[PDF]ASTR 610 Theory of Galaxy Formation - Yale University
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More Riemannian Geometry. Equivalence Principles. General ... An inertial frame is a frame of reference that has a constant velocity with respect to the distant ...
An inertial frame is a frame of reference that has a constant velocity with respect to
the distant stars, i.e., it is moving in a straight line at a constant speed, or it is standing
still. It is a non-accelerating frame, in which the laws of physics take on their simplest
forms, because there are no fictitious forces.
A non-inertial frame is a frame of reference that is accelerating. In a non-inertial frame
the motion of objects is affected by fictitious forces (e.g, centrifugal & coriolis force).
An invariant is a property or quantity that remains unchanged under some transformation
of the frame of reference (i.e., charge of an electron, Planck’s constant, any scalar)
Covariance is the invariance of the physical laws or equations under some transformation
of the frame of reference.
the distant stars, i.e., it is moving in a straight line at a constant speed, or it is standing
still. It is a non-accelerating frame, in which the laws of physics take on their simplest
forms, because there are no fictitious forces.
A non-inertial frame is a frame of reference that is accelerating. In a non-inertial frame
the motion of objects is affected by fictitious forces (e.g, centrifugal & coriolis force).
An invariant is a property or quantity that remains unchanged under some transformation
of the frame of reference (i.e., charge of an electron, Planck’s constant, any scalar)
Covariance is the invariance of the physical laws or equations under some transformation
of the frame of reference.
引力探测器B证明爱因斯坦是对的
美探测器证实广义相对论两项关键预测。
（图片提供：Bob Kahn/引力探测器B/斯坦福大学）
本报讯 物理学家于5月4日宣布，美国宇航局（NASA）的一部耗资7.6亿美元的探测器终于成功证明了爱因斯坦的引力理论，或者说广义相对论，而这一构想已经提出了50年之久。引力探测器B完成的测量与广义相对论的两种效应的理论预测相一致——广义相对论认为，当质量使时空产生弯曲时便会产生引力。“爱因斯坦万岁！”加利福尼亚州帕洛阿尔托市斯坦福大学的物理学家Francis Everitt这样说道。Everitt于当天在NASA华盛顿总部召开的新闻发布会上报告了这一结果。
经过几十年的发展，引力探测器B从2004 年开始，在17个月的时间里从南极到北极环绕地球运行，同时利用陀螺仪测量广义相对论的两个观点。其中一个便是测地线效应，是指引力场的时空曲率对处于其中的具有自旋角动量的测试质量的运动状态所产生的影响，这种影响造成了测试质量的自旋角动量在引力场内沿测地线的进动。结果显示，地球周长略短于地球半径的2π倍。
探测器还证实了参考系拖拽效应，这是指一种处于转动状态的质量会对其周围的时空产生拖拽的现象。Everitt解释说，这就像旋转的地球被沉浸于蜂蜜中一样。他说：“当地球旋转，它将拖拽周围的蜂蜜。同样，地球也应对时空产生拖拽效应。”
据介绍，引力探测器B的主要装备是4个超高精度的回转仪。当引力探测器B在距离地球约640公里的极地轨道上开始运转时，4个回转仪自转轴同时对准遥远恒星——IMPegasi。如果地球引力不影响时间和空间，那么回转仪自转轴将一直指向初始方向。实际观测结果是，受地球引力拖拽，回转仪自转轴方向发生了可测量的细微偏移拽，从而证实了爱因斯坦的理论。
据介绍，引力探测器B是NASA在2004年4月20日发射的一颗科学探测卫星。这个任务的计划是测量地球周围的时空曲率，以及相关的动量张量（描述物质的分布及运动的张量），从而对爱因斯坦的广义相对论的正确性和精确性进行检验。卫星的飞行持续到2005年，任务从2008年5月进入到了数据分析阶段。引力探测器B的研发历史可追溯到20世纪60年代，是NASA历史上研发时间最长的计划。
Everitt认为：“引力探测器B证实了爱因斯坦的两项最深奥的预测，对天体物理学研究具有深远意义。”
这项研究成果已发表在《物理评论快报》杂志网络版上。（赵路）
《科学时报》 (2011-05-06 A4 国际)
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www.astro.yale.edu/.../astro610_lecture3.pd...
More Riemannian Geometry. Equivalence Principles. General ... An inertial frame is a frame of reference that has a constant velocity with respect to the distant ...
Yale University Observatory
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General Relativity and Cosmology - Page 70 - Google Books Result
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