We demonstrate that the rapidity and robustness of slow contraction in homogenizing and flattening the universe found in simulations in which the initial conditions were restricted to non-perturbative variations described by a single Fourier mode along only a single spatial direction are in general enhanced if the initial variations are along two spatial directions, include multiple modes, and thereby have reduced symmetry. Particularly significant are shear effects that only become possible when variations are allowed along two or more spatial dimensions. Based on the numerical results, we conjecture that the counterintuitive enhancement occurs because more degrees of freedom are activated which drive spacetime away from an unstable Kasner fixed point and towards the stable Friedmann-Robertson-Walker fixed point.

我们证明了在模拟中发现的均匀化和扁平化宇宙的缓慢收缩的快速性和稳健性，在模拟中，初始条件仅限于由单个傅立叶模式描述的非微扰变化，仅沿单个空间方向通常会得到增强如果初始变化沿两个空间方向，则包括多个模式，从而降低了对称性。特别重要的是剪切效应，只有当允许沿两个或更多空间维度发生变化时，才会成为可能。基于数值结果，我们推测违反直觉的增强发生是因为更多的自由度被激活，驱动时空远离不稳定的卡斯纳不动点，朝向稳定的弗里德曼-罗伯逊-沃克不动点。