论文标题
流体中的岛屿：岛屿在宇宙学上很常见
Islands in the Fluid: Islands are Common in Cosmology
论文作者
论文摘要
我们讨论了在宇宙学上的纠缠岛的可能性，并具有一般的完美液体，并有一个状态$ w $。我们发现，具有时间对称切片的平坦宇宙，其中哈勃参数消失总是在该切片上有岛屿。然后，我们考虑到具有一般完美液体的静物，远离了此类切片。在局部热平衡假设下，共同熵密度$ s_c $是恒定的。结果，一个岛屿的条件在归一化时期的能量密度（或哈勃参数）与温度之间成为不平等。后果是，几乎所有不是辐射的流体，即$ w \ neq 1/3 $都可以存在岛屿。我们还讨论了我们对空间曲率的宇宙结果的影响。最后，我们表明岛屿发生在简单的谐波宇宙模型中，该模型在背景层面没有经典的奇异性，与以前的所有岛屿仅在奇异性的太空时间发生的所有示例相比。
We discuss the possibility of entanglement islands in cosmological spacetimes with a general perfect fluid with an equation of state $w$. We find that flat universes with time-symmetric slices where the Hubble parameter vanishes always have islands on that slice. We then move away from such slices, considering still universes with a general perfect fluid. Under the local thermal equilibrium assumption, the comoving entropy density $s_c$ is constant. As a result, the conditions for an island become an inequality between the energy density (or Hubble parameter) and the temperature at some time of normalization. The consequences are that islands can exist for practically all fluids that are not radiation, i.e. $w\neq 1/3$. We also discuss the ramifications of our results for universes with spatial curvature. Finally, we show that islands occur in the Simple Harmonic Universe model which has no classical singularity at the background level, in contrast to all previous examples where islands occurred only in space-times with singularities.
