In this study, the irreversible thermodynamics of the universe in the framework of f(R) gravity has been studied following standard Eckart theory of non-equilibrium thermodynamics. For a spatially flat universe, validity of GSLT and thermodynamic equilibrium have been examined both for apparent and event horizon as bounding horizons.The general result has been verified for exponential models of f(R) gravity and it is shown that GSLT holds on both apparent and event horizon, but thermodynamic equilibrium does not hold on event horizon.

中文翻译：

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$$\varvec{f}(R)$$ f ( R ) 引力下的宇宙不可逆热力学

在这项研究中，根据非平衡热力学的标准埃卡特理论，研究了 f(R) 引力框架下宇宙的不可逆热力学。对于一个空间平坦的宇宙，GSLT 和热力学平衡的有效性已经在视视界和事件视界作为边界视界进行了检验。 一般结果已经在 f(R) 引力的指数模型中得到验证，并且表明 GSLT 对视视界和事件视界都成立。和事件视界，但热力学平衡并不适用于事件视界。