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arXiv 1507.04683gr-qcastro-ph.CO
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宇宙学黑洞与时间方向

Cosmological black holes and the direction of time

Gustavo E. Romero, Daniela Pérez, Federico G. Lopez Armengol

备注：
13 pages, 2 figures in Foundations of Science (2017)
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摘要：

宏观不可逆过程产生于可逆性质的基本物理定律。局部不可逆性的来源似乎不是定律本身，而是代表定律的方程的初始和边界条件。在这项工作中，我们提出，屏蔽电流的黑洞事件视界确定，本地，一个首选的方向的电磁能通量。研究了在不同的宇宙学模型下，由于宇宙膨胀和宇宙微波背景辐射吸积引起的黑洞事件视界的增长。我们提出了广义McVittie同动度规，并积分了宇宙微波背景辐射在超大质量黑洞上随宇宙时间的吸积速率.我们发现，对于平坦的，开放的，和封闭的弗里德曼宇宙学模型，黑洞事件视界的总面积相对于径向共同运动的类空超曲面的面积的比率总是增加。由于宇宙辐射的吸积为黑洞吸积的总物质设定了一个绝对下限，这意味着因果关系的过去和未来对于任何时空事件都不是镜像对称的。这种不对称性导致了全球未来方向的净坡印廷通量;后者反过来又与不断增加的热力学熵有关。因此，我们揭示了四个不同的“时间箭头”之间的联系：宇宙学，电磁，引力和热力学。

英文摘要：

Macroscopic irreversible processes emerge from fundamental physical laws of reversible character. The source of the local irreversibility seems to be not in the laws themselves but in the initial and boundary conditions of the equations that represent the laws. In this work we propose that the screening of currents by black hole event horizons determines, locally, a preferred direction for the flux of electromagnetic energy. We study the growth of black hole event horizons due to the cosmological expansion and accretion of cosmic microwave background radiation, for different cosmological models. We propose generalized McVittie co-moving metrics and integrate the rate of accretion of cosmic microwave background radiation onto a supermassive black hole over cosmic time. We find that for flat, open, and closed Friedmann cosmological models, the ratio of the total area of the black hole event horizons with respect to the area of a radial co-moving space-like hypersurface always increases. Since accretion of cosmic radiation sets an absolute lower limit to the total matter accreted by black holes, this implies that the causal past and future are not mirror symmetric for any spacetime event. The asymmetry causes a net Poynting flux in the global future direction; the latter is in turn related to the ever increasing thermodynamic entropy. Thus, we expose a connection between four different "time arrows": cosmological, electromagnetic, gravitational, and thermodynamic.

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