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arXiv 0709.1078gr-qc
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孤立系的Angular momentum

Angular momentum of isolated systems

Adam D. Helfer

摘要:

彭罗斯的twistorial的方法来定义角动量在零无穷大的发展,使角动量在不同的削减可以有意义的比较。这是通过证明与scri的不同切割相关联的扭量空间可以被识别为流形(但不是向量空间)来完成的。其结果是辐射时空中角动量的一个定义明确的、邦迪-梅茨纳-萨克斯不变量的概念;以前遇到的困难和含糊之处都与试图用特殊相对论术语来表达这一点有关,特别是与试图确定一个单一的闵可夫斯基起源空间有关。与特殊相对论情形不同,角动量不能用一个纯粹的j=1的量M_{ab}来表示,但也有更高的j贡献。应用标准的运动处方,这些较高的J贡献被证明是精确对应的剪切。这样看来,切变和角动量应该被看作是一个统一概念的不同方面。

英文摘要:

Penrose's twistorial approach to the definition of angular momentum at null infinity is developed so that angular momenta at different cuts can be meaningfully compared. This is done by showing that the twistor spaces associated with different cuts of scri can be identified as manifolds (but not as vector spaces). The result is a well-defined, Bondi-Metzner-Sachs-invariant notion of angular momentum in a radiating space-time; the difficulties and ambiguities previously encountered are attached to attempts to express this in special-relativistic terms, and in particular to attempts to identify a single Minkowski space of origins. Unlike the special-relativistic case, the angular momentum cannot be represented by a purely j=1 quantity M_{ab}, but has higher-j contributions as well. Applying standard kinematic prescriptions, these higher-j contributions are shown to correspond precisely to the shear. Thus it appears that shear and angular momentum should be regarded as different aspects of a single unified concept.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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