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arXiv 1912.04470gr-qc
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论热力学与广义相对论的联系

On the Connections between Thermodynamics and General Relativity

Jessica Santiago

摘要:

本文探讨了热力学与广义相对论之间的联系。我们回顾了由理查德·托尔曼首先提出的平衡态中引力诱导温度梯度的概念。我们探索这些托尔曼式的温度梯度,了解它们的物理起源,以及它们是否可以由其他力量产生。然后,我们概括了这个概念的流体通用四速度,这不一定是由Killing矢量,在一般静止的时空。然后,我们转向一个更基本的问题:我们还能为非基灵流定义热平衡吗?为了回答这个问题,我们回顾了相对论性非完美流体的两个主要理论:经典不可逆热力学和扩展不可逆热力学。我们还参观了有趣的概念Born刚性运动,显示了一些明确的例子,非Killing刚性流的Bianchi I型时空。这些结果是重要的,因为它们表明,Herglotz-Noether定理不能扩展到一般弯曲的时空。然后,我们连接Born刚性的概念与相对论流体的平衡条件所得到的结果,并表明,精确的热力学平衡只能实现沿Killing流。然而,我们引入了一些有趣的可能性,这些可能性允许非Killing流。接下来,我们进入黑洞热力学,特别是研究霍金辐射的trans-Planckian问题。我们构造了一个运动学模型,该模型由两个Vaidya时空沿薄壳匹配组成,并表明,只要霍金辐射发射距离视界只有几个普朗克长度(在适当的距离),trans-Plackian问题可以避免。

英文摘要:

In this thesis, the connections between thermodynamics and general relativity are explored. We review the concept of gravitationally induced temperature gradients in equilibrium states, first introduced by Richard Tolman. We explore these Tolman-like temperature gradients, understanding their physical origin and whether they can be generated by other forces or not. We then generalize this concept for fluids following generic four-velocities, which are not necessarily generated by Killing vectors, in general stationary space-times. We then move to a more fundamental question: can we still define thermal equilibrium for non-Killing flows? To answer this we review two of the main theories of relativistic non-perfect fluids: Classical Irreversible Thermodynamics and Extended Irreversible Thermodynamics. We also take a tour through the interesting concept of Born-rigid motion, showing some explicit examples of non-Killing rigid flows for Bianchi Type I space-times. These results are important since they show that the Herglotz--Noether theorem cannot be extended for general curved space-times. We then connect the Born-rigid concept with the results obtained by the relativistic fluid's equilibrium conditions and show that the exact thermodynamic equilibrium can only be achieved along a Killing flow. We do, however, introduce some interesting possibilities which are allowed for non-Killing flows. Following, we launch into black hole thermodynamics, specifically studying the trans-Planckian problem for Hawking radiation. We construct a kinematical model consisting of matching two Vaidya spacetimes along a thin shell and show that, as long as the Hawking radiation is emitted only a few Planck lengths (in proper distance) away from the horizon, the trans-Plackian problem can be avoided.

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