7th ESHS Conference Prague 2016

7th International Conference of the European Society for the History of Science
d) Thus while the interplay is unavoidable in historical, foundational and educational approaches, it will
be shown that through an analysis of the classics some relevant issues acquire a clearer perspective.
Keywords: energy conservation, Feynman, Mayer, Joule, Helmholtz, Weber, Clausius, Planck, Haas,
Kuhn
References:
Planck, Max. Das Princip Der Erhaltung Der Energie, Leipzig, B.G. Teubner, 1887.
Energy: conservation versus equivalence (ID 184)
Ricardo Lopes Coelho (Faculdade de Ciências da Universidade de Lisboa, Lisbon, Portugal)
Energy has been thought of as a substance (Lancor 2014). Mayer, Joule (Coelho 2014) and Helmholtz
(Bevilacqua 1993) did not discovery any substance. This raises the question of what energy is (Bächtold
and Guedj 2014).
In the first half of the 19th century, people thought that the quantity of heat was constant. Due to
this, they understood heat as a substance. In the 1840s, Mayer and Joule showed that the quantity of
heat changes. This finding, which was experimentally supported, was expressed by the mechanical
equivalent of heat. To negate that idea of heat as a substance, they claimed that heat is a force, which
can be transformed (Mayer 1842, 1845), or heat is motion (Joule 1843, 1850).
This period is crucial for understanding the concept of energy for the following reasons. The history of
the energy conservation principle includes three lines of development: one is related with Mayer; another
with Joule; and a 3rd one with equivalence. According to this last one, the principle of the energy
conservation is a principle of equivalence. This concept appeared in the 1860s and was maintained for
about 5 decades. The other two concepts have been more successful. We still say that energy cannot
be created or destroyed but only transformed, which represents that which Mayer said about force.
Force was a result of an interpretation. Therefore, the concept of energy presented in many textbooks
is of the same type.
Keywords: conservation of energy, equivalence, Mayer, Joule
References:
Bächtold, M. & Guedj, M. (2014) Teaching Energy Informed by the History and Epistemology of the
Concept with Implications for Teacher Education. In M R Matthews (ed.) International Handbook of
Research in History, Philosophy and Science Teaching. Dordrecht: Springer, pp 211–243
Bevilacqua, F. (1993). Helmholtz’ Ueber die Erhaltung der Kraft. In D. Cahan (Ed.), Hermann von
Helmholtz and the foundations of the nineteenth-century science. Berkeley, Los Angeles: University of
California Press, pp 291–333
Coelho, R. L. (2014) On the Concept of Energy: Eclecticism and Rationality. Science & Education 23,
1361–1380
Lancor, R. (2014). Using metaphor theory to examine conceptions of energy in biology, chemistry, and
physics. Science & Education, 23, 1245–1267
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