论文标题
在铁天空下：在宇宙开头的熵上
Under an Iron Sky: On the Entropy at the Start of the Universe
论文作者
论文摘要
奇怪的是，我们的宇宙出生在低矮的熵状态下，为电力星和生命提供了丰富的自由能。这种自由能的形式通常被认为是引力：宇宙几乎是完全光滑的，因此可以随着重力下的物质崩溃而产生能量来源。最近有人认为，低渗透能量的更重要的来源是核的：宇宙的扩展太快，无法保持核统计平衡（NSE），在前几分钟内有效地关闭了核合成，提供了剩余的氢作为恒星的燃料。在这里，我们填补了这种情况的天体物理细节，并寻求宇宙将从早期的核合成中出现的条件几乎是铁。这样一来，我们就确定了第二定律起源的故事中迄今被忽视的角色：Matter-Antimatter不对称。
Curiously, our Universe was born in a low entropy state, with abundant free energy to power stars and life. The form that this free energy takes is usually thought to be gravitational: the Universe is almost perfectly smooth, and so can produce sources of energy as matter collapses under gravity. It has recently been argued that a more important source of low-entropy energy is nuclear: the Universe expands too fast to remain in nuclear statistical equilibrium (NSE), effectively shutting off nucleosynthesis in the first few minutes, providing leftover hydrogen as fuel for stars. Here, we fill in the astrophysical details of this scenario, and seek the conditions under which a Universe will emerge from early nucleosynthesis as almost-purely iron. In so doing, we identify a hitherto-overlooked character in the story of the origin of the second law: matter-antimatter asymmetry.
