论文标题
重力熵以及平坦，同质性和各向同性难题
Gravitational entropy and the flatness, homogeneity and isotropy puzzles
论文作者
论文摘要
我们建议对观察到的大规模平坦，均匀性和宇宙各向同性的新解释。基本成分是基本和众所周知的，即爱因斯坦的重力理论和霍金的计算重力熵方法。我们最近为“大爆炸”类型的奇异性主导的边界条件提供了新的扭曲，以保形物质为主，执行$ cpt $对称性和分析性。在这里，我们表明，除了允许我们描述大爆炸外，这些边界条件还允许新的引力激体散发，使我们能够计算宇宙学的重力熵，包括辐射，暗能量和任何一个符号的空间曲率。我们找到了这些宇宙的引力熵，$ s_g \ sims_λ^{1/4} s_r $，其中$s_λ$是著名的de de Sitter熵，$ s_r $是辐射的总熵。在$ s_g $超过$s_λ$的范围内，最可能的宇宙是平坦的。通过分析有关我们新激体顿的扰动，我们认为它在大尺度上也是均匀的和各向同性的。
We suggest a new explanation for the observed large scale flatness, homogeneity and isotropy of the universe. The basic ingredients are elementary and well-known, namely Einstein's theory of gravity and Hawking's method of computing gravitational entropy. The new twist is provided by the boundary conditions we recently proposed for "big bang" type singularities dominated by conformal matter, enforcing $CPT$ symmetry and analyticity. Here, we show that, besides allowing us to describe the big bang, these boundary conditions allow new gravitational instantons, enabling us to calculate the gravitational entropy of cosmologies which include radiation, dark energy and space curvature of either sign. We find the gravitational entropy of these universes, $S_g \sim S_Λ^{1/ 4} S_r$, where $S_Λ$ is the famous de Sitter entropy and $S_r$ is the total entropy in radiation. To the extent that $S_g$ exceeds $S_Λ$, the most probable universe is flat. By analysing the perturbations about our new instantons, we argue it is also homogeneous and isotropic on large scales.
