The observable universe could be a 1 + 3-surface (the "brane") embedded in a 1 + 3 + d-dimensional spacetime (the "bulk"), with Standard Model particles and fields trapped on the brane while gravity is free to access the bulk. At least one of the d extra spatial dimensions could be very large relative to the Planck scale, which lowers the fundamental gravity scale, possibly even down to the electroweak (∼ TeV) level. This revolutionary picture arises in the framework of recent developments in M theory. The 1 + 10-dimensional M theory encompasses the known 1 + 9-dimensional superstring theories, and is widely considered to be a promising potential route to quantum gravity. General relativity cannot describe gravity at high enough energies and must be replaced by a quantum gravity theory, picking up significant corrections as the fundamental energy scale is approached. At low energies, gravity is localized at the brane and general relativity is recovered, but at high energies gravity "leaks" into the bulk, behaving in a truly higher-dimensional way. This introduces significant changes to gravitational dynamics and perturbations, with interesting and potentially testable implications for high-energy astrophysics, black holes, and cosmology. Brane-world models offer a phenomenological way to test some of the novel predictions and corrections to general relativity that are implied by M theory. This review discusses the geometry, dynamics and perturbations of simple brane-world models for cosmology and astrophysics, mainly focusing on warped 5-dimensional brane-worlds based on the Randall-Sundrum models.

中文翻译：

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Brane-World Gravity。

可观察到的宇宙可以是嵌入1 + 3 + d维时空（“体”）中的1 + 3面（“叶片”），其中标准模型粒子和场被俘获在麸质上，而重力可以自由地访问批量。相对于普朗克尺度，d个额外空间维度中的至少一个可能非常大，这会降低基本重力尺度，甚至可能降至电弱（〜TeV）水平。这种革命性的画面是在M理论的最新发展框架中产生的。1 + 10维M理论涵盖了已知的1 + 9维超弦理论，被广泛认为是实现量子引力的有希望的潜在途径。广义相对论无法描述足够高能量下的引力，必须用量子引力理论代替，随着基本能源规模的临近，进行了重大的修正。在低能量时，重力位于米糠处，并且恢复了广义相对论，但是在高能量时，重力以真正的高维方式“泄漏”到主体中。这给引力动力学和扰动带来了重大变化，对高能天体物理学，黑洞和宇宙学产生了有趣的且可能是可检验的含义。Brane-world模型提供了一种现象学方法，可以测试M理论所暗示的一些相对于广义相对论的新颖预测和修正。这篇评论讨论了简单的宇宙学和天体物理学的布雷恩世界模型的几何，动力学和摄动，主要集中在基于兰德尔-森德鲁姆模型的扭曲的5维布雷恩世界。