利用拉格朗日量求解黑洞背景下自由光子的运动  

Solving the motion of free photons in black hole background via Lagrangian

作　　者：魏少文 付春娥 WEI Shao-wen;FU Chun-e(School of Physical Science and Technology,Lanzhou University,Lanzhou,Ganshu730000,China;School of Science,Xi'an Jiaotong University,Xi'an,Shaanxi 710049,China)

机构地区：[1]兰州大学物理科学与技术学院力学基础教研室,甘肃兰州730000 [2]西安交通大学物理学院应用物理系,陕西西安710049

出　　处：《大学物理》2022年第5期23-24,68,共3页College Physics

基　　金：国家自然科学基金(12075103),西安交通大学基本科研业务费(xzy012019061)资助。

摘　　要：利用拉格朗日量求解力学问题是一种很有用的方法.本文将借助于拉格朗日量求解黑洞时空背景下自由光子的运动,在求得光子的四速度之后,借助于机械能守恒定律,考察具有不同能量的光子在黑洞背景下所允许的运动范围.随后根据力学中运动学反问题,最终得到光子的运动轨迹.Solving mechanical problems with Lagrangian is a very useful method.In this paper,the motion of free photons in the background of a black hole is solved by means of Lagrangian.After obtaining the four velocities of photons,the allowable motion range of photons with different energies is studied by means of the law of conservation of mechanical energy.Then,according to the inverse problem of kinematics in mechanics,the trajectory of photons is finally obtained.

关 键 词：拉格朗日量 机械能守恒 黑洞 

分 类 号：O442[理学—电磁学]