Thermodynamics the work of French physicist Nicolas Léonard Sadi Carnot (1824) who believed that engine efficiency was the key that could help France win the Napoleonic Wars. Scots-Irish physicist Lord Kelvin was the first to formulate a concise definition of thermodynamics in 1854 which stated, "Thermo-dynamics is the subject of the relation of heat to forces acting between contiguous parts of bodies, and the relation of heat to electrical agency." The initial application of thermodynamics to mechanical heat engines was extended early on to the study of chemical compounds and chemical reactions. Chemical thermodynamics studies the nature of the role of
Black hole thermodynamics then they have zero temperature and, by the no-hair theorem, zero entropy, and the laws of black-hole mechanics remain an analogy. However, when quantum-mechanical effects are taken into account, one finds that black holes emit thermal radiation (Hawking radiation) at a temperature From the first law of black-hole mechanics, this determines the multiplicative constant of the Bekenstein–Hawking entropy, which is Gary Gibbons and Hawking have shown that black-hole thermodynamics is more general than black holes—that cosmological event horizons also have an entropy and temperature. More fundamentally, 't Hooft and Susskind used the laws of black-hole thermodynamics to argue for a