6th ed.). Pergamon Press., 1986, p.101
- ^ .
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- ^ "[History of the] Kanpur Indo-American Programme (KIAP)". Archived from the original on October 28, 2013. Retrieved August 6, 2014.
- S2CID 123043585