标题： 对于一个平坦的宇宙，$C_P/C_V=-q$：宇宙学中的另一个巧合？ 显示英文标题

标题： For a flat Universe, $C_P/C_V=-q$ : another coincidence in Cosmology?

摘要： 本文研究了具有耗散的FLRW宇宙动力学视界上的引力热力学。假设耗散是由绝热引力粒子产生引起的。为了进行热力学研究，我们考虑了贝肯斯坦-霍金公式，并且还假设了一般研究中的非零曲率$\kappa$。特别是，我们研究了模型中的统一第一定律、广义第二定律和热力学稳定性。具体热容量被用于热力学稳定性的研究。我们的研究表明了一个很好的结果！在具有耗散的平坦FLRW宇宙中，恒压和恒容下的比热容之比正是减速参数的负值。在经典热力学中，这个比值被称为等熵膨胀因子（对于理想气体则是绝热指数）。一个更有趣的事实是，这种关系与所使用的宇宙学模型无关。因此，这实际上是大爆炸宇宙学中的一个普遍结果。我们讨论了这一结果对宇宙演化的影响。最后，我们确定了保证模型中热力学稳定的有效状态方程和粒子产生率的约束条件。 显示英文摘要

摘要： This paper deals with gravitational thermodynamics on the dynamical apparent horizon of an FLRW universe with dissipation. The dissipation is assumed to arise due to adiabatic gravitational particle creation. For the thermodynamic study, we consider the Bekenstein-Hawking formalism and also assume a nonzero curvature $\kappa$ for a general study. In particular, we study the unified first law, the generalized second law, and thermodynamic stability in our model. The specific heat capacities are taken into account for the study of thermodynamic stability. Our study reveals a nice result! The ratio of the specific heat capacity at constant pressure and that at constant volume in a flat FLRW universe with dissipation is nothing but the negative of the deceleration parameter. In classical thermodynamics, this ratio is known as the isentropic expansion factor or (for ideal gases) the adiabatic index. A more interesting fact that has come to light is that this relation is independent of the cosmological model used. So, this is actually a generic result in Big Bang Cosmology. We discuss the implications of this result on the evolution of the Universe. Finally, we determine the constraints on the effective equation of state and the particle creation rate which guarantees thermodynamic stability in our model.