标题： 相变与熵驱动宇宙中的热力学稳定性 显示英文标题

标题： Phase Transition and Thermodynamic Stability in an Entropy-driven Universe

摘要： 受重力数学可从最大熵的统计要求中再现这一概念的启发，我们研究了在爱因斯坦-希尔伯特作用量中引入熵源项的后果。 对于由这种熵源驱动并被随时间演变的视界包围的空间均匀宇宙系统，我们提出了热力学第二定律的一个修改版本。 找到了一个控制内部熵分布的显式微分方程。 通过内部熵的海森矩阵分析，我们检查了{\Lambda }冷暗物质宇宙学、统一的宇宙膨胀和无奇点的反弹宇宙中的热力学稳定性。 我们从恒定体积下比热的发散中找到了这些演化过程中二阶相变的数学条件。 该条件纯粹是运动学的，并且是二次性质的，将减速度参数和急动参数联系起来，在参数空间上勾勒出一条有趣的曲线。 该条件即使没有熵源项也有效，可能是任何相变的一般特性。 显示英文摘要

摘要： Motivated by the notion that the mathematics of gravity can be reproduced from a statistical requirement of maximal entropy, we study the consequence of introducing an entropic source term in the Einstein-Hilbert action. For a spatially homogeneous cosmological system driven by this entropic source and enveloped by a time evolving apparent horizon, we formulate a modified version of the second law of thermodynamics. An explicit differential equation governing the internal entropy profile is found. Using a Hessian matrix analysis of the internal entropy we check the thermodynamic stability for a {\Lambda}CDM cosmology, a unified cosmic expanson and a non-singular ekpyrotic bounce. We find the mathematical condition for a second order phase transition during these evolutions from the divergence of specific heat at constant volume. The condition is purely kinematic and quadratic in nature, relating the deceleration parameter and the jerk parameter that chalks out an interesting curve on the parameter space. This condition is valid even without the entropic source term and may be a general property of any phase transition.