旋转和伪旋转
Rotation and pseudo-rotation
摘要：
应力-能量张量（爱因斯坦方程的源）的本征向量形成了描述相应时空的特权基础。当这些向量场中的一个或多个旋转时（在微分几何中很好地确定了这一性质），我们说时空执行了这种旋转。虽然旋转在其正确的意义上被理解为类时同余（向量场）的旋转，但如果类空同余的旋转对应于由刚才提到的本征向量构建的正则真基，则它不是一个不太客观的性质。在最后一种情况下，我们建议谈谈伪旋转。本文考虑了度规的性质、物质来源和时空对称性。
英文摘要：
Eigenvectors of stress-energy tensor (the source in Einstein's equations) form privileged bases in description of the corresponding space-times. When one or more of these vector fields are rotating (the property well determined in differential geometry), one says that the space-time executes this rotation. Though the rotation in its proper sense is understood as that of a timelike congruence (vector field), the rotation of a spacelike congruence is not a less objective property if it corresponds to a canonical proper basis built of the just mentioned eigenvectors. In this last case, we propose to speak on pseudo-rotation. Both properties of metric, its material sources, and space-time symmetries are considered in this paper.
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。
