br While the two previous examples are familiar to all
While the two previous examples are familiar to all physicists they are perhaps too broad and not mathematical enough to be really convincing. Taken from particle physics, the next examples show that analogies were of great help even mathematically for they helped to build an appropriate theoretical framework.
In the 1960s, in an attempt to describe strongly interacting particles, physicists created what is now called quantum chromodynamics (QCD) and for that purpose they used quantum electrodynamics (QED) as a blue print. QED was much simpler than QCD because it ABT-263 (Navitoclax) considered particles which have only electromagnetic interactions.
The next example is similar in the sense that it was also an extension of electromagnetism. In the 1970s and 1980s so-called Yang–Mills gauge theories took model on gauge invariance in electromagnetism in which it is recognized that there is a degree of arbitrariness in the definition of the scalar and vector potentials. Although this idea was introduced in the 1950s (see ) such gauge theories became commonly used in particle physics only a few decades later.
The role of analogy in the history of physics was studied and emphasized by the French physicist Pierre Duhem as attested by the following excerpt (, p. 140). ‘‘The history of physics shows that the search of analogies between different categories of phenomena may have been the most productive of approaches tried by theoretical physics’’.
It should not come as a surprise, therefore, that when they turn to the fields of biology and medicine, physicists adopt a comparative perspective with the purpose of finding parallels and common rules for apparently unrelated phenomena.
It is hoped that the macro-biological perspective that we develop in the present paper may prove of value in complement to the highly detailed descriptions permitted by the techniques of molecular biology and genetic sequencing.
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 Bureau of the Census: Mortality Statistics (various years until 1936) Washington, Government Printing Office. In 1937 the name of this periodical
was changed into: Vital Statistics of the United States, Part I as indicated in the following reference.
 Bureau of the Census: Vital Statistics of the United States (various years starting in 1937) Part 1: Natality and mortality data for the United States tabulated by place of occurrence with supplemental tables for Hawaii, Puerto Rico, and the Virgin Islands. Washington, Government Printing Office. The volumes of both the Mortality Statistics and Vital Statistics are available online. As of 2017 the relevant address was: https://www.cdc.gov/nchs/products/vsus.htm#1950.  M. van der Walt, J. Lancaster, K. Shean, Tuberculosis case fatality and other causes of death among multidrug-resistant tuberculosis patients in a high HIV prevalence setting, 2000-2008, South Africa, PLoS One 11 (3) (2016).
 B.M. Roehner, Patterns of Speculation. A Study in Observational Econophysics, Cambridge University Press, Cambridge (UK), 2002.
 G. Canetti, Le bacille de Koch dans la lésion tuberculeuse du poumon. Flammarion, Paris, 1946, Translated into English under the title: The tubercle bacillus in the pulmonary lesion of man, Histobacteriology and Its Bearing on the Therary of Pulmonary Tuberculosis, Springer, New York, 1955.
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