In thermodynamics, cosmological thermodynamics or "astrothermodynamics" is the study of the relation between the laws of thermodynamics and the functioning, dynamics, and evolution of the universe, from the sub-atomic to super-galactic range. Topics in this field is black hole thermodynamics, black hole entropy, and the Boltzmann brain problem.

In 1970, Stephen Hawking introduced the model of black hole entropy, and hence black hole thermodynamics.

In 1939, Subrahmanyan Chandrasekhar, in his book An Introduction to the Study of Stellar Structure, devoted his the first chapter, on astrophysical thermodynamics, to laying out a thermodynamic foundation for the study of stellar structure using the thermodynamics of Greek mathematician Constantin Caratheodory (1908), in particular the so-called Caratheodory theorem.

In 2001, Eric Chaisson, his Cosmic Evolution: the Rise of Complexity in Nature, outlined a “lightly quantitative, thermodynamics-oriented treatment” of radiation, matter, and ‘life’ (powered CHNOPS+ things), using what he calls “energy flow-rate density” (ΡΊ), in units of ergs per second per gram, as a complexity measure for phenomena of all kinds and scales. [2]
The general nature of the thermodynamic operation of the universe, however, is relatively unknown, depending on phenomenon such as dark energy, boson-fermion relationships, the open or closed thermodynamic system possibilities of the universe, the puzzling rate of expansion of the universe, a lack of a unified theory of the fundamental forces or interactions, e.g. electromagnetic vs. gravity, the nature of black holes and entropy, etc. The central question in human thermodynamics is how does the thermodynamic operation of the universe relate, interact, or connect to the thermodynamic operation of human life, if at all?

1. (a) Chandrasekhar, Subrahmanyan. (1939). An Introduction to the Study of Stellar Structure (ch. 1: Laws of Thermodynamics, pg. 11-). University of Chicago Press.
(b) Kirkwood, John G. and Oppenheim, Irwin. (1961). Chemical Thermodynamics (pg. 36). McGraw-Hill.
2. Chaisson, Eric J. (2001). Cosmic Evolution - the Rise of Complexity in Nature. Cambridge, Massachusetts: Harvard University Press.

Further reading
● Akbar, M. (2008). “Viscous Cosmology and Thermodynamics of Apparent Horizon” (abs), Chinese Phys. Lett. 25: 4199-4202.
● Lavenda, Bernard H. (1995). Thermodynamics of Extremes (backcover). Horwood Publishing.

External links
● Thermodynamics of the universe - Wikipedia.
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