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Which Physical Quantity Deserves the Name “Quantity of Heat”?

Herrmann, Friedrich ORCID iD icon 1; Pohlig, Michael 1
1 Karlsruher Institut für Technologie (KIT)


“What is heat?” was the title of a 1954 article by Freeman J. Dyson, published in Scientific American. Apparently, it was appropriate to ask this question at that time. The answer is given in the very first sentence of the article: heat is disordered energy. We will ask the same question again, but with a different expectation for its answer. Let us imagine that all the thermodynamic knowledge is already available: both the theory of phenomenological thermodynamics and that of statistical thermodynamics, including quantum statistics, but that the term “heat” has not yet been attributed to any of the variables of the theory. With the question “What is heat?” we now mean: which of the physical quantities deserves this name? There are several candidates: the quantities Q, H, Etherm and S. We can then formulate a desideratum, or a profile: What properties should such a measure of the quantity or amount of heat ideally have? Then, we evaluate all the candidates for their suitability. It turns out that the winner is the quantity S, which we know by the name of entropy. In the second part of the paper, we examine why entropy has not succeeded in establishing itself as a measure for the amount of heat, and we show that there is a real chance today to make up for what was missed.

Verlagsausgabe §
DOI: 10.5445/IR/1000137472
Veröffentlicht am 01.10.2021
DOI: 10.3390/e23081078
Zitationen: 8
Web of Science
Zitationen: 7
Zitationen: 8
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Theoretische Festkörperphysik (TFP)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2021
Sprache Englisch
Identifikator ISSN: 1099-4300
KITopen-ID: 1000137472
Erschienen in Entropy
Verlag MDPI
Band 23
Heft 8
Seiten Art.-Nr.: 1078
Bemerkung zur Veröffentlichung Gefördert durch den KIT-Publikationsfonds
Vorab online veröffentlicht am 19.09.2021
Schlagwörter heat; balance equation for heat; entropy as heat; enthalpy; thermal energy; caloric
Nachgewiesen in Web of Science
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