恒星宇宙模型——另一个FLRW补丁
The Star Universe Model -- Another FLRW Patch
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中文总结 AI 辅助
本文提出恒星宇宙模型替代黑洞宇宙模型，仅用完美流体解释宇宙，给出密度上限并计算暴胀，以递减有效宇宙常数解释晚期加速膨胀。
中文摘要 AI 辅助
黑洞宇宙模型已在文献中得到发展。该模型假设宇宙的全部质量在经历球形坍缩后仍保持在黑洞的史瓦西半径之内。我们给出了一个图形化证明，并表明在经典理论范畴内，如果时空在演化坍缩/反弹过程中始终保持正则，则这是不可能的。还讨论了其他缺点。作为替代，我们提出了恒星宇宙模型。在该模型中，除了完美流体本身之外，不考虑其他成分（如暴胀场和暗能量），并且自然地引入了正空间曲率以及粒子产生率函数。我们讨论了新旧静态解，证明了引力质量为$M_{\text{g}}$的半封闭宇宙的密度上限为$3c^6/(32 \pi G^3 M_{\text{g}}^2)$，并阐述了宇宙的诞生，在恒星宇宙模型内计算了其暴胀速率。当演化解接近广义爱因斯坦静态宇宙（具有均匀能量密度和负压力）时，暴胀状态会平滑优雅地退出，膨胀在宇宙学时间上变为线性，密度和（负）总压力与尺度因子倒数的平方成正比。如果发生（再）坍缩，密度和（正）压力也会出现类似行为。分析结果得到一个随时间变化且递减的有效宇宙学常数$8\pi G\rho(\tau)/c^2$，在晚期几乎保持不变，这解释了以三倍哈勃参数的粒子产生速率驱动的晚期加速膨胀。
英文摘要
The Black Hole Universe model has advanced in the literature. It assumes that the whole mass of the Universe remains inside the Schwarzschild radius of a black hole after being subject to a spherical collapse. We present a graphical proof and show that within the realm of classical theory this is not possible if spacetime remains regular at all times during the evolving collapse/bounce. Other drawbacks are discussed. As an alternative, we propose the Star Universe Model. In this model no other ingredients (such as inflaton field and dark energy) other than the perfect fluid itself are considered, and a positive spatial curvature is naturally introduced along with a particle production rate function. We discuss new-old static solutions, show that the density of a semi-closed Universe of gravitational mass $M_{\text{g}}$ is bounded from above by $3c^6/(32 πG^3 M_{\text{g}}^2)$, and elaborate on the birth of the Universe and calculate its inflation rate within the Star Universe Model. A smooth graceful exit from inflationary state occurs as the evolutionary solution approaches the generalized Einstein static Universe (with uniform energy density and negative pressure) and the expansion becomes linear in cosmological time with density and (negative) total pressure proportional to the square of the inverse of the scale factor. A similar behavior for density and (positive) pressure will occur if (re)collapse takes place. The analysis results in a time variable and decreasing effective cosmological constant $8πGρ(τ)/c^2$, which remains almost constant at late times, that justifies the late accelerated expansion with a rate of particle production three times the Hubble parameter.
发表机构
- Başkent University（巴什特大学）
机构由 AI 辅助整理，请以论文原文为准。
