|A depiction of the rise and fall of the Roman empire (375BC-544AD), the color red depicting the changes in the territory (volume) of a system of about 45-million people (human molecules) of the Roman empire as it expands, doing thermodynamic pressure volume work, against its surroundings (neighboring countries), and then contracts, during its fall, after Romulus is disposed, over the course of about 1,400-years.|
In 1776, Edward Gibbon published volume one of his The History of the Decline and Fall of the Roman Empire, wherein he “blamed the otherworldly preoccupations of Christianity for the decline of the Roman empire”. (Ѻ)
See main: History thermodynamicsIn 1910, American historian Henry Adams, in his A Letter to the American Teachers of History, seems to argue that the rise and fall aspects of civilization throughout history can be explained on a mixture of the nebular hypothesis applied to contractions and expansions of systems or societies of human molecules over time leading to ultimate equilibrium as determined by the second law of thermodynamics and Gibbs phase rule: 
“The physicist-historian may begin with his favorite figure of gaseous nebula, and may offer to treat primitive humanity as a volume of human molecules of unequal intensities, tending to dissipate energy, and to correct the loss by concentrating mankind into a single, dense mass like the sun. History would then become a record of successive phases of contraction divided by periods of explosion, tending always towards an ultimate equilibrium in the form of a volume of human molecules of equal intensity, without coordination.”
In 1985, writer Olga Cooke noted that, in literature, it has been viewed that the laws of thermodynamics were seen to control the rise and fall of civilizations. 
In a 1997 article, American literary theorist Bruce Clarke discusses energy and thermodynamics in terms of the rise and fall of a mysterious civilization. 
In 2003, American economist Jeremy Rifkin wrote a chapter section on “The Thermodynamics of Rome”, in which he attempts to explain the role of energy in the rise and fall of civilizations in the context of thermodynamics. 
In 2009, American physical chemist Thomas Wallace attempted to explain the cyclical rise and fall of civilizations using the chemical thermodynamic model of the “useful life” of the chemical reaction aspects of a car battery, as mandated by the second law. 
The diagram show (above) illustrates the changes in the territory (volume) of a system of about 45-million people (human molecules) of the Roman empire as it expands, doing thermodynamic pressure volume work, against its surroundings (neighboring countries), and then contracts (during its fall), over the course of about 1,400-years.  In modeling the Roman empire as a thermodynamics system, on the model of the working body of the steam engine, the rise and fall can be considered as a thermodynamics 'transformation', occurring over a span of about 1,400-years. To give an idea of 'human pressure' (a elusive concept), which in the Daniel Bernoulli perspective is defined as the average impact of the particles of a system, in this case Roman citizens (human molecules), on the surface or boundary of their containing vessel (in this case national borders), one can use the census population changes per century as a gauge of population density and hence collision frequency in the sense that as nation well-being increases so to does the rate of reproduction, whereby the increase in products (babies) of the reaction, require more volumetric space, which instills a need in the system to expand, loosely speaking.
The population of the world at 1 AD has been considered to be between 200 and 300 million people. In that same period, the population of the early empire under Augustus (27 BC – 14 AD) has been placed at about 45 million.  Using 300 million as the world benchmark, the population of the Empire under Augustus would've made up about 15% of the world's population. In this case, in order for the Roman system to expand outward to its eventual largest volume (116 AD), the pressure in the Roman system would have been greater than that of the territory of the neighboring surrounding world.
1. Wallace, Thomas P. (2009). Wealth, Energy, and Human Values: the Dynamics of Decaying Civilizations from Ancient Greece to America (pg.xv). AuthorHouse.
2. Adams, Henry. (1910). A Letter to American Teachers of History. Washington.
3. Rifkin, Jeremy. (2003). Hydrogen Economy: the Creation of the Worldwide Energy Web and the Redistribution of Power on Earth (Thermodynamics of Rome, pgs. 57-63). Penguin Group.
4. Cooke, Olga M. (1985). “Bely’s Moscow Novels and Zamyatin’s Robert Mayer: A Literary Response to Thermodynamics”, Slavonic & East European Review (SEER), Vol. 63, April.
5. Clarke, Bruce. (1997). “A Scientific Romance: Thermodynamics and the Fourth Dimension in Charles Howard’s Hinton’s ‘The Persian King’.” Essay, Supplement to Science, Technology, & the Arts: Weber Studies: an Interdisciplinary Humanities Journal, Vol. 14, No. 1, Winter. altx.com.
6. Haywood, John. (2001). Atlas of World History (pgs. 2.01-2.05). Barnes & Noble Books.
7. Roman empire population – UNRV.com.
● White, Leslie. (1959). The Evolution of Culture: the Development of Civilization to the Fall of Rome (ch. 2: Energy and Tools: Wilhelm Ostwald, Lotka, Negative entropy, pgs. 33-49). McGraw-Hill.
● Brander, Bruce. (1998). Staring into Chaos: Explorations in the Decline of Western Civilization (sections: A Scientific Law of History: Henry Adams, pgs. 41-42; The Law of Civilization and Decay: Brooks Adams, pgs. 43-45; Pitirim Sorokin, pgs. 235-67; entropy, pg. 258; thermodynamics, pg. 45). Spence Publishing Co.
● Porreca, David. (2012). “On the Thermodynamics of Civilizations: Rise and Falls of Empires” (V), Waterloo, ArtsFacuty, May 22.