标题： 引力熵的上下界 显示英文标题

标题： Upper and Lower Bounds on Gravitational Entropy

摘要： 宇宙内部的熵有许多贡献，包括来自辐射和残留中微子的已知贡献。 引力熵更大且更微妙。 其中一个贡献提供了我们的下限，来自星系中心的超大质量黑洞。 其余部分更难确定。 我们建议一个上限，该上限比全息界限小多个数量级，但仍高于超大质量黑洞的熵。 我们提出，暗物质晕中的引力熵是目前宇宙熵的最大贡献者。 显示英文摘要

摘要： The entropy in the interior of the Universe has many contributions including well understood ones from radiation and relic neutrinos. The gravitational entropy is larger and more subtle. One contribution which provides our lower bound is from supermassive black holes at the centers of galaxies. The remainder is harder to pin down. We suggest an upper bound which is many orders of magnitude below the holographic bound yet above that of the supermassive black holes. We propose that gravitational entropy in dark matter halos is the largest contributor to the present entropy of the universe.