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arXiv 0812.3744gr-qc
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签名变化事件:对量子引力的挑战?

Signature change events: A challenge for quantum gravity?

Angela White, Silke Weinfurtner, Matt Visser

摘要:

在欧几里得(泛函积分)量子引力或正则广义相对论的框架内,流形的签名是先验无约束的。此外,紧急时空计划的最新发展导致了物理上可行的签名变化事件的实施。这表明,现在是时候重新审视广义相对论中有时有争议的签名变化话题了。具体来说,我们将集中在行为的量子场受到流形包含不同的签名区域。我们强调,无论潜在的经典理论,有严重的问题与任何量子场论居住在一个签名变化的背景。(Such就像产生了无限数量的粒子,具有无限的能量密度。)从量子引力唯象的观点出发,讨论了有效洛伦兹对称性破缺标度的可能结果。为了更全面地理解暴露于有限区域的欧几里得签名(黎曼)几何的量子场的物理学,我们显示了它与量子势垒穿透问题的相似之处,以及宇宙学中遇到的超哈勃视界模式。最后,我们提出了一个问题,签名变化过渡是否可以完全理解和动态产生(修改)经典广义相对论,或者他们是否需要一个完整的量子引力理论的知识。

英文摘要:

Within the framework of either Euclidian (functional-integral) quantum gravity or canonical general relativity the signature of the manifold is a priori unconstrained. Furthermore, recent developments in the emergent spacetime programme have led to a physically feasible implementation of signature change events. This suggests that it is time to revisit the sometimes controversial topic of signature change in general relativity. Specifically, we shall focus on the behaviour of a quantum field subjected to a manifold containing regions of different signature. We emphasise that, regardless of the underlying classical theory, there are severe problems associated with any quantum field theory residing on a signature-changing background. (Such as the production of what is naively an infinite number of particles, with an infinite energy density.) From the viewpoint of quantum gravity phenomenology, we discuss possible consequences of an effective Lorentz symmetry breaking scale. To more fully understand the physics of quantum fields exposed to finite regions of Euclidean-signature (Riemannian) geometry, we show its similarities with the quantum barrier penetration problem, and the super-Hubble horizon modes encountered in cosmology. Finally we raise the question as to whether signature change transitions could be fully understood and dynamically generated within (modified) classical general relativity, or whether they require the knowledge of a full theory of quantum gravity.

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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