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上海交通大学自然科学研究院最新成果:简单热力学系统的温度上限

近期,上海交通大学自然科学研究院及物理与天文系戴德昌和美国纽约州立大学布法罗分校Dejan Stojkovic 共同在Journal of Cosmology and Astroparticle Physics发表了题为 Maximal temperature in a simple thermodynamical system的文章。

依据热力学第三定律绝对零度不可能达到,因此绝对零度是任何热力学系统的温度下限。虽然热力学提出温度有下限,热力学对温度上限并没有提出任何限制。 然而依据引力量子化的条件,时空在普朗克时间及普朗克长度下将不再连续。经典力学不再适用,因此温度这个经典概念也将不适用。这个推论延伸出普朗克温度为所有温度的上限,而必须藉由引力量子化才能描述这样的系统。热力学系统必须藉由作用力来达成热平衡,而高能粒子在高温状态极有可能形成黑洞。本文章因此想回答是否在达到普朗克温度前,热运动粒子便有足够的能量形成黑洞并停止提升系统温度的可能。本研究的结果显示答案是肯定的。确实存在比普朗克温度还低的温度上限。在达到该温度限制后,黑洞的形成率已经过高,所有的粒子全部转换成黑洞,温度因此无法再往上提升。

Temperature in a simple thermodynamical system is not limited from above. It is also widely believed that it does not make sense talking about temperatures higher than the Planck temperature in the absence of the full theory of quantum gravity. Here, we demonstrate that there exists a maximal achievable temperature in a system where particles obey the laws of quantum mechanics and classical gravity before we reach the realm of quantum gravity. Namely, if two particles with a given center of mass energy come at the distance shorter than the Schwarzschild diameter apart, according to classical gravity they will form a black hole. It is possible to calculate that a simple thermodynamical system will be dominated by black holes at a critical temperature which is about three times lower than the Planck temperature. That represents the maximal achievable temperature in a simple thermodynamical system.

参考文献: De-Chang Daia and Dejan Stojkovicb, “Maximal temperature in a simple thermodynamical system”