Dear Colleagues,

Cosmology is experiencing its golden era, when more and more data, released by current and future missions, is providing a way to test cosmological models with a high precision. As pointed by the observations from the last decade, the current expansion of the universe is being accelerated, due to the presence of an unknown fluid, which behaves effectively as a perfect fluid with negative pressure and which has been called dark energy. Such a fluid raises fundamental thermodynamical issues that are unknown or at least not yet well understood. Dark energy entropy, its specific heat or how (non)-adiabatic perturbations may be affected by each dark energy model are topics to be considered in this Special Issue. Additionally, possible interactions among dark energy and dark matter may affect the thermodynamics of both unknown components. Moreover, the thermodynamics of the early universe, particularly along and at the end of the inflationary period, have been deeply studied and required special analyses, which can contribute to a better understanding of the universe evolution.

On the other hand, since the establishment of the fundamental connection between gravitation and standard thermodynamic systems following Hawking’s temperature and Bekenstein’s area law, the study of black hole thermodynamics has become one of the most promising scenarios to test our comprehension of gravitational interaction in combination with quantum effects. The consideration of modified theories of gravity offer new scenarios regarding, among many others, the definition of black hole entropy, the validity of the second law, the existence of different kinds of phase transitions, the description of the last stages of black hole evaporation, or the resolution of the information loss problem.

This Special Issue is devoted to discuss the latest achievements on the understanding of the thermodynamics of gravitational physics and cosmology, and particularly on those theories beyond General Relativity. We expect that this Special Issue can account for new physics regarding properties of dark energy and its alternatives, as well as new insights on the thermodynamical properties of gravitational systems such as black holes or wormholes.

Dr. Diego Sáez-Chillón Gómez
Dr. Diego Rubiera-Garcia
Guest Editors

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• Quantum aspects of black holes: thermodynamics, evaporation, phase transitions
• Black hole entropy
• Modified theories of gravity
• Cosmology
• Dark energy
• Inflation