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arXiv 2108.02693gr-qcmath-phmath.DGmath.MGmath.MP
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洛伦兹长度空间上的时间函数

Time functions on Lorentzian length spaces

Annegret Burtscher, Leonardo García-Heveling

AI总结:

本文在 Lorentzian(预)长度空间框架下建立时间函数的经典存在性理论,用 $K$-因果性、因果连续性及 Cauchy 时间函数刻画相关性质,证明无需流形结构。

摘要:

在广义相对论中,时间函数是至关重要的对象,其存在性和性质与时空的因果结构以及 Einstein 方程的初值表述密切相关。在本工作中,我们在 Lorentzian(预)长度空间(包括因果平凡的连续时空、闭锥场乃至更奇异的空间)的框架下,建立了关于时间函数的所有基本经典存在性结果。更具体地说,我们通过 $K$-因果性刻画了时间函数的存在性,证明了 Geroch 体积函数的一种修正概念是时间函数当且仅当该空间因果连续,最后,通过 Cauchy 时间函数和 Cauchy 集的存在性刻画了整体双曲性。因此,我们的结果不可避免地表明,获得合适的时间函数并不需要流形结构。

英文摘要:

In general relativity, time functions are crucial objects whose existence and properties are intimately tied to the causal structure of a spacetime and also to the initial value formulation of the Einstein equations. In this work we establish all fundamental classical existence results on time functions in the setting of Lorentzian (pre-)length spaces (including causally plain continuous spacetimes, closed cone fields and even more singular spaces). More precisely, we characterize the existence of time functions by $K$-causality, show that a modified notion of Geroch's volume functions are time functions if and only if the space is causally continuous, and lastly, characterize global hyperbolicity by the existence of Cauchy time functions, and Cauchy sets. Our results thus inevitably show that no manifold structure is needed in order to obtain suitable time functions.

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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