arXiv 0811.41552008-11gr-qchep-thmath-phmath.MP

（2+1）维引力中的宇宙学测量、时间和可观测量

Cosmological measurements, time and observables in (2+1)-dimensional gravity

C. Meusburger

备注：: 38 pages, 11 eps figures, typos corrected, references updated
发表信息：: Class.Quant.Grav.26:055006,2009
DOI：: 10.1088/0264-9381/26/5/055006

摘要：

研究了在宇宙学常数为零的（2+1）引力场中具有紧致空间曲面的真空时空的测量值与物理观测值之间的关系。通过考虑一个观察者发出的光在稍后的时间返回给他，我们得到了几个可测量的量作为理论的物理相空间的函数的显式表达式：在光托盘的发射和其返回到观察者之间经过的本征时间，光必须发射以返回到观察者的方向之间的角度和光的相对频率，它们的发射和返回。这提供了一个框架，在其中可以解决有关时间，可观测和测量的概念问题。我们分析了这些测量的性质和它们的几何解释，并展示了它们如何允许观测者确定参数化（2+1）-引力的物理相空间的威尔逊圈观测值。我们讨论了时间在理论中的作用，并证明了观察者相对于时空几何的规范相当于一个规范固定过程，产生狄拉克观测。

英文摘要：

We investigate the relation between measurements and the physical observables for vacuum spacetimes with compact spatial surfaces in (2+1)-gravity with vanishing cosmological constant. By considering an observer who emits lightrays that return to him at a later time, we obtain explicit expressions for several measurable quantities as functions on the physical phase space of the theory: the eigentime elapsed between the emission of a lightray and its return to the observer, the angles between the directions into which the light has to be emitted to return to the observer and the relative frequencies of the lightrays at their emission and return. This provides a framework in which conceptual questions about time, observables and measurements can be addressed. We analyse the properties of these measurements and their geometrical interpretation and show how they allow an observer to determine the values of the Wilson loop observables that parametrise the physical phase space of (2+1)-gravity. We discuss the role of time in the theory and demonstrate that the specification of an observer with respect to the spacetime's geometry amounts to a gauge fixing procedure yielding Dirac observables.

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。

摘要：

英文摘要：

相关论文