标题： 没有时间开端的广义相对论宇宙学 显示英文标题

标题： General relativistic cosmology with no beginning of time

摘要： 我们发现广义相对论可以自然地避免宇宙学奇点。目前有几种非奇点模型，它们要么假设了任意的物质内容，要么仅在解空间的一个测度为零的区域内是非奇点的，或者在高能情况下与广义相对论有显著偏离。在是否宇宙暴胀能够帮助解决初始奇点问题上经历了许多不确定性，如今普遍认为，无论是否有暴胀，广义相对论宇宙学本质上是奇点的。这种信念最近被特别考虑到暴胀的奇点定理所加强。在这里，我们详细推导出一个可行的暴胀宇宙学模型，尽管它1）仅使用经典广义相对论，2）仅假设最一般的暴胀物质内容，3）是一种混沌暴胀类型的理论，但它自然地避免了奇点。这种类型的暴胀目前最为广泛接受，因为它对初始条件的微调要求最少。还展示了如何通过放弃物质与几何之间通常的最小耦合简化，来违反零能量条件并绕过相关的奇点定理。 显示英文摘要

摘要： We find that general relativity can be naturally free of cosmological singularities. Several nonsingular models are currently available that either assume ad hoc matter contents, or are nonsingular only over a sector of solution space of zero measure, or depart drastically from general relativity at high energies. After much uncertainty over whether cosmological inflation could help solve the initial-singularity problem, the prevailing belief today is that general relativistic cosmology, with inflation or without, is endemically singular. This belief was reinforced by recent singularity theorems that take account specifically of inflation. Here, a viable inflationary cosmology is worked out that is naturally free of singularities despite the fact that 1) it uses only classical general relativity, 2) it assumes only the most generic inflationary matter contents, and 3) it is a theory of the chaotic-inflation type. That type of inflation is the most widely accepted today, as it demands the least fine-tuning of initial conditions. It is also shown how, by dropping the usual simplification of minimal coupling between matter and geometry, the null energy condition can be violated and the relevant singularity theorems circumvented.