论文标题
一般相对论和触发性的切线空间对称性
Tangent space symmetries in general relativity and teleparallelism
论文作者
论文摘要
本文介绍了伪 - 利曼歧管上坐标的变化如何在其切线空间上诱导均匀的线性变换。我们看到,在给定的切线空间中的伪正常框架是一组Riemann正常坐标的基础。一般线性转换的洛伦兹亚组保留了这种伪正常。我们从非线性实现的方法中借用技术来分析这种群体 - 组结构。 “平行地图”用于将不同点处的切线空间联系起来。跨多个有限区域的“平行性”可以由它们建立。这些用于定义Weitzenböck连接和Levi-Civita连接。 这提供了远程平行性重力的新表述,其中四局场被视为字段值的组元素,将坐标基依据与定义并行性用于定义平行性的框架基础相关。这种公式将自由度的度量度与与平行性选择相关的自由度分开。组元素可以通过矩阵乘法与框架的洛伦兹变换或其他Jacobian矩阵结合使用。我们展示了这如何促进对惯性力量和局部洛伦兹转变的新理解。 该分析还应用于坐标的翻译。如果它们在整个时空持续不变,这对切线空间底座没有影响。如果翻译参数成为字段,它们会诱导坐标基础的一般线性变换。但是,四方组件只能以平坦时空的翻译来表示。
This paper looks at how changes of coordinates on a pseudo-Riemannian manifold induce homogeneous linear transformations on its tangent spaces. We see that a pseudo-orthonormal frame in a given tangent space is the basis for a set of Riemann normal coordinates. A Lorentz subgroup of the general linear transformations preserves this pseudo-orthonormality. We borrow techniques from the methodology of non-linear realizations to analyze this group-subgroup structure. `Parallel maps' are used to relate tangent space at different points. `Parallelisms' across a finite region of the manifold may be built up from them. These are used to define Weitzenböck connections and Levi-Civita connections. This provides a new formulation of teleparallel gravity, in which the tetrad field is viewed as a field-valued group element relating the coordinate basis to the frame basis used in defining a parallelism. This formulation separates the metric degrees of freedom from those associated with the choice of parallelism. The group element can be combined by matrix multiplication with Lorentz transformations of frame or with other Jacobian matrices. We show how this facilitates a new understanding of inertial forces and local Lorentz transformations. The analysis is also applied to translations of the coordinates. If they are constant across spacetime, this has no effect on the tangent space bases. If the translation parameters become fields, they induce general linear transformations of the coordinate basis; however, the tetrad components can only be expressed in terms of translations on a flat spacetime.