光子、热力学与膨胀宇宙  

Photons, thermodynamics, and expanding universe

作　　者：李惕碚[1,2,3] 吴枚[1] 

机构地区：[1]中国科学院高能物理研究所粒子天体物理重点实验室,北京100049 [2]清华大学物理系,清华大学天体物理中心,北京100084 [3]中国科学院大学物理科学学院,北京101408

出　　处：《科学通报》2015年第34期3306-3312,共7页Chinese Science Bulletin

基　　金：国家自然科学基金(11033003)资助

摘　　要：基于宇宙学观测以及含宇宙常数的广义相对论场方程建立的标准宇宙模型,存在着违背物理学基本规律的疑难,提示我们需要仔细审视宇宙动力学的物理基础.例如,同实物退耦后的背景黑体辐射光子数目不再随宇宙膨胀而变化,但宇宙学红移效应导致辐射温度反比于宇宙尺度下降,则背景辐射总能量也反比于宇宙尺度而不断减少,违背了热力学第一定律,损失的宇宙背景辐射能量到哪里去了?又如,宇宙常数对应的暗能量密度不随时间变化,膨胀宇宙中物质不断被创生,总能量随宇宙膨胀趋于无穷.在宇宙学中坚持能量守恒,需要限制暗物质和暗能量的基本物理性质,其中作为零质量玻色子的光子扮演着重要角色.基于爱因斯坦场方程同时又不放弃能量守恒定律的宇宙学模型,给出了和标准模型完全不同因而可以被观测证实或证伪的演化图景:暗物质同暗能量平衡状态下的匀速膨胀才是宇宙的常态,而减速或加速膨胀只是宇宙介质相变导致的瞬态过程.近期开始出现的高精度宇宙学观测结果对标准模型提出了挑战,而有利于能量守恒宇宙模型的预期.正在进行和计划中的宇宙学观测将最终判定2类模型,并且推动基本物理的发展.The total number of blackbody photons of cosmic background radiation after decoupling from matter is independent of time,but the cosmic redshift effect lets the radiation tempreture decrease with the universe scale increasing,then the total energy of cosmic background radiation decreases as the universe expands,which is contrary to the first law of thermodynamics. The density of dark energy corresponding to the cosmological constant is independent of time,which means that matter is continuously created in an expanding universe,then the total energy of the universe will reach to infinity. The paradoxes in the standard model of cosmology indicate that the foundation of cosmic dynamics needs to be carefuly inspected. We propose an alternative model of cosmology with energy conservation giving an evolution picture of universe completely different with the standard model. In our model the state of equilibrium between matter and dark energy with a constant expansion rate is ordinary for universe,acceleration or deceleration is just temporary deviation from the equilibrium state by a phase transition with transformation between balanced matter and dark energy. It is expected that cosmological observations will judge the two kinds of cosmological model.

关 键 词：宇宙背景辐射 热力学 暗物质 暗能量 宇宙动力学 

分 类 号：P159[天文地球—天文学]